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Natural Mortality ot the Colorado potato beetle,

Leptlnotarsa decemllneata (Say)

by

Eleanor Groden

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILCBOPHY

Department of Entomology

1989

4714

I W
\_

4-

ABSTRACT

NATURAL MORTALITY OF THE COLORADO POTATO BEETLE,
LEPTINOTARSA DECEMLINEATA (SAY)

By

Eleanor Groden

This study was designed to explore the potential for developing endemic biological
controls for the Colorado potato beetle (CPB). A comparative study of the natural
mortality of the CPB was conducted over three years in both early and late potato
plantings in RI. and Mich., including regions with high and low population pressures.
Large larval and pupal mortality were most highly correlated with total mortality over
all plantings and research sites. Parasitism by the tachinid, Myiopharius doryphorae,
was correlated with pupal survival, but was inverse density dependent. In early planted
potatoes, egg mortality was most highly correlated with total survival. The incidence of
the coccinellid predator, Coleomegi/Ia macu/ata, was correlated with CPB egg and small
larval mortality in R.I., but not in Mich. The densities of the carabid predator, Lebia
grandis, were correlated with the densities of preyed CPB eggs in 1987 in both RI. and
Mich.

L. grandis was found to be primarily nocturnal, and a method of trapping was
developed for daytime sampling. Adult L. grandis densities were synchronized with CPB
egg and larval population in both RJ. and Mich. The release of tethered CPB prepupae
allowed for the sampling of the ectoparasitic larvae of L. grandis, and parasitism of CPB
pupae in Mich. exceeded 50% at peak pupal densities. Laboratory development studies
and field sampling indicated that this predator completes one generation per year in both

regions. L. grandis rate of prey consumption was greater than any CPB predator studied

to date.

Eleanor Groden

C. maculafa adult densities were synchronized with first generation CPB prey in
Mich., and first and second generation in R.I. The presence of alternate prey decreased
their consumption of CPB prey. C. macu/afa densities were higher in alfalfa and sweet
corn, than in potatoes.

CPB adult and larval infection by B. bassiana was lower in Mich. than R.I. Mich.
soils were more fungistatic than RJ. soils, and fungistasis was correlated with soil pH.
8. bassiana L050 levels determined for inoculated pupae incubated in the different soils

increased with increased soil fungistasis.

To my father, Harold Michael Groden. M.D.,
whose dedication, values, and humor
will always be with me.

and

To women in science.
may they go forth and multiply.

ii

ACKNOWLEDGMENTS

Many people have assisted me throughout this study, and contributed to my
education in science and entomology. Foremost, I would like to thank Dr. Dean Haynes,
my major professor, and Dr. Richard Casagrande. My many conversations with Dean
have helped shape my philosophies of science and entomology, and been the catalyst for
many of the ideas generated in my present and future research studies. And Dick, I would
like to thank for his assistance, encouragement, support, and clarity. It has been an
enjoyable asset working with Dick for the past many years, and I am grateful for his
contribution to my education, and his persistence in making things easier than I usually
cons"ued.

I would also like to thank the other members of my guidance committee: Dr.
Stuart Gage, for his friendship and much assistance in many areas during Dean's
absence; Drs. Ed Grafius and Dave Smitley for their advise and guidance, and Dr. John
Lockwood, for his patience and expert assistance as I jumped into a new discipline. And
to all my committee members I am grateful for the time spent reviewing this
manuscript. I am grateful to several members of the Entomology faculty and staff who
have contributed to my education and helped me out along the way. In particular I would
like to thank Dr. Fred Stehr and Ken Dimoff. To my fellow graduate students: Nancy
Campbell, Jan Ryan, Debbie Miller, Dave Cappaert, and Emily Olds, i would like to
extend my thanks for the conversations, humor and friendships that were a constant
source of encouragement.

I would also like to thank Dave Cappaert for his assistance in collecting data and
managing the early phase of this project in Michigan. And I am indebted to Heather
Faubert for managing much of the data collection in Rhode Island, her observations and
discussions about the research, her willingness to sit up all night with me in potato

fields, and her friendship.

iii

Most of all I would like to thank my colleague and best friend Dr. Frank
Drummond. For the many conversations about this project, entomology, science, life...,
for the assistance with planting, midnight predator counts, and countless other things,
and for the constant support and encouragement, I am truly grateful.

And a thanks to Nate and Brie for putting up with all this.

iv

TABLE OF CONTENTS

LIST OF TABLES
LIST OF FIGURES
INTRODUCTION
LITERATURE REVIEW
CPB LIFE HISTORY
POPULATION DYNAMICS OF CPB
ENDEMlC NATURAL ENEMIES
MANUSCRIPT 1. Stage-specific survival of the Colorado
potato beetle, Leptlnofarsa decemlfneata (Say)
(Coleoptera: Chrysomelldae) In early and late planted
potatoes In Rhode Island and Michigan
ABSTRACT
INTRODUCTION
MATERIAL AND METHODS
Study Sites
CPB and Natural Enemy Sampling
Estimating Total Seasonal Density and Stage-specific Survival
RESULTS AND DISCUSSION
CPB Colonization and Egg Recruitment
Total Seasonal Density and Stage-Specific Survival
Analysis of Within Generation Survival

UTERATURE CITED

viii

xi

27
29
3O
30
31
34
40
40
49
56

81

MANUSCRIPT 2. The biology and seasonal dynamics of
Lebfa grandis Hentz (Coleoptera: Carabldae), predator
and parasitold of the Colorado potato beetle,
Lepffnatarsa decemlineafa (Say) (Coleoptera:

Ch rysomelidae)

ABSTRACT 85
INTRODUCTION 86
MATERIAL AND METHODS 86
RESULTS 97
DISCUSSION 1 1 5
UTERATURE CTTED 1 2 O

MANUSCRIPT 3. Predation of the Colorado potato beetle
(Coleoptera: Chrysomelidae) by Coleomegllla maculafa
DeGeer (Coleoptera: Cocclnellldae), and Its incidence in

potatoes and surrounding crops

ABSTRACT 1 2 2
INTRODUCTION 1 2 3
MATERIALS AND METHODS 1 2 4
RESULTS 1 2 7
DISCUSSION 1 3 9
UTERATURE CITED 1 4 5

MANUSCRIPT 4. Effects of soil fungistasis on Beauverfa
bassiana (Bats) Vuill. and its‘relatlonship to disease
incidence in the Colorado potato beetle, Leptlnotarsa
decemlfneata (Say) in Michigan and Rhode Island soils
ABSTRACT 148
INTRODUCTION 149

vi

MATERIALS AND METHODS
RESULTS
DISCUSSION
UTERATURE CITED
SUMMARY AND CONCLUSIONS
APPENDICES
Appendix A. Modeling CPB oviposition
Appendix B. CPB oviposition on weeds
Appendix C. Densities of CPB lifestages and predators at
research sites in Rhode island and Michigan, 1985-1987

BIBLIOGRAPHY

vii

149
155
168
173
175

180

193

188
211

LIST OF TABLES

LITERATURE REVIEW

Table 1.

Table 2.

Table 3.

Table 4.

Table 5.

Natural enemies of the Colorado potato beetle endemic
to North America reported by Riley and Bethune,
1868-1876 .

Known North American hosts of Beauveria bassiana from
reports of natural incidence.

Known prey species of Peri/[us bioculatus.

Known prey species of Podisus maculivenlris (From
McPherson 1982).

Known prey species and food of Co/eomegilla maculafa.

MANUSCRIPT 1.

Table 1.

Table 2.

Table 3.

Table 4.

Table 5.

Table 6.

Table 7.

Accumulation of degree-days (base 10°C) from May 1,

at research sites in Rhode Island and Michigan, 1986-1987.

Results of ANOVA's for CPB egg mass size observed in Rhode
Island and Michigan potato research plantings in 1985 and
1986, and values of mean eggs/mass used for calculating egg
densities from observed egg mass densities.

Composition of CPB predator complexes in potato
research plots in Rhode Island and Michigan, 1985-1986.

Total seasonal production of CPB Iifestages in potato
research plots in Rhode Island and Michigan in 1985-1987.

Stage-specific survival of CPB in potato research plots
in Rhode Island and Michigan in 1985-1987.

Statistics from linear regression analysis testing for density
dependence in survival of immature stages of the CPB.

Parasitism of CPB pupae by Myiopharius dorphorae in

potato research plots in Rhode Island and Michigan in
1985-1 987.

viii

16
23

41

47

50

54

55

59

61

LIST OF TABLES (continued)

Table 8.

Beauveria bassiana infection of CPB adults and larvae in
potato research plots in Rhode Island and Michigan,
1 985-1 9 87 .

Table 9 Predation of CPB egg masses by haustellate and mandibulate

predators in potato research plantings in 1987.

MANUSCRIPT 2.

Table 1.
Table 2.

Table 3.

Table 4.

Lebia grandis consumption of immature stages of the CPB.

CPB egg and Lebia grandis densities in early potato plantings
in Rhode Island and Michigan, 1985-1987.

CPB egg and Lebia grandis densities in late potato plantings
in Rhode Island and Michigan, 1985-1987.

Consumption of CPB by endemic predators.

MANUSCRIPT 3.

Table 1.

Table 2.

Consumption of immature stages of the CPB by Co/eomegilla
maculata DeGeer adults.

Predicted ColeomegiI/a maculala physiological events at
research sites in Rhode Island and Michigan in 1986 and
1987, based on temperatures and degree-day models
developed by Wright and Laing (1978), Obrycki and Tauber
(1978), and Mack and Smilowitz (1982).

MANUSCRIPT 4.

Table 1.

Table 2.

Table 3.

Table 4.

Table 5.

Characteristics of soils used in Beauveria bassiana
fungistasis and dose-mortality assays.

Germination and log-probit regression results from
Beauveria bassiana fungistasis assay conducted for soils
collected in 1986 and 1987 from potato fields in Rhode
Island and Michigan.

Germination of Beauveria bassiana conidia in Rhode Island
and Michigan soils with 312.5 pg glucose per g of soil, 1987.

Mortality of CPB pupae inoculated with Beauveria bassiana
and incubated in different soils from Rhode island and Michigan,
1987.

Sporulation of Beauveria bassiana on CPB pupae inoculated

with different concentrations of conidia averaged over all
soils and replications (N = 10 individuals per replication).

ix

62

7O

98

107

108

117

128

141

156

161

163

165

166

LIST OF TABLES (continued)

Table 6. Sporulation of Beauveria bassiana on inoculated CPB pupae
in Rhode Island and Michigan soils averaged over all dosages
and replications (N - 10 individuals per replication).

APPENDIX A

Table A1. Predicted and observed egg recruitment in Rhode Island and
Michigan potato research plantings, 1985-1986.

APPENDIX B

Table B1. Comparison of CPB egg densities and the proportion of eggs
preyed upon on potato plants and weeds in potatoes at KBS
research plots, 1987.

APPENDIX C

Table C1. CPB densities at potato research sites in Rhode Island and
Michigan, 1985-1987.

Table CZ. Densities of CPB predators in potato research sites in Rhode
Island and Michigan, 1985-1987.

167

184

190

193

202

LIST OF FIGURES

MANUSCRIPT 1.

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Figure 11.

Densities of adult CPB in potato research plots at the
in Rhode Island, 1985-1987.

Densities of adult CPB in potato research plots at the
K88 site in Michigan, 1985-1987.

Densities of adult CPB in potato research plots at the
Montcalm site in Michigan, 1985-1987.

Daily oviposition of CPB eggs in potato research
plots in Rhode Island and Michigan, 1985 and 1986.

Error in sampling first instar CPB (incidence = mean
per plant x dd).

Graphical key-factor analysis of individual components
of CPB within-generation survival model.

The density of emerging CPB adults per plant in relation
to the number of Myiopharius doryphorae parasitized
pupae per plant.

The relationship between the incidence of large CPB larvae
(mean per plant x dd) and the proportion parasitized by
Myiopharius doryphorae.

The relationship between parasitism by Myiopharius
doryphorae and the occurrence of large CPB larvae in late
plantings of potato in Rhode Island and Michigan.

The relationship between parasitism by Myiopharius
doryphorae and the occurrence of large CPB larvae in early
plantings of potato in Rhode Island and Michigan.

The relationship between weekly estimates of Lebia grandis
densities and egg predation by mandibulate predators
(weighed by the density of total available prey) in early
planted potatoes at the KBS, Michigan and Rhode Island
research sites in 1987.

xi

43

44

45

46

53

58

63

64

66

66

73

LIST OF FIGURES (continued)

Figure 12.

Figure 13.

Figure 14.

Figure 15.

The relationship between Coleomegilla maculala incidence
(mean per plant x dd) and survival of CPB eggs and small
larvae in potato research plantings in Rhode Island,
1985-1987.

The relationship between the incidence (mean per plant
x dd) of Coleomegilla maculata and its CPB prey (eggs
and small larvae) in potato plantings in Rhode Island and
Michigan,1985-1987.

The relationship between the incidence (mean per plant

x dd) of pentatomid predators and total CPB prey (eggs,
small and large larvae) in a.) all potato plantings, 1985
-1987, and b.) in Michigan potato plantings,1985-1987.

Peril/us bioculatus and their CPB prey (egg masses +
total larvae) densities in early planted potatoes at the
K88 site in Michigan, 1986 and 1987.

MANUSCRIPT 2.

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Burlap trap used for sampling Lebia grandis

a.) Tethered CPB prepupa, b.) Tethered prepupa burrowing
into the soil, 0.) Parasitized CPB prepupa with adjacent
Lebia grandis.

CPB survival in field cages with Lebia grandis released on
August 15.

Lebia grandis consumption of CPB cohorts as a function of
prey density.

a.) Results of substituting different thresholds for Lebia
grandis egg development data, b.) Lebia grandis egg
development as a function of temperature.

a.) Results of substituting different thresholds for Lebia
grandis larval and pupal development data, b.) Lebia grandis
larval and pupal development as a function of temperature.
Seasonal variation in Lebia grandis consumption of CPB eggs.
Comparison of sampling methods for Lebia grandis adults.

a.) Densities of CPB stages in Michigan potato plots in 1987,
b.) Densities of Lebia grandis adults in Michigan potato plots
in 1987 (from midnight observations).

a.) Densities of CPB stages in Rhode Island potato plots in

1987, b.) Trap catches (mean per trap per day) of Lebia
grandis in Rhode Island potato plots in 1987.

xii

75

76

77

79

93

96

100

101

102

103

105

109

110

112

LIST OF FIGURES (continued)

Figure 11.

Figure 12.

Parasitism rate of tethered CPB prepupae and density of
CPB prepupae in Michigan plot in 1986.

Parasitism of tethered CPB prepupae and density of CPB
prepupae in Michigan plot in 1987.

MANUSCRIPT 3.

Figure 1.

Figure 2.

Figure 3

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Coleomegilla maculata adults daily consumption of CPB eggs
as a function of temperature.

Coleomegilla maculala adult consumption of CPB first instar
larvae in the presence of aphids (vertical bars are 95%
confidence intervals).

Predation on cohorts of CPB eggs by Coleomegilla maculafa
adults in field cages.

Daily consumption rate of Coleomegilla maculala adults as a
function of prey (CPB egg masses plus small larvae) density
in field cages.

Densities of Coleomegilla macu/ata adults and CPB prey per
plant in early and late planted potatoes in Rhode Island,
1 9 8 5 - 1 9 8 6 .

Densities of Coleomegilla maculafa adults and CPB prey per
plant in early and late planted potatoes at the K88 site in
Michigan, 1985-1986.

Densities of Coleomegilla maculafa adults and CPB prey per
plant in early and late planted potatoes at the Montcalm site
in Michigan, 1985-1986.

Densities of Coleomegilla maculata adults in potatoes and
surrounding crops at the K88 site in Michigan, 1986.

Densities of Coleomegilla maculafa adults in potatoes and
surrounding crops at the KBS site in Michigan, 1987.

MANUSCRIPT 4.

Figure 1.

Figure 2.

Figure 3.

Moisture characteristic curves for soils used in fungistasis
assays and Beauveria bassiana dose-mortality study.

Log-probit regressions of germination of Beauveria bassiana
in Rhode Island and Michigan soils in 1986 and 1987 as a
function of added glucose-peptone (pg glucose/g soil)

Relationship between fungistasis (expressed as glucose

concentration required for 50% germination of Beauveria
bassiana conidia) and soil pH.

xiii

113

114

130

131

133

134

136

137

138

140

159

160

164

LIST OF FIGURES (continued)

Figure 4. Relationship between fungistasis (expressed as glucose
concentration required for 50% germination of Beauveria
bassiana conidia) and estimated L050 values (conidial

concentrations/pupa necessary to kill 50% of the population).

APPENDIX A
Figure A1. Diagram of Stella® model of CPB oviposition.

Figure A2. CPB daily oviposition rate as a function of degree-day
accumulations (data from Grison 1950).

APPENDIX B

Figure 81. The proportion of CPB eggs oviposited on weeds in relation
to weed density.

xiv

169

182

183

191

INTRODUCTION

The Colorado potato beetle, Leplinofarsa decemlineafa (Say), (hereafter referred
to as CPB) is a pest of potatoes, Solanum tuberosum (L.) in the United States, Canada,
continental Europe, and the Soviet Union. The CPB appears to be native to Mexico, the
geographic origin of the genus Leplinotarsa (Tower 1906), where its primary host
plants are Solanum angustifolium Mill. and Solanum rostratum DunaI (Hsiao 1985).
The CPB was first collected on S. rostrafum (Buffalo bur) in 1811 in western Iowa and
appears to have adapted to potato ca. 40 years after the introduction of the crop to its
native range in 1820 (Casagrande 1985). The beetle rapidly spread eastward on its
new host plant, and has since become the most important insect pest of potatoes
throughout most of the potato producing areas in the world (Hsiao 1981).

CPB pest management has been dominated by chemical controls since the
introduction of Paris green in the mid 1800's (Gauthier et al. 1981, Casagrande 1987).
After 125 years of exclusive reliance on a sequence of insecticides, many regional CPB
populations have developed resistance to every available compound, and the effective life
of newly Introduced compounds has declined (Forgash 1981, 1985). The CPB has indeed
demonstrated itself to be an incredibly adaptable insect. overcoming the resistance of
wild potato plants within three generations (Groden and Casagrande 1986). It is evident
that the ”silver-bullet” approach will not provide a long-term solution to the potato
beetle problem, and future pest management programs for this insect must rely on the
Integration of cultural and biological controls.

Cultural control measures were recommended for management of the CPB in the
1800's, but were abandoned as sole reliance on chemical controls increased (Casagrande
1987). These included the use of early maturing varieties of potato and crop rotation.

Recently, Lashomb and N9 (1984) and Wright (1984) have shown that crop rotation

2

can substantially reduce CPB pest problems, however, rotation is not commonly
practiced In many potato growing regions.

The impact of natural enemies of the CPB has been considered to be Inadequate for
effective suppression of pest populations (Harcourt 1964). However, as with most
research on biological control of agricultural pests, studies of the impact of CPB natural
enemies have been conducted within the constraints of the current crop production
system. Many of these cropping practices have evolved during a period of heavy
pesticide use. The evolution of agricultural production systems has led to changes In
agroecosystems that frequently disrupt the life systems of natural enemies. To fully
evaluate the potential of predators. parasitolds, and pathogens suppressing insect posts,
It is important to study their dynamics in a broader arena than current production
systems. This can be accomplished through studies on the temporal and spatial dynamics
of the natural enemy species as well as studies on its Interactions with the Insect pest.
This focus must expand the system's boundaries to Include alternative hosts and their
habitats, and feeding and overwintering sites.

This study represents the first steps In this process of exploring the potential and
developing and integrating biological controls of the CPB into the design of future potato
production systems. The natural mortality of the CPB was evaluated under a variety of
conditions, which encompassed both spatial and temporal differences. These Included
both early and late plantings of potato in the northeast and north central regions of the
US, and areas with high and low regional population pressures. Variations In natural
mortality were examined and the role of natural enemies was Investigated. As a result of
this population study, some aspects of the life systems of three individual natural enemy
species were explored. These included: the biology and seasonal dynamics of the carabid,
Lebia grandis Hentz, predation of the CPB by the coccinellid, Coleomegilla maculata
DeGeer and fungistatic effects of soils on the fungal pathogen, Beauveria bassiana

3

(Bals.) Vuill. These studies are presented in the following four manuscripts, preceded

by a general review of pertinent literature.

LITERATURE REVIEW

Many aspects of the biology and economic importance of CPB have been Investigated
since the discovery of this insect in 1811. Due to the severity of the CPB pest problem
worldwide, this is one of the most lntensively studied insects. In a computerized
literature search conducted In 1986, more than 900 citations were available for this
insect between 1975 and 1985 (Drummond pers. comm.). In this review, I will
describe the life cycle of the CPB and discuss those studies concerning the population
dynamics of the CPB and the role of endemic natural enemies. For a comprehensive
coverage of much of the recent research concemlng the biology and management of CPB,
readers are referred to Lashomb and Casagrande (1981) and Ferro and Voss (1985).

WE!

CPB overwinters in the adult stage, generally emerging In mid to late May in Rhode
Island and Michigan. Lashomb et al. (1984) developed a predictive model for CPB
emergence based on the accumulation of heat units In the soil. 0n emergence. CPB adults
walt in search of host plants. or if sufficiently stewed, fly (Caprlo 1987). The CPB Is
a primary past of potatoes, tomatoes. and eggplants and also feeds on several wild
solanaceous plants (Hsiao 1985). Overwintered beetles mate in the spring, and females
oviposlt eggs in masses on the underside of the host plant leaf. After hatching. the insect
completes four larval instars. all of which feed on the foliage of the potato plant. When
mature. the prepupae drop to the ground and burrow into the soil to pupate. Logan et al.
(1986) quantified the temperature dependent development of the CPB, and based upon
their results, degree-day (base 10°C) requirements for eggs, the four larval Instars,
and pupae (+prepupae) are: 72. 36, 32, 37, 69, and 176, respectively.

Summer adults emerge in July and August in Rhode Island and Michigan and feed on
potato foliage. Voss et al. (1988) determined that In western Massachusetts the

4

5

majority of females emerging before July 25 oviposlt. contributing to the second
generation of CPB larvae. Those females emerging after this time are in reproductive
diapause, and after feeding burrow into the soil to overwinter. Thus the timing of
emergence of summer adults determines the magnitude of the second generation. In most
years In Rhode Island, the CPB appears capable of completing a large second generation.

In Michigan, the second CPB generation Is usually small (Grafius, pers. comm.).

W

Harcourt (1963, 1964) and Logan (1981) Investigated the spatial pattern of CPB
on potatoes and developed a sampling plan for adults, eggs and larvae. Harcourt (1964)
recommends sampling 100 to 200 plants per sample data to estimate densities of CPB
life stages. Logan (1981) presents the number of stems necessary to sample for set
levels of precision as a function of density.

Harcourt (1971) investigated the population dynamics of the CPB in eastern
Ontario based on 10 sets of life table data collected over nine years. He found survival of
summer adults or starvation-stimulated emigration to be the key factor responser for
numerical change from generation to generation. Starvation of large larvae Is a key
factor of less importance. Harcourt (1971) reported cannibalism of CPB eggs by adults
to be the largest source of mortality for oviposited eggs. and rainfall as the only
measurable source of mortality for small larvae. He concluded that mortality due to
predators was so small as to be obscured by sampling error. Harcourt (1971) found
survival of all Immature stages to be density-independent. except pupal survival, which
was positively density-dependent (pupal survival Increased with pupal density). He '
attributed this relationship to the failure of the tachinld parasitold Myiopharius
doryphorae Riley to respond to changes in host density. Harcourt's conclusion was that
nothing regulates CPB densities in potatoes except CPB density Itself when defoliation
results in total depletion of the food source.

W

Many endemic natural enemies have been reported attacking the CPB. From 1869
to 1876, Riley listed 26 natural enemies of the CPB in the US; Bethune (1872)
describes 22 (T able 1). and Wegorek (1955) lists 59 species of invertebrate predators
and parasites. In addition to invertebrate predators, Karg and Mazur (1969) found CPB
adults and larvae to be an Important component In the diets of three species of
amphibians lnhabiting potato fields. Studies attempting to assess the Impact of natural
enemies on the CPB have been focused on the tachinid parasitold, M. doryphorae , the
fungal pathogen, B. bassiana . and the pentatomid predators, Peril/us bloculatus F. and
Podlsus maculiventris (Say). My preliminary observations suggest that the foliar
searching carabid, L. grandis , and some coccinellids may also contribute significantly to
CPB mortality in Rhode Island and Michigan.

Myiopharius doryphorae Riley

The CPB is the sole host reported for M. doryphorae . Adults Iarviposit in the
second, third and fourth instars of the CPB, but the parasitic maggots do not start
development until the fourth Instars enter the soil to pupate (T amaki et al. 1983). The
parasitold kills Its host during the prepupal stage and a characteristic 'mummy‘ Is
formed when the maggot pupates within Its host's prepupal skin. M. doryphorae adult
emergence lags several days behind that of nonparasltlzed CPB. and adults have a
preovlposltion period of ca. 7-10 days at 25°C (1' amakl et al. 1982). The
overwintering stage of M. doryphorae is unknown.

Riley (1869) reported M. doryphorae killing 10% of the second larval generation
of CPB in Missouri and 50% of the third generation. Riley's observations on the
effectiveness of this parasitold have been confirmed by Kelleher (1966), Harcourt

(1971), and Tamaki et al. (1983). Although Kelleher found a significant correlation

7

Table 1. Natural enemies of the Colorado potato beetle endemic to North America
reported by Riley and Bethune (1869-1877).

 

Scientific Name

Stage attacked

 

Pha lang Ida
Phalanglum spp.
He ml pte ra
Reduviidae
Harpaclor cinctus
Sines diadema
{-Reduvlus raptaforius)
Pentatomidae
Podisus macullventris
(-Arma splnosa)
Peri/[us bloculatus
P. circumcinctus
Euschlsfus variolarlus
(-E. puncfipes)
Colooptera
Ciclndelidae
Tetracha vlrglnr'ca
Carabldae
Lebia grandis l-ientz

Lebia atriventrls
Calasoma calidum
Pas/machum elongatus
Harpalus callginosus
Staphylinidae
Philonthus spp.
Cocclnellidae
Coleomegilla maculata
(- Hippodamia maculata)
Cocaine/Ia novemnotata
Hippodamla frldeclmpunctafa
H. convergens
H. glacialis
Anatr’s quindeclmpunctata
(-Mysla 15-punctata)
DI pte re
Asilldae
Pmmachus bastardii
Tachinidae
Mylopharus doryphorae
(-Doryphorophaga doryphorae
-Lydella doryphorae)
H yrcenoptera

Polisfes rubiginosus

preys on eggs and larvae

preys on larvae

preys on eggs and larvae

preys on larvae

preys on larvae

preys on eggs and larvae. and
parasitizes pupae

preys on eggs and larvae

preys on larvae

preys on eggs and small larvae

preys on adults

parasitizes larvae

preys on larvae

 

8

between CPB pupal mortality and parasitism, there was no correlation between larval
density and percent parasitism. Harcourt found pupal parasitism to be Inversely density
dependent. suggesting that M. doryphorae did not respond to changes in host density.
Kelleher suggests that M. doryphorae 's main limitation in controlling CPB is Its lack of
synchrony with Its host. In Manitoba. adult flies were most abundant as the second

larval generation were declining. The majority of the first larval generation and the
early portion of the second larval generation escaped attack. Tamakl et al. (1983) also
reported the impact of M. doryphorae to be limited by its low abundance during the first
generation of CPB In Washington, although maximum parasitism of the second generation
reached 75%. This species has also been found parasitizlng the CPB in Mexico (Logan et
al. 1985).

Beauveria bassiana (Bals.) Vuill.

The endemic biological control agent most intensively studied Is the entomopathogen
B. bassiana This fungus is the causal agent of the white muscardine disease, which
Infects more than 200 insect hosts (Llpra 1967). The reported North American hosts
of this fungus are presented in Table 2. All stages of the CPB, except eggs, are
susceptible to B. bassiana infection.

The germinating conidia of B. bassiana penetrate directly through the cuticle of its
hosts (Cooke 1977). Once in the haemocoel, the mycelium breaks Into hyphal bodies
which circulate and proliferate in the haemolymph. The multiplication of fungal cells
retards and obstructs circulation. Disease symptoms and death are thought to be caused
by toxins produced by the Invading fungus (Ferron 1978). After death. the fungus
reverts to a filamentous form and ramifies throughout the Internal organs and body of
the insect. Under favorable conditions hyphae emerge through the integument and
produce conidiophores and conidia (Cooke 1977).

9

Table 2. Known North American hosts of Beauveria bassiana from reports of natural

incidence In the field.

 

 

Scientific Name Common Name Reference
Heteroptera
Lygaeldae
Blissus leucopferus chinch bug Ramoska & Todd 1985
Miridae
Lygus IIneolarIs tarnished plant bug Humber 1986
Coleoptera
Cardaidae
Lebia grandis Madge 1967
Pythidae
Pyrho sp. Humber 1986
Cocclnellldae
Coccine/Ia septempunctafa 7-spotted ladybird Cartwright at al. 1982

Coleomegilla maculata
Chrysomelidae

Cerofoma trifurcata

Diabmtfca undecimpunctafa

Leptlnotarsa decemlineafa
Curculionldae

Araecen‘s fasciculatus

Chaloodermus aeneus

Conatachelus nenuphar

Curcullo caryae

Diaprepes abbreviatus
Hypera brunneipennls
Otlorhynchus sulcatus
Rhinocyllus conlcus
Sitona hlspidulus
Scolytidae
Dendroctonus fronts/is

D. pondemsae

D. rufipennes
Dryococtis confusus
fps sp.

Scolytus scolyrus

Lepldoptera
Pyralidae
Ostrinla nubile/Is
Tortricldae
Charistoneura sp.

spotted ladybird

bean leaf beetle

southern corn rootworm
or spotted cucumber beetle
Colorado potato beetle
coffee bean weevil

cowpea curculio

plum curculio
pecan weevil

Egyptian alfalfa weevil
black vine weevil

clover root curculio

southern pine beetle

western bark beetle
elm bark beetle

European corn borer

Humber 1986

Marrone at al. 1983
Humber 1986

Humber 1986

Humber 1986

Humber 1986

Humber 1986

Gottwald a Tedders
1982

Beavers et al. 1983

Johnson at al. 1984

Humber 1986

Dowd 8. Kok 1983

Quinn 8. Hower 1985

Pabst & Sikorowskl
1980

Humber 1986

Humber 1986

Whitney et al. 1984

Doberski a Tribe 1980

Humber 1986
Humber 1986

Table 2, continued.

10

 

 

Scientific Name Common Name Reference
Noctuidae
Hellothls virescens Tobacco budworrn Humber 1986

H.268

Laslocampidae
Malacosoma emericanum
M. disstrla

bollworm/corn earworm/ Smith et al. 1981
tomato frultworm

Eastern tent caterpiller Humber 1986
forest tent caterpiller Stark a Harper 1982

 

11

B. bassiana has been mass produced in Europe and the Soviet Union for control of
the CPB. In the Soviet Union, 8. bassiana (Boverin) sprayed In combination with a
sub-lethal dose of insecticide (which weakens the insect host) has been successful for
CPB control (Ferron 1981).

B. bassiana has been studied for several years In Rhode Island. This work Included
monitoring Its natural Incidence In CPB populations (Clark 1980) and evaluating
several different spray formulations and methods of conidlal application (Roberts et al.
1981). This pathogen has consistently been most effective late In the growing season
(Lean pers. comm). It caused only negligible mortality to the first generation. but
over 58% mortality to the second larval generation In Clark's (1980) natural Incidence
study. Similar results were obtained by spraying this pathogen on the foliage.
Therefore. this increased efficacy is probably not due to Inoculum build-up throughout
the season, but rather to changes In the ablotlc environment or in CPB susceptibility.

Effects of some environmental factors on Infection and disease development have
been elucidated. Temperature affects the rate of disease development directly and
Indirectly. Clark (1980) found the time to death of inoculated CPB larvae and adults to
be a function of inoculum concentration and temperature. Indirectly, temperature
influences the time between successive molts CPB larvae, and hence the ability of larvae
to shed germinating conidia at ecdysis.

Humidity has a greater Influence on disease development than temperature (Ferron
1978). Walstad at al. (1970) observed no germination of B. bassiana conidia at
relative humidities below 97.5%. Once conidia have successfully penetrated the host
Integument, ambient humidity Is no longer a factor until sporulation.

Sunlight may also be a limiting factor in B. bassiana activity In exposed portions
of the potato canopy. Clerk and Madelin (1965) showed that sunlight reduces spore
viability. Tourmanoff (1933) showed that spores were Inactivated by periods of

sunlight In excess of 3 hours.

12

The humidity and sunlight limitations on B. bassiana spore viability and
germination have stimulated research In the interactions between this pathogen and the
CPB In the soil environment. Watt and Lean (1984) found significant reductions
(74% first generation and 77% second generation) In CPB adult populations due to soil
applications of B. bassiana conidia.

The fungistatic pressure of soils on B. bassiana varies with soil type and season
(Sharmov and Kalvish 1984). Funglstasis, the Inhibition of fungal spore germination
in natural soils, Is thought to be an adaptive characteristic for fungi. limiting
germination of spores to times when sufficient resources are available for complete
development (Lockwood and Filonow 1981). Although the viability of B. bassiana
conidia In soil decreases as temperature and soil moisture Increase. their half-lives are
still relatively long (120 days under normal temperature and humidity conditions)
(Lingg and Donaldson 1981). Greater understanding of the ecology of B. bassiana In the
soil and the Interactions of CPB with the soil mlcrohabitat ls necessary If any potential

is to be found for manipulating this environment to increase CPB mortality.

Pumas bloculafus F.

The two spotted stink bug. P. bloculafus, Is considered the most Important
predator of the CPB In most potato growing areas of the US. (Riley 1869, Knight 1923.
Tamakl and Butt 1978) and Canada (Bethune 1911, Franz 1957, Harcourt 1971). The
North American distribution of P. bioculatus extends east through Ontario, New York,
and Quebec; south to Florida and Mexico and west to the Pacific (McPherson 1982). P.
bloculatus has not been reported In potato growing regions In New England. P.
bioculatus has a fairly limited host range (T able 3), with the CPB considered as Its
predominant prey.

Overwintered P. bioculatus adults emerge In the early spring and congregate In
potatoes as the first CPB's appear (Knight 1923). Females lay their eggs In masses (ca.

13

Table 3. Known prey species of Peril/us bioculatus.

 

Scientific Name

CommonName

Reference

 

Coleoptera
Cocclnellidae
Epilachna varivestis
Chrysomelidae
Acalymma vlttaia
Chrysomela scripfa

Leptinotarsa decemlineata
Pyrrhalta queola
Trirhabda canadensis
zygogramma heterothecae

Z. sufuralis

Lepldoptora
Liparidae
Unidentified species
Noctuidae
Mamesrra plcfa

Mexican bean beetle

Stripped cucumber beetle
cotton leaf beetle

Colorado potato beetle
elm leaf beetle
golden rod beetle

Howard 8 Landis 1936

Marsh 1913

Burkot & Benjamin
1979

Knight 1922

Beaver 1986

Knight 1922

Altieri 8 Whitcomb
1979

Altieri a Whitcomb
1979

Nash 1912
Marsh 1913

 

14

14 eggs per mass) on the upper surface of the potato leaves. Eggs hatch In 8 days at
24°C and the primarily non-feeding first instars remain on the egg cluster for ca. two
days (22-24°C) before molting to second instars and searching for prey (Tamakl and
Butt 1978). Nymphs pass through four predacious Instars before moltlng to adults.
Total nymphal development requires 18.2 days at 24°C and 20.7 days at 22°C (T amakl
and Butt 1978).

Adults and fourth and fifth Instars of P. bloculatus feed on all life stages of CPB
Including adults. Third instars feed on all Immature stages of CPB, but second Instars
prefer eggs and newly-hatched larvae (Knight 1923). Tamakl and Butt (1978)
quantified consumption rates for all nymphal Instars. Though fifth Instars consumed an
average of 39 CPB eggs per day when reared solely on CPB eggs. they consumed only 0.2
large CPB larvae per day.

P. bloculatus completes two generations per year In the northern U.S. (Knight
1923). The onset of diapause in 14 day-old adults ls triggered by photoperlods of less
than 15 hours (Shagov 1977b). Extremely high overwintering mortality has been
reported In Minnesota (95%, Knight 1923) and Europe (90-96%. Jermy 1980).

Since the late 1920's, many attempts have been made to establish and study P.
bloculafus In Europe (Jermy 1980). Although temperature and humidity regimes
favored by this predator (Shagov 1977a, 1977c) exist In many European countries, the
species Is not established (Jermy 1980). Jenny (1980) suggested that direct control
of CPB with repeated mass-rear and release programs had little potential because of
cost, the predator's susceptibility to Insecticides, and the Inability of the predator to
keep CPB populations below an economically acceptable level. Tamakl and Butt (1978)
and Harcourt (1971) also suggested that endemic populations of P. bloculatus in
Washington State and Ontario. respectively, were Ineffective in suppressing CPB
populations below economically damaging levels.

15

Podlsus macullventrls (Say)

Unlike P. bioculafus . the spined soldier bug, P. macullvenfrfs , Is found In all
potab growing regions In North America, and It has a very broad host range. McPherson
(1982) lists over 100 prey species for this predator (T able 4). The more commonly
reported prey Include the CPB, Mexican bean beetle (Epilachna varivestrls ), elm leaf
beetle (Pyrrhalta Iafeola ), greater wax moth (Galleria mellanella ). fall webworrn
(Hyphantria cunea ), bollworm (Heliothis zea ). soybean looper (Pseudoplusla nl ),
cabbage looper (TrichOpIusia nI ), and eastern tent caterpillar (Malacosoma
amerlcanum ).

Similar to P. bloculatus. P. maculiventris overwinters In the adult stage In the
humus layer and leaf litter (McPherson 1982). Esselbaugh (1948) reported that adult
females overwinter in a non-gravid state and mating occurs in the spring, three to four
days after emergence. Mukerjl and LeRoux (1969a) found that continued mating Is not
necessary for the production of fertile eggs. but the fecundity of mated females Is a
function of temperature and food Intake. The number of eggs per mass Increased from
18.5 at 21°C to 31.4 at 27°C. although egg masses per female decreased slightly with
increasing temperature. Eggs hatch In ca. 9-10 days at 21°C or 5 days at 27°C
(Couturier 1938).

P. maculfventris nymphal development ls influenced by temperature. prey
consumption, and sex. Couturier (1938) reported that males develop faster than
females (1-3 days) and total nymphal development Is completed in ca. 27-30 days at
23°C. Landis (1937) and Drummond at al. (1985) found that prey species strongly
influence both development rates and survival of nymphs. Drummond et al. (1985)
reported the CPB to be an inferior host in comparison with the Mexican bean beetle, the
greater wax moth. and the eastern tent caterpillar in that both the development rate and

survival of P. macullventris nymphs are significantly less when reared on CPB larvae.

16

Table 4. Known prey species of Podisus maculiventrls (Say). (From McPherson 1982)

 

Scientific Name

ComrnonName

 

Ephemoroptera
Unidentified species

Orthoptera
Acrldldae
Melanoplus femurrubrum (DeGeer)
Gryllidae
Gryllus assimilis (Fabricius)
Phasmatidae
Diapheromera femorata (Say)

Hemlptera
Miridae
Lygus Ilneolaris (Palisot de Beauvois)
Tlngidaa
Gargaphla solani Heidemann
Pentatomidae
Acmstemum hilare (Say)
Apafeticus cynicus (Say)
Euschfstus tristr’gmus (Say)
Nezara viridula (Linnaeus)
Podlsus maculiventris (Say)

Homoptera
ae
Clastopfera obtuse (Say)
Philaenus spumanus (Linnaeus)
Aphldidae
Acyrthosiphon plsum (Harris)
Unidentified species

Coleoptora
Scarabaeidae
Unidentified species
Lampyridae
Unidentified species
Coccinellidae
Adalia bipuncfata (Linnaeus)
Anatis quindecimpuncfata (Olivier)
Cocaine/Ia sp.
Coleomegilla maculafa (DeGeer)
Epllachna varivestls Mulsant
Unidentified species
Tenebrionidae
Bothrotes arundinls (Le Conte)
Tenebrfo molifor Linnaeus

Redlegged grasshopper
Field cricket
Walkingstlck

Tarnished plant bug

Eggplant lace bug
Green stink bug

Dusky stink bug
Southern green stink bug
Splned soldier bug

Alder splttlebug
Meadow splttlebug

Pea aphid

Two-spotted lady beetle

Mexican bean beetle

Yellow mealworm

1 7
Table 4. continued.

 

 

Scientific Name Common Name
Chrysomelidae
Altlca chalybea Illiger Grape flea beetle
Anomoea flavokansiensis Moldenke
Chrysomela scripta Fabricius Cottonwood leaf beetle
Crlocen‘s asparagl (Linnaeus) Asparagus beetle
Diabrotr‘ca undecimpunctata howardl Barber Spotted cucumber beetle
Lama trilineata (Olivier) Threelined potato beetle
Leptlnotarsa decemlineata (Say) Colorado potato beetle
Nodonota sp.
Pyrrhalta luteola (Muller) Elm leaf beetle
Systena elongata (Fabricius) Elongate flea beetle
Unidentified species
Zygogramma heterothecae Linell
Zygogramma suture/is (Fabricius)
Curculionldae
Hypera postlca (Gyllenhal) Alfalfa weevil

Unidentified species

Lepldoptera
Pyralidae
Anagasta kuahniella (Zeller)
Galleria mellonella (Linnaeus)
Ostrlnia nubilalls (Hubner)
Psoroslna hammondl (Riley)
Udaa rublgalls (Guenee)

Olethreutidae
Ancylls comptana fragarlae (Walsh 5 Riley)
Laspeyresla pomonella (Linnaeus)
Spilonota ocellana (Denis a Schiffermuller)
Tortricldea
Archlps argyrospllus (Walker)
Archlps ceraslvoranus (Fitch)
Archlps fervr'danus (Clemens)
Argymtaenla velutr'nana (Walker)
Pandemls canadana Kearfott
Pandemls Iampmsana Robinson
Coesldae
Cossus cossus Linnaeus

Depressarla pastlnacella (Duponchel)
Yponomeutidae

Plutella xylastella (Linnaeus)
Coleophoridae

Coleophora serrate/la (Linnaeus)

Mediterranean flour moth
Greater wax moth
European corn borer
Appleleaf skeletonizer
Celery leaftler/
greenhouse leaftler

Strawberry leafroller
Codling moth
Eyespotted bud moth

Fruittree leafroller
Uglynest caterpillar

Oak webworm
Rerbanded leafroller

Parsnlp webworm
Diamonmack moth

Birch casebearer/cigar
casebearer

l 8
Table 4, continued.

 

Scientific Name

ComrnonName

 

Gracllariidae
Caloptilia syringe/la (Fabricius)
Geometridae
Paleacrita vemata (Peck)
Pleuroprucha lnsulsan’a (Guenee)
Unidentified species
Ctenuchidae
Lymire edwardsll (G rote)
Archtiidae
Hyphantrla cunea (Drury)
Noctuidae
Alabama argillacea (Hubner)
Alypia octomaculata (Fabricius)
Amphipyra tragopoginus (Linnaeus)
Antlcarsla gemmatalis Hubner
Ceramica picta (Harris)
Euxoa scandens (Riley)
Heliothis virescens (Fabricius)
Heliothis zea (Boddie)

thhophane antennata (Walker)
Plathypena scabra (Fabricius)
Pseudoplusla includens (Walker)
Spodoptera exigua (Hubner)
Spodoptera frugiperda (J.E. Smith)
Trlchoplusla nl (H ubne r)
. Unidentified species
Notodontidae

Datana ministra (Dru ry)
Lymantriidae

Orgyia Ieucostigma (J.E. Smith)

Unidentified species
a

Malacosoma amerlcanum (Fabricius)

Malacosoma califomicum pluviale (Dyar)
Saturnildae

Anisota virginiensis (Dru ry)
Pieridae

Pieris rapae (Linnaeus)

Phoebis sp.
Papilionidae

Papilia cresphontes Cramer

Papillo polyxenes asterius Stoll

Danddae
Danaus plexippus (Linnaeus)

Lilac leafminer

Spring cankerworm

Fall webworm

Cotton leafworm
Eight-spotted forester

Velvetbean caterpillar
Zebra caterpillar
White cutworm
Tobacco budworm
Bollworm/corn earworm/
tomato frultworm
Green frultworm
Green cloverworm
Soybean looper
Beet armyworm
Fall armyworm

Cabbaoelooper

Yellownecked caterpillar

Whitemarked tussock
moth

Eastern tent caterpillar

Pinkstriped oakworm

Imported cabbageworm

Ormgedog
Black swallowtail!
parsleyworm

Monarch butterfly

l 9
Table 4, continued.

 

Scientific Name

ComrnonName

 

Dlptera

Tephflfldae

Rhagoletls pomonella (Walsh)
Anthomyiidae

Hylemya antique (Meigen)
Muscidae

Musca domestica Unnaeus
Tachinidae

Unidentified species

Hymenoptera
Diprionidae
Diprlon slmilis (Hartig)
Neodiprion taedae linearis Ross
Tenthredinldae
Fenusa pusilla (Lepeletier)
Pristophora gen/culata (Hartig)
Pristlphora rifipes Lepeletier
Tethlda cordlgera (Palisot de Beauvois)
Formicidae
Camponotus sp.
Vespidae
Unidentified species

Apis mellifera Linnaeus

Apple mascot
Onion maggot
House fly

Introduced pine sawfly
Loblolly pine sawfly

Birch leafminer
Mountain-ash sawfly

Blackheaded ash sawfly

Carpenter ant

Honeybee

 

20

Feeding preferences of P. maculiventris nymphs are similar to those of P.
bioculatus ; the smaller nymphs prefer small hosts while the larger nymphs and adults
feed on all prey life stages (Mukerjl and LeRoux 1969a). Waddill and Shepherd (1975)
reported that due to the selection of larger prey Individuals. the number of prey
consumed per predator may decrease with nymphal age. However, older nymphs are
able to subdue prey more quickly and consume food faster than younger nymphs
(Mukerjl and LeRoux 1967a)

P. maculiventnis Is considered a timid predator. Morris (1963) reported prey
defense and density to strongly Influence predation rates of adults feeding on H. cunea
larvae. Predation of sluggish prey was greater than that of active prey. However, lwao
and Wellington (1970) found that active prey (Western tent caterpillars) were more
attractive to the predators than sluggish prey. thus for smaller prey less capable of
defense, predation increased with prey activity. Morris (1963) and Mukerjl and
LeRoux (1969b) found predation rates of adult P. maculiventrls to decrease with age.

The seasonal dynamics of P. macullventrls have not been followed in the field. The
predator probably completes two generations per year In the southern portion of Its
range (Rhode Island) and one generation per year In Michigan and northward
(McPherson 1982). Its presence in potato fields in Rhode Island is not detectable until
the latter part of the growing season (Casagrande, per. comm), hence Its potential for
biological control of the CPB may be limited. Drummond et al. (1985) simulated
development of P. maculiventris and the CPB under average Rhode Island temperatures
and found the predator to have a considerable developmental disadvantage in the early
season. CPB eggs and larvae develop more rapidly than P. maculiventris with the cool
spring and early summer temperatures.

Several attempts have been made to Introduce P. maculiventris Into Europe
(Schwartz 1941, Bjegovic 1971, and Tadic 1975). and like P. bioculatus

introductions, these have been unsuccessful.

21

Lebia grandls Rant:

The foliar searching carabid, L. grandls was first reported as a predator of CPB by
Riley In 1872. In 1936, French entomologists collected L. grandls along with other
CPB natural enemies In upper New York State to study their potential for controlling the
CPB In Europe (Bruneteau 1937). Chamboussou (1938) described the biology of L.
grandis and succeeded in mass rearing the predator on the CPB. The life cycle of the
genus Lebia Is unusualin that while the adults are predaceous on eggs and larvae of
chrysomelids, the larvae are ectoparasitoids on pupae of the same host (Madge 1967).

The CPB Is the only reported host of both the adult and immature stages of L.
grandls (Madge 1967). Adult females lay their eggs singularly In the soil. The newly-
hatched larvae burrow Into the soil In search of CPB pupae. After locating Its host. it
feeds as an external parasitold. becoming less mobile as It feeds (Chamboussou 1938).
Chamboussou (1939) noted that In the laboratory successful parasitism is achieved by
parasitic larvae released in a CPB pupatlon chamber within 30 minutes after CPB
prepupae burrow into the soil. After feeding, the bloated first lnstar molts Into a non-
feeding second stage larva, then molts Into a pupa. At 25°C, L. grandls develops from
first instar to adult In 22 to 25 days (Chamboussou 1938).

No reports of field releases of L. grandis have been published, although
Chamboussou (1938) suggested that it had potential for biological control of CPB. L.
grandls Is one of the more abundant egg predators In potato research fields In Rhode
Island, and specimens In the MSU, Department of Entomology Insect Museum indicate
that it Is widespread throughout the state of Michigan. No research studies concemlng L.
grandis have been published since Chamboussou (1939).

22

Cocclnelllds

Much research has been focused on the Interactions between coccinellids and aphids
In potato fields (Shands and Simpson 1972; Mack and Smilowitz 1978, 1980. 1982a,b;
Mack et al. 1981; Shanda et al. 1972 a.b.c; Tamakl 1981) with little mention of the
fact that several species also feed on the CPB. Karg (1976) reported higher mortality
rates for CPB eggs and larvae In areas close to shelterbelts In potato growing areas In
Poland. and attributes this partially to the coccinellids which overwinter in the these
protected areas. Specific species were not reported. Trojan (1968) lists several
species of aphidophages, including nine species of coccinellids, found In potatoes in
Poland. and reports an Inverse relationship between the mortality of CPB eggs and the
ratio of aphidszaphldophagas. He concludes that aphids are the preferred food of these
predators, but as aphids decrease, they switch to CPB eggs for prey. Of the nine spades
of coccinellids listed by Trojan, only one. Hippodamia tridecimpunctata L., has been
reported to feed on the CPB in North America (Bethune 1872). Seven different species
of coccinellids have been sampled In Rhode Island potato fields. and eight species In
Michigan fields. Of these, the spotted ladybird, Coleomegilla maculata DeGeer was most
frequently observed feeding on CPB eggs.

C. maculata Is a polyphagous predator commonly reported feeding on aphids In
many cropping systems including potatoes. The reported prey species and food of C.
maculata Is presented in Table 5. In addition to Insect prey, this coccinellid has been
observed to feed considerably on pollen, and Smith (1960) showed that larvae of C.
maculata can complete development when reared solely on this food.

Wright and Laing (1978) and Obrycki and Tauber (1978) describe the
temperature-dependent development of this predator and Its braconid parasite, Perilltus
coccinellse- (Shrank.) Wright and Laing (1978) found that fecundity (avg. 191.5 eggs
per female) but not longevity (avg. 82.3 days) varies with temperature. Smith (1961,
1965) found C. maculata longevity, fecundity and development to vary with diet.

23

Table 5. Known prey species and food of Coleomegilla maculata.

 

 

Scientific Name Common Name Reference
Plant pollen and nectar
Barbarea vulgaris yellow rocket Conrad 1959
Betula populifolla‘ gray birch Smith 1961
Cannabis safi‘va1 hemp Smith 1961
Carpinus caroliniana1 hornbean Smith 1961
Juglans clnerea1 butternut Smith 1961
Prunus perisica pewh Putman 1984
Taraxacum offlclnale dandelion Conrad 1961
Typha Iatifolia1 cat-tail Smith 1961
Zeamays corn Britton 1914
Acari
Tetranchldae
Tetranchus canadensis four-spotted spider mite Putman 1964
Heteroptera
Lygaeldae
Blissus Ieucopterus chinch bug Conrad 1959
Miridae
Trigonotllus rublcornis Conrad 1959
Pentatomidae
Podisus placidus Conrad 1959
Reduviidae
Shea diadema Conrad 1959
Homoptera
Aphididae
Acrythosiphon dirhodum Gordon 1985
A. pisum (-Macrosiphum pisl) pea aphid Conrad 1959
Aphis gossypil melon aphid Conrad 1959
A. rumicls Gordon 1985
Brevicoryne brasslcae cabbage aphid Conrad 1959
Cryptomyzus ribis currant aphid Conrad 1959
Hyadaphis erysimi turnip aphid Gordon 1985
Macmsiphum avenue English grain aphid Gordon 1985
M. euphon’biae potato aphid Gordon 1985
Myzus persicae green peach aphid Mack 8
Smilowitz 1980
Nearcfaphis crataegifoliae Gordon 1985
Pemphigus bursarius lettuce root aphid Gordon 1985
Schizaphls gramminum greenbug Conrad 1985
Phylloxerldae
Pineus strobi pine bark adeigld Gordon 1985

Psyiiidae
Trioza diospyrl

persimmon psyiia

Conrad 1959

Table 5. continued

24

 

 

Scientific Name Common Name Reference
Coleoptera
Chrysomelidae
Chrysomela scripta cottonwood leaf beetle Conrad 1959
Crioceris asparagl asparagus beetle Conrad 1959
Leptlnotarsa decemlineata Colorado potato beetle Riley 1869
Coccinellidae
Coleomegilla maculata spotted ladybird Plenhowskl 1965
Cycloneda munda Conrad 1959
Lepldoptera
Archtiidae
' Hyphantria cunea fall webworm Warren 8 Tadic
1967
Noctuidae
Heliothus zea bollworm Whitcomb 8 Bell
1984
Pyralidae

Ostrinla nubilalis

European corn borer

Conrad 1959

 

lFrom laboratory studies.

25

Although consumption rates have been determined for this predator In the laboratory
(Mack and Smilowitz 1982), little Is known of Its population dynamics or the Impact on
prey species in the field. Conrad (1959) did track C. maculata predation of European
corn borer eggs In com fields in Delaware by examination of fecuia. Conrad also
surveyed many crop fields in Delaware on a weekly basis and reported C. maculata
adults present In all crops. but found larvae only In clover, alfalfa, and aphid-infested
corn. Conrad estimated four to five generations per year Ior C. maculata In Delaware,
but as with other mobile predators. their seasonal dynamics Is difficult to ascertain.

Ground-dwelling carabid:

Surveys of ground-dwelling carabid spades have been conducted by pitfall
trapping in potato fields in the US. (Boiteau 1984, Evans unpublished data). Europe
(Schemey 1959) and the Soviet Union (Sorokin 1981). Studies attempting to relate
carabid populations with CPB mortality have been limited to Germany (Thiele 1977).
Poland. and the Soviet Union (Sorokin 1981). Schemey (1959) conflned two species of
Carabus common In potato fields in Bavaria. with cohorts of CPB eggs on potatoes ln
containers and In 4 m2 enclosed areas. He found a 73.95% reduction in ope larvae and
pupae after 3340 days In both cases. and reported significant Increases in potato yields
over treatments with no CPB control. The densities of carablds used In Schemey's
experiments were typical of those found in the research areas. but were considerably
higher than those found in most potato growing areas In the rest of the country (T hlele
1 977).

Sorokin (1981) used three criteria to rank commonly encountered carabid species
for their importance as predators of the CPB In Irrigated and nonirrigated potatoes:
estimates of their relative abundance In potato fields. analysis of gut contents. and
consumption rates. He determined the three species. Pterostichus cupreus, Ophones
rufipes, and Brocus uphalotes to be the most effective predators. Although these

26

particular species have not been reported In cropland In North America. other species
within the genera Carabus (Rivard 1964) and Pterostltchus (Evans. unpublished data)
have been recorded.

Summary

There appears to be little potential for control of the CPB with endemic natural
enemies under conventional stepping systems. Several natural enemy species have been
reported to be fairly abundant late in the growing season. after considerable CPB damage
has been sustained. This late season activity may be a result of a build-up of natural
enemy populations. or it may be due to favorable environmental conditions.

L. grandis and M. doryphorae are specific predators and parasitoids of the CPB.
The other natural enemies monitored In this study have alternate hosts or prey. The
dynamics of these natural enemy populations may be dependent on the availability of

alternate prey or habitats.

MANUSCRIPT 1 .

Stage-Specific Survival of the Colorado Potato Beetle
In Early and Late-Planted Potatoes
In Rhode Island and Michigan

ABSTRACT - The densities of adult and immature Colorado potato beetles (CPBs) and
their predators were sampled in both early and late planted potatoes at one research site
In Rhode Island and two sites In Michigan from 1985-1987. In each plot CPB adults and
large larvae were sampled to determine the percentage Infected by the entomopathogen.
Beauveria bassiana. and prepupae were collected to determine the percentage parasitized
by the tachinid. Myiopharius doryphorae. For each of eight plots. seasonal density
estimates and stage-specific survival rates of four Immature stages (eggs. small larvae.
large larvae. and pupae) of CPB were calculated. Key factor analysis revealed that the
large larval and pupal stages were the most highly correlated with total within-
generation survival. The pupal stage was the only stage for which survival was
significantly correlated with density. Pupai mortality was inverse density dependent.
and of the various factors responsible for pupal mortality. parasitism by the tachinid.
Myiopharius doryphorae. was most highly correlated. M. doryphorae parasitism
decreased with increased host density and was positively correlated with degree-day
accumulation.

Key factor analysis was conducted for the early and late planted potatoes
Independently. and egg survival was found to be the key factor In withingeneration
survival in early planted potatoes. Although no measured source of mortality was
significantly correlated with egg survival over all plantings. the incidence of
Coleomegilla maculata was Inversely correlated with egg and small larval survival

(total C. maculata prey) In Rhode Island alone. in 1987. the densities of egg masses

27

28

preyed upon by haustellate and mandibulate predators and the densities of the carabid
predator Lebia grandis were sampled. L. grandis densities were positively correlated
with the densities of mandibulate-preyed egg masses in both Rhoda island and Michigan.
The combined action of CPB egg and larval predators accounted for greater than 96%

mortality of this past in one Michigan research plot.

29

INTRODUCTION

Insecticides have been used intensively against the Colorado potato beetle (CPB)
since 1865 (Casagrande 1987). In the past 30 years this practice has resulted In high
levels of Insecticide resistance and more recently. ground water contamination (Forgash
1985. Dover and Croft 1986). CPB has demonstrated itself to be an extremely
adaptable insect. overcoming the resistance of wild potato plants within two generations
(Groden and Casagrande 1986). It Is evident that single control strategies will not
provide long-term solutions to CPB pest problems. Future pest management programs
for this past must rely on the Integration of cultural and biological controls.

Crop rotation greatly reduces CPB populations (Lashomb and Ng 1984. Wright
1984). and early recommendations for controlling CPB Included rotations and growing
early maturing and resistant varieties (Walsh 1865. Riley 1869. Bethune 1872).
These strategies are not currently practiced In many potato growing regions.

Many endemic natural enemies have been reported attacking the CPB. Riley lists
26 natural enemies of the CPB in the 0.8 (1869. 1871, 1872. 1873). Studies have
addressed the impact of the pentatomid predators. Podisus maculivenhis (Say)
(Drummond et al. 1985). and Peril/us bioculatus (Harcourt 1971. Tamakl and Butt
1978. Jenny 1980). the tachinid parasitold. Myiopharius doryphorae (Riley)
(Kelleher 1960. 1966. Harcourt 1971. and Tamakl at al. 1983). and the fungal
pathogen. Beauveria bassiana (Bals.) Vuill. (Clark 1980. Watt and Lean 1984) on
CPB populations under current potato production practices. Each investigation concludes
that the natural enemy does not adequately suppress CPB populations. However. most of
the species described by Riley have not been studied. Harcourt (1971) studied the
population dynamics of the CPB in Eastern Ontario. and concluded that natural enemies do
not regulate CPB populations. He found that CPB populations in unsprayed potato
research fields are only limited by starvation resulting from complete defoliation of

their host plant. Harcourt's study demonstrates the destructive potential of unchecked

30

CPB populations. and the limitations of natural enemies under current potato production
practices. However. more can be learned about the interactions of natural enemies and
the CPB and the potential for biological control of this past by looking beyond the
boundaries of current potato production system.

The objectives of this study were to Investigate the stage-specific survival of the
CPB under different planting practices. geographic regions. and regional population
pressures. and examine the role of endemic natural enemies in stage-specific mortality.
A comparative study was conducted with the expectation that we would gain Insight into
factors responsible for mortality of CPB by examining temporal and regional

differences.

MATERIALS AND METHODS
Silly—Silu-

Thls study was conducted from 1985-1 987 at two university research farms In
Michigan and one in Rhode island. The Michigan sites included the Michigan State
University Potato Research Farm In Montcalm County. Michigan (hereafter referred to
as the Montcalm site) which is In the center of Michigan's largest potato growing region.
and the Michigan State University Kellogg Biological Station in Kalamazoo County.
Michigan (hereafter referred to as KBS). The Rhode Island site was the University of
Rhode island's Research Farm in Kingston. Rhode island.

in 1985 research was conducted In both early and late planted potatoes in Rhode
island. and in late planted potabes at all other sites. In 1986 and 1987. both early and
late planted potatoes were established at all sites. All early potatoes were planted during
the first week or second week of May. and late potatoes were planted between June 19 -
June 25 In Michigan. and July 1 - July 4 in Rhode Island. In Rhode island, late potatoes
were planted In an area isolated from the earlier plantings in order to manage the
densities of colonizing CPB summer adults. At both of the Michigan sites. late potatoes

31

were planted adjacent to earlier plantings. At the KBS site. an additional plot of late
potatoes (referred to as KBS late-2) was planted in an area isolated from earlier
plantings. All plots consisted of 1/4 acre of Caribe' potatoes planted In ca. 30-50 m.
rows. 0.9 m. between rows. 0.26-0.30 m. between plants within a row. CarIbe' Is an
early maturing potato variety with heat and drought tolerance. thus making It suitable
for late plantings when soil temperatures and moisture may be unsuitable for most
potato varieties.

Daily maximum and minimum temperatures were obtained from the standard
weather stations at each site. and degree day accumulations were calculated with a base of
10° C (Logan et al. 1986).

W-

in 1985. In the early planted potatoes In Rhode Island and late planted potatoes at
the Montcalm site. CPB adult and egg mass densities were sampled throughout the
growing season (2 to 3 times per week In Rhode island and once per week at Montcalm).
in late planted potatoes In Rhode island and at the KBS site. densities of egg masses. each
lnstar. and adults were sampled 2 to 3 times per week. in 1986. all lifestages were
sampled 2 to 3 times per week at the KBS and Rhode island sites. and once per week In
Montcalm. In 1987. all lifestages were sampled once per week at all sites. Samples
consisted of nondestructive visual counts of 100-200 plants per plot per sample data.
Harcourt (1964) and Logan (1981) determined 150-200 plants per plot to be optimal
for sampling eggs. larvae and adults of CPB.

in all plots. all predators on potato plants were counted while sampling CPB. in
1987 relative densities of L. grandis adults were sampled at the Rhode Island site with
burlap traps. and absolute densities were sampled at the KBS site with weekly midnight
observation of 100-200 plants per sample data (see manuscript 2).

Daily recruitment of eggs into the plots was monitored throughout the growing
season In the late planted potatoes in Rhode island in 1985. and in all Rhode island and

32

KBS plots In 1986. As the potato plants were beginning to emerge. 100-200 plants
were tagged. and checked every twenty-four hours for new egg masses. All egg masses
were removed daily and tags were switched to new plants every 7 to 10 days throughout
the growing season.

In 1985 and 1986. the egg masses collected in the daily recruitment samples were
subsampied and the number of eggs per mass determined. in plots where daily
recruitment was not measured. the number of eggs per mass was determined from a
subsample of egg masses observed during visual counts of CPB life stages. For each plot.
an analysis of variance was performed to deterrnlne If the size of egg masses varied by
week throughout the growing season.

In 1986. an attempt was made to distinguish the signs of egg mass feeding by
common CPB predators and CPB adults. it was not possible to definitively distinguish
feeding by the mandibulate feeders. L. grandis. C. maculata. and CPB adults. However.
It was possible to distinguish mandibulate feeders from the haustellate feeders. P.
bioculatus and P. maculiventris. The mandibulate feeders generally consumed the entire
egg and only the bottom of the egg chorion where the egg was attached to the leaf
remained. The haustellate feeders pierced the egg with their stylets and sucked out the
contents. leaving the chorion relatively Intact. in 1987 while sampling CPB lifestages.
the densities of CPB egg masses eaten by mandibulate and haustellate feeders were also
sampled In all plots.

In order to estimate the absolute density of preyed egg masses. it was necessary to
determine the length of time that the remains of preyed egg masses are detectable on the
potato leaf (the residence time). in June 1988. a plot of ca. 100 potato plants was ‘
plantad'at the KBS site. The plot was colonized by native CPB adults. and the plants were
checked daily for newly oviposited egg masses. As eggs were oviposited. they were tagged
and rechecked daily for signs of predation. Once an egg mass was preyed on. the type of

feeding was noted. and the egg mass remains were examined daily to determine the point

33

at which they would not be detected in regular sampling of potato plants. The residence
time of preyed egg masses was determined In degree-days (base 10°C) for each feeding
UPO-

Emergence of first (summer) and second generation CPB adults were monitored
with twelve t-m3 screen field cages sat in each plot ca. 150-200 degree-days after the
first observance of the CPB prepupae in the field. Emergence was monitored in early and
late planted potatoes in Rhode Island In 1985-1987. In early and late planted potatoes In
Montcalm in 1986-1987. and in early planted potatoes at KBS In 1986-1987.
(Densities were too low In the late plantings at KBS to effectively sample.) Each cage
was centered over a row of potatoes and contained 3 potato plants. Cages were checked
three times per week for newly emerged CPB adults.

Prepupal and pupal mortality were evaluated in cages In Rhode Island in 1985-
1937 and at KBS in 1986. In 1985 In the Rhode Island late planted potato plot. 3 l-rn3
screen cages were set up in a tilled area of soil just outside the potato field. On three
occasions at 5 d Intervals during the pupation of second generation CPB. 50 prepupae
were collected from the field and released into one of the cages. Emergence of CPB adults
In the cages was monitored every 2-3 days. in 1986 In order to Include the impact of
soil dwelling mortality factors that may be present under the potato canopy (such as L.
grandis larvae) prepupal cages were set up within the potato fields. Prior to the
occurrence of large CPB larvae within a field. 3 m X 3 m plots were marked. and within
these areas all large fourth instar larvae were removed daily. With the occurrence of
prepupae in the field a 1-m3 cage was set up In the center of each of these plots. and 25
prepupae were released per age at 5 day Intervals until 100-125 prepupae had been
released per cage. Cages were checked every 2-3 days for the emergence of CPB adults.
in Rhode island in 1986. three cages per planting were Inoculated with prepupae. At the
KBS site In 1986. and the Rhode island site In 1987. four cages par planting were used.

34

Parasitism by the tachinid. M. doryphorae . was evaluated by sampling CPB
prepupae as they burrowed into the ground to pupate. Collections were made at regular
Intervals throughout the prepupal generation. Collected individuals were placed In
petrl dishes or pint-size containers with moist sand and vermiculite and held in the
laboratory at 20-25°C. Dishes were checked daily for the emergence of CPB or
parasitold adults.

CPB adults and large larvae were sampled to determine the percentage Infected with
B. bassiana . Samples were collected at regular intervals throughout the adult and large
larval generations. Collected individuals were surface sterilized by dipping them in a
1% solution of Zephran Chloride® (Clark 1980). followed by a rinse in distilled water.
insects were then transferred to petri dishes with moist paper toweling and potato
foliage. and the dishes were surrounded with water-saturated paper toweling and held at
20-25°C. Samples were checked every 2-3 days for mortality and/or sporulation of B.
bassiana. at which time the insects were transferred to clean and sterilized dishes with
fresh food. individuals were held for 10 days and if an Individual died. it was held for an
additional two days under high humidity to encourage sporulation of the fungus. When
sampling for B. bassiana Infection or M. doryphorae parasitism. no more than five
percent of the larval or adult population in the field was collected.

WWW

To calculate stage-specific survival rates for a population it Is necessary to
estimate the absolute densities (densities per unit area) of successive life stages. In
populations with overlapping life stages or where all age classes occur simultaneously.
as with the CPB. field estimates at peak density cannot be assumed to reflect the true
density of insects entering or surviving a stage. This is particularly the case when the
development time of successive stages differ. Southwood (1966. 1976). Helgesen and
Haynes (1972). and Lampert and Haynes (1985) described methods for estimating total

35

seasonal incidence in populations with overlapping stages which Involved frequent
sampling of stage-specific densities. When these densities are plotted against
accumulated degree-days. the integration of these Incidence curves divided by the
development time of the stage. estimates the total seasonal production or number of
individuals entering the stage (DENsi). Hence.

DENS; - AREA) / T. i1 l
where:

i - life stage.
AREA; - the Integral of the Incidence curve of stage I. and
T; - the development time of stage I .

Stage-specific survival (83) is then estimated as the proportion of individuals entering
successive stages:

83 . DENS (+1 / DENSI [2]
This method assumes that any mortality experienced In the population occurs at the end
of the stage. thus the residence time of individuals In the field (RTl) equals the
development time of the stage (T I). Sawyer and Haynes (1984) discuss the limitations
of this assumption and present a technique for estimating the true mean residence time
of a stage when mortality is experienced throughout the stage at a constant rate. The
more accurate form of equation [1] Is thus:

DENSI - AREA) I RT. [3]

The technique presented by Sawyer and Haynes uses equations [1] and [2] to

calculate preliminary estimates of stage-specific densities and survival. if. as Is the
case with the CPB. these estimates result In negative mortality (survival estimates >
1.0) either due to sampling error or high mortality experienced early In a stage. their
technique does not yield an appropriate solution. Therefore. to estimate seasonal

densities and stage-specific survival for CPB populations. It was necessary to develop

36

modifications of their technique based on directly measured or estimated recruitment
into successive stages.

Estimation of egg survival (85) when recruitment ls known.
Recruitment into the egg stage was measured directly in all Rhode island and KBS
plantings in 1986. and In the late planting in Rhode island In 1985. Egg recruitment In
the early planting in Rhode Island in 1985 and the early planting In Montcalm In 1986
was estimated with an oviposition model (see Appendix A). and observed adult densities
and temperatures. Using the observed or estimated recruitment (DENSE) and the
observed incidence (AREAE). equation [3] was solved for RTE. With a constant rate of
mortality. Sawyer and Haynes (1984) showed that RT; is related to survival (8.) by the
equation:

FIT] - Ti [(81-1) / In St] [4]
Using T5 - 72 DD base 10°C (calculated from Logan at al. 1985). a unique solution to
equation [4] was found such that (SE-1) I In 85 - RTE I 72.

Estimation of egg survival (85) from density of eggs preyed upon by
predators. In all plantings In 1987. the densities of preyed egg masses were sampled
throughout the season. From these sampled densities. incidence curves for both
haustellate- and mandibulate-preyed eggs were generated by multiplying the egg mass
density by the mean number of eggs per mass. The seasonal densities for preyed eggs
were estimated by dividing the area under each curve by the residence time for that type
of prayed egg. The sum of mandibulate-preyed eggs and haustellate-preyed eggs
(DENSpE) were assumed to represent the number of eggs dying throughout the stage. A
preliminary estimate of total egg density (DENSE') was calculated using equation [1].
with T. - 72 dd. From this. a preliminary estimate of egg survival (85') was calculated
by:

85' - 1 - ( DENSPE I DENSE') [5]

37

Using 85' in equation [4]. a preliminary estimate of the mean residence time of eggs
(RTE') was obtained. my was then used in equation [3] to arrive at an Improved
estimate of total egg density. DENSE". This Improved estimate of total density was used
in equation [5] to calculate an Improved estimate of egg survival. 85". This iterative
process was continued until equations [4] and [5] each converged on final estimates
within 0.0001 35 and RTE.

Estimation of CPB larval survival (83L and S“) when adult
emergence and pupal survival (Sp) are known . For calculating and analyzing
CPB larval and pupal densities and survival. life stages were grouped as follows: small
larvae - 1st and 2nd Instars. large larvae - 3rd and 4th Instars. and pupae - prepupae
and pupae. First instar CPB densities are the most difficult stage to estimate as these
extremely small larvae are difficult to detect on the potato plant once they have
dispersed from the egg mass. Therefore. It was assumed that the incidence of small
larvae was underestimated. and for those plantings where pupal survival and adult
emergence were measured directly. survival of large larvae (8”) was estimated most
accurately by solving backwards (using the method presented by Sawyer and Haynes.
1984) as follows. The number of adults produced per plant (DENSA) was determined by
dividing the mean adult emergence per cage by 3 plants per cage. Survival of pupae (Sp)
was determined directly as the proportion of individuals surviving In the field cages
seeded with prepupae. The density of pupae (or individuals entering stage P. DENSp)
was calculated by:

DENSp - DENSA/ Sp I 6 1
Preliminary estimates of density and survival of large larvae (DENSL' and SLL') were
calculated using equations [1] and [2]. and SLL" was used in the following equation from
Sawyer and Haynes (1984) to calculate an estimate of DENSLL" which corrects for the
difference between RTLL and TLL:

DENSl"-DENSl'[lnS/(S-1)1 [7]

38

The density of small larvae (DENSLs) was calculated by:
DENSLs - SE ‘ DENSE [ 8 l
and survival of small larvae (SL3) was then calculated with equation [2].

Estimation of larval survival (8.3 and 5LL) with corrected estimates
of first instar larval incidence. From the seven plantings where larval survival
was estimated as described above. the error In sampling first instar CPB larval
densities was examined and a predictive model was developed to correct for this error .
it was then possible to estimate total seasonal densities and survival of successive stages
with recruitment estimates generated from the previous stage (as described In the
section on estimation of egg survival when recruitment Is known). However. estimation
of total seasonal density of small CPB larvae was complicated because the mortality rate
is not constant through the stage. but is highest early In the stage. The relationship
between RT. and Si described by Sawyer and Haynes (1984) in equation [4) Is based on a
constant rate of mortality. where:

S(t) - em [91
with:
S(t) - the proportion of the Initial population surviving to time t.
e - the base of the natural logarithms. and
a - a positive constant defining S at time t - 1.
The mean age of the population (p) expressed as a proportion of the maximum life-span
Is defined by the definite Integral:

1
- e'aIdt
ll Io

- -1/a(e'3-1). [10]
Solving equation [9] for a. and substituting Into equation [10]. Sawyer and Haynes
(1984) derive equation [4].

39

For the small larvae of the CPB. where mortality ls highest early In the stage.
equation [9] was replaced with the following which describes an exponential decay in 8
through the stage:

S(t) - e-HIW") (11]
where n is a constant which determines the Initial slope of the curve. For small larvae
of the CPB. n - 2. Again. the Integral of equation [11] is the mean life-span expressed

as the proportion of the maximum life span:

a
1/2
II - I a'3I( )dt
0
- (2/a2) [ -ae'a - e’a +1] [12]
Solving equation [11] for a:
a - -ln$/tI/2. [13]

and substituting this into equation [12] for time t - 1 gives:
er . 2/(In S)2 i S(lnS - 1) + 1 1. [14]

Equation [14] was used to described the relationship between the survival (83])
and mean residence time (RTSL) of small CPB larvae. and larval densities were
estimated as follows. The corrected estimate of first Instar-dd was added to the observed
2nd instar-dd to determine AREASL. The number entering the stage (DENSSL) was
estimated with equation [8]. Equation [3] was then solved for RTSL. and equation [13]
was used to determine SSL. With these estimates of DENSSL and SSL. the density of large
larvae (DENSLL) was determined with equation [8] . equation [3] was then solved for
RTLL. and equation [4] was used to determine SLL- Again. equation [8] was used to
estimate the total production of pupae (DENSp). and survival of pupae (Sp) was
determined using adult emergence (DENSA) and equation [2].

40

This method for estimating stage-specific survival of CPB was used for eight
plantings in which adult emergence. but not pupal survival was measured directly. and
recruitment Into the small larval stage (DENSSL) could be estimated from egg survival.
These included late plantings at KBS in 1986. and 1987. the early planting at KBS in
1987. the early planting at Montcalm In 1986. and the early and late plantings at
Montcalm In 1987.

RESULTS AND DISCUSSION

WWW

Endemic populations of CPB colonized all plantings at the Rhode island and
Montcalm sites in 1985-1987. However. it was necessary to release CPB adults
collected at Montcalm Into the 1985 and early 1986 plantings at KBS. In 1985. from
July 23 to August 8. 2300 CPB adults were released directly into the potato plot at KBS.
in 1986. to Increase the endemic population. 500 CPB adults were released into the
early planted potatoes at KBS between May 25 and mid-June. in 1986 and 1987. CPB
adults collected emerging from the early planted potatoes at KBS were released into the
Isolated late planted potatoes at the same site (KBS late-2). Beetles were released at the
same densities observed in KBS late-1. In 1986. 300 CPB adults were released. and in
1987. 400 adults were released.

Degree-day accumulations for the month of May at the Michigan sites were greater
than those at the Rhode island site for the first half of the month in 1986. and
throughout the month In 1987 (Table 1). Throughout the first and second CPB
generations degree-day accumulations differed only slightly between the sites In 1986.
with the KBS site being a little warmer. Degree-day accumulations were higher at all
sites in 1987. and higher In Michigan than Rhode island. Ail early plantings in 1985-
1987 were colonized by overwintered CPB adults during the last few days of May or the

41

Table 1. Accumulation of degree-days (base 10°C) from May 1. at research sites In
Rhode island and Michigan. 1986-1987.

 

 

 

 

 

Rhode Island KBS. Michigan Montcalm. Michigan

1986 1987 1986 1987 1986 1987

May 1 5 36 40 82 78 78 96
3 0 151 128 154 224 160 227

June 15 274 278 295 419 289 399
3 0 406 419 428 626 413 573

J u iy 1 5 557 594 591 829 559 773
so 726 780 ' see 1035 756 996

Aug 15 900 948 958 1257 907 1196

30 1031 1097 1083 1405 1022 1325

 

42

first few days of June (Figures 1-3) coinciding with plant emergence. Differences in
phenology did exist between sites. however. Daily recruitment samples in 1986.
Indicated that beetles were ovipositing earlier at the KBS site than In Rhode Island
(Figure 4). Although the number of eggs laid In the Rhode island planting far exceeded
that in the KBS site. the initial rate of oviposition was higher at KBS. most likely due to
the warmer early season temperatures.

Dramatic differences in CPB adult colonization and egg recruitment were observed
between early versus late planted potatoes. and within the late plantings. egg
recruitment varied between sites and years. in the late plantings at KBS. egg
recruitment was much lower than that observed in either the 1985 or the 1986 late
plantings In Rhode island (Figure 4). in the KBS site. second generation beetles stopped
ovipositing 20 to 30 days earlier than in the Rhode Island. in Rhode Island. oviposition
ceased at ca. the same Julian day In both years. Adult densities In the Rhode Island 1985
late planting were twice that observed In the 1986 late planting. however. twice as
many eggs were laid In 1986 than 1985. Figures 1 and 4 Indicate that beetles colonized
the planting and oviposited eight to 10 days earlier In 1986 than 1985. Voss et al.
(1988) demonstrated that the magnitude of the second CPB generation In western
Massachusetts was determined by the time of emergence of summer adults. The majority
of adults emerging prior to July 25 oviposited. whereas. those emerging after this date
entered reproductive diapause. It appears that the egg recruitment in late planted
potatoes Is similarly determined by the timing of colonization by summer adults.

The mean number of eggs per mass did differ throughout the season in some
plantings (T able 2). Early and late plantings In Rhode Island generally had smaller egg
masses In the first two weeks that the site was colonized. egg mass size increased
through the oviposition period. and then declined slightly at the end of the generation.
This pattern was also observed in the 1987 early planting at Montcalm. There was no

significant correlation between daily degree-day accumulation and egg mass size.

ADULTS PER PLANT

Figure 1.

43

RHODE ISLAND PLANTINGS

4!

 

 

 

o t W v v 1 1
V I

140 100 180 200 220 240

m- 1986

025‘
C
I
o.m v v v 1 v r t v r v
V I U I

140 100 180 200 220 240

 

 

 

c.75- 1987

 

1
o.m 1 v I v v I ‘ ifim

140 160 180 200 220 240
JULIAN DAY

 

—O—EARLYPLANTNG
—._LATEPLANTING

Densities of adult CPB in potato research plots in Rhode Island. 1985-1987.

44

KBS PLANTINGS

1986

015-

0.50 -

0.25-I

 

000-
140 160 180 200 220 240

0-75- 1987

ADULTS PER PLANT

050‘

025-

0-00 ' ' l ' ' I ' ' I ' ' I
140 160 180 200 220
JULIAN DAY we,
--O-LATE4

 

Figure 2. Densities of adult CPB in potato plots at the KBS site in Michigan.
1986 and 1987.

45

MONT CALM PLANTINGS

2-0 " 1985

1.0-l

 

 

 

0.0 v t V I ' I ' I
140 160 180 200 220 240
1

30‘

1 1986

 

 

 

 

V I V V

- l ' fi
140 160 180 200 220 240

ADULTS PER PLANT

 

 

1

3.0-
1987

q
201
1.0-
o-°"I'—'U"T"Ir'l

140 160 180 200 220 240

JULIAN DAY -—o—EARLY

-—-O-LATE

Figure 3. Densities of adult CPB in potato plots at the Montcalm site In Michigan.
1985 and 1987.

46

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49

Observed egg mass densities were converted to egg densities by multiplying by the mean
eggs per mass for the planting presented in Table 2. The values attained in 1986 were
used in 1987.

The densities of CPB life stages and natural enemies estimated with visual counts at
all the research sites from 1985-1987 are given in Appendix C. The composition of
CPB predator complexes at each site is presented In Table 3. The cocclnellld. C. maculata
was the predominant predator in Rhode Island plantings. and C. maculata and the
phalangid. Phalangium opilio were the prominent predators in Michigan plantings.
Although P. opilio consume CPB eggs and small larvae. there is very little overlap
between their populations in potato fields and that of their CPB prey (Drummond et al.
1988). Therefore. this species was not considered in any further analysis in this study.
Pentatomids were more prominent in Michigan potato plantings than Rhode Island. and as
expected from its reported distribution (McPherson 1982), P. bioculatus was not tound
in Rhode island plantings.

WW

Resldence time oi preyed egg masses. The residence time of haustellate-
preyed egg masses observed in June and July 1988 was 157.77 :l: 12.09 dd (mean i
S.E.). The residence time of mandibulate-preyed egg masses was 83.34 :1: 16.95 dd
(mean :1: S.E.). Because of the small sample available for estimating the residence time
of mandibulate-preyed egg masses (n-2). the mean was compared with that estimated by
Mena (unpublished data). who observed the residence time of preyed CPB egg masses on
native horsenettle. Solanum carolinense L. For 12 mandibulate-preyed egg masses. he
calculated a mean residence time oi 82.81 dd. Thus, for calculating the total seasonal
density of preyed egg masses, the residence times of 158 and 83 dd were used for

haustellate- and mandibulate-preyed egg masses, respectively.

50

 

 

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52

Error in estimates of first lnstar Incidence. Using the data from those
plantings in which first instar CPB densities could be estimated from egg survival and
incidence and survival of large larvae, the errors in estimating first instar incidence
((first instars/plant) x dd) from observed field counts was examined. This error was
found to be inversely related to density. As first instar incidence increased, the error
decreased exponentially. The predicted model used to correct for the error in estimating
first instar incidence is presented in Figure 5.

Total seasonal production and stage-specific survival. Estimates of
total seasonal production and stage-specific survival are presented in Tables 4 and 5. It
was not possible to calculate estimates of total season production and stage-specific
survival in those late plantings where egg recruitment was not sampled directly or
estimated from densities of preyed eggs or the oviposition model. Because the proportion
of adults entering diapause was unknown. it was not possible to use the oviposition model
to simulate egg recruitment in the late plantings.

Again. comparing all plantings. there was a dramatic difference In egg recruitment
between early versus late planted potatoes. With the exception of the 1987 late planting
in Montcalm, egg recruitment in the late planted potatoes was 71 to 92 percent less than
that observed in the early plantings. The late planted potatoes in Montcalm in 1987
differed little from the early planting in recruitment of CPB eggs. This planting was
established while overwintered CPB adults were still abundant, and it's close proximity
to large plantings of early potatoes resulted in a large influx of both overwintered and
summer adults. Boiteau (1986) also found no difference in colonization and egg and
larval densities in delayed plantings of potatoes compared with adjacent early plantings
in New Brunswick. due to the movement of overwintered adults from the early to the late
plantings. In addition, more non-diapausing summer adults may have contributed to the
large CPB population in the 1987 late planting in Montcalm. Warm temperatures
experienced in Michigan in 1987 resulted in early emergence of summer adults and

53

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rd-

 

 

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SONEOIONI
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Table 4. Seasonal production of CPB lifestages in potato plots in Rhode Island and

Michigan in 1985-1987.

54

 

Seasonal Production (mean per plant)

 

 

Small Large

Year Site Planting Eqp larvae larvae Pupae Adults
1 985 Rhode Island early‘ 427.81 35.10
late 50.69 17.13 12.19 10.88 5.22

1986 Rhode Island early 362.83 283.46 43.68 45.02 24.70
late 1 04 .50 24.87 5.99 1.33 0.43

KBS early 68.72 33.88 3.31 3.80 2.63

late-1 20.27 12.61 4.63 0.49 0.13

late-2 2.89 2.89 0.56 0.19 0.00
Montcalm early 213.50 184.29 58.60 109.23

1987 Rhodelsland early 438.96 400.16 76.12 84.12 66.24
late 34.19 32.33 3.63 1 .60 0.27

KBS early 229.73 91.02 20.93 9.17 5.19

late-1 25.11 10.81 1.61 0.00 0.00

late-2 4.57 3.63 0.004 0.00 0.00

Montcalm early 435.84 339.96 30.09

late 386.69 309.35 114.77 37.42 73.86

 

1Larval stages were not sampled.

55

Table 5. Stage-specific survival of CPB in potato research plots in Rhode Island and
Michigan in 19854987.

 

Stage-specific Survival1

 

 

Small Large
Year Site Planting Eggs larvae larvae Pupae Total2
1 985 Rhode Island early .72 .08
late .34 .71 .93 .48 .10
1 9 8 6 Rhode Island early .78 .15 1 .03 .55 .07
late .24 .24 .36 .33 .004
KBS early .49 .11 1.04 .69 .04
late-1 .62 .37 .11 .27 .006
late-2 1.00 .20 .33 .00
Montcalm early .86 .32 1 .00 .-- .51
1987 Rhode Island early .91 .21 1.10 .74 .15
late .95 .10 .58 .17 .008
KBS early .40 .23 .44 .57 .02
late-1 .43 .15 .00
late-2 .80 .001 .00
Montcalm early .78
late .80 .37 .33 1 .97 .19

 

1Methods for calculating stage-specific survival are described in the text.
2Within generation survival: eggs to emerging adults.

56

hence. a larger portion of the population oviposited rather than entering reproductive
diapause. First emergence of summer adults in Michigan in 1987 was 18 days earlier
than that observed in 1986.

Although egg recruitment differed significantly between early and late plantings.
there were not consistent differences in stage-specific survival. Key factor analysis
(Morris 1963, Southwood 1966, 1978) was performed to identify significant trends
and components in within-generation survival. It was necessary to eliminate from the
key-factor analysis those data sets where estimates of stage-specific survival were
incomplete either due to unsampled life-stages, or 100% mortality of the population
before adult emergence. Also. total seasonal production of CPB large larvae and pupae.
and larval and pupal survival estimates calculated for the 1986 and 1987 Montcalm
planting were suspected of being inaccurate. All of these plantings experienced 100%
defoliation prior to completion of the generation. As a result. the later part of the larval
generations in these plots experience 100% mortality due to starvation. This pattern of
mortality is not consistent with the mortality pattern assumed for this analysis and
therefore it cath be assumed to yield accurate results. Also. this extreme situation.
although not unusual in uncontrolled CPB populations in regions with high regional
densities, masks the contributions of other sources of biotic mortality of interest in this
study. For these reasons. the Montcalm data sets were not used in the key-factor

analysis.

W

In this study. identifying mortality factors responsible for long-term trends in
CPB population dynamics was not the objective. Instead, the objective was to identify
those factors responsible for variations in within-generation population survival which

result in varying degrees of plant damage in an agricultural system. For this reason. the

57

following variation of Morris‘s model for population survival (Morris 1963).
presented by Lampert and Haynes (1985) was used:

ch-SE'SSL'SLL‘SP- [15]
To determine which of the components in this model contribute to most of the variation
in Swe. Pearson's bivariate correlation analysis was conducted with stage-specific
survival data from the eight complete data sets available in this study. To obtain a linear
model for examination. the above model was transformed by taking the natural logarithm
of both side. Hence.

lnSWG - Iris; + lnSSL + InSLL + 1081: , [1 6]
Graphical representation of each component of within-generation survival compared
with total survival is presented in Figures 6a-d. The highest degree of curve similarity
existed between total survival and large larval survival and total survival and pupal
survival. The correlation analysis. concurs with this assessment. Correlation
coefficients obtained between total within-generation survival and egg. small larval.
large larval, and pupal survival were .271. .100, .864. and .785 respectively.

Density Dependence. The relationship between stage-specific survival and
density was explored for each component of the model [16]. Density dependence was
tested by plotting the number of individuals entering the stage against the number of
individuals leaving the stage (or entering the successive stage). If the slope obtained
from regression analysis of these data differed significantly from unity. this indicated
that density-dependent mechanisms were operating (Morris 1963. Watt 1964). The
only stage for which survival was density dependent was the pupal stage (Table 6). The
slope of the regression line for pupal survival was significantly greater than unity,
demonstrating that as the density of pupae increased. survival increased.
Pupai Survival. In this and previous studies. the factors responsible for pupal

mortality included: parasitism by the tachinid. M. doryphorae. parasitism by the
carabid larva. L. grandis, and infection by the entomopathogen. B. bassiana. Multble

58

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59

Table 6. Statistics from linear regression analysis testing for density dependence in
survival of immature stages of the CPB. A slope that differs significantly from unity
indicates density dependent mechanisms operating.

 

 

Stage Slope1 95% C.I. F value p
Ems 1.06 1 0.44 34.65 0.001
Small larvae 0.80 1; 0.46 18.14 0.005
Large larvae 1.35 :r. 0.64 26.72 0.002
Ptpae 1.22' 3; 0.19 239.20 0.0001

 

1Values followed by ' indicate significant difference from unity.

6O

regression analysis was performed to detect significant correlations between CPB pupal
survival and M. doryphorae parasitism and B. bassiana infection. Techniques for
detecting parasitism of CPB pupae by the carabid L. grandis were not developed until the
later part of this study, therefore. the significance of L. grandls parasitism could not be
tested.

Parasitism of CPB pupae by M. doryphorae is presented in Table 7. B. bassiana
infection of CPB pupae was not measured directly, however, it was assumed that
mortality of CPB pupae by B. bassiana was directly proportional to that experienced by
CPB adults. The percentage infection of CPB adults and larvae sampled at each research
site are presented in Table 8. Only parasitism by M. doryphorae was significantly
correlated with pupal survival (p - 0.076). The inverse relationship described by the
equation: y - 1.17 - 0.34x, where x - the in (density of M. doryphorae parasitized
pupae). and y - the In (density of emerging adults (surviving pupae». explains 68% of
the variation in surviving pupae (F(1,5) - 10.56, p - 0.023; Figure 7).

M. doryphorae adults iarviposit in the large larvae of the CPB. and the resulting
CPB mortality is generally experienced in the ground-dwelling prepupal stage (Tamaki
et al. 1983). Therefore. to explore the relationship between M. doryphorae parasitism
and host density. the proportion parasitized (arcsin square root transformed) was
regressed on the incidence of large larvae (large larvae x plant‘1 x dd). This analysis
revealed a significant inverse relationship between host incidence and parasitism
(F(1.g)-7.14.p-0.03; Figure 8), indicating an inability of M. doryphorae to respond
to increases in host density. Harcourt (1971) reported the same relationship. and a
relatively constant number of individuals parasitized independent of density. This
resulted in a decline in the proportion parasitized as density increased.

Parasitism by M. doryphorae was higher in the late plantings or second CPB
generation (Table 7). Kelleher (1966) observed the same pattern in Manitoba and

suggested that overwintering mortality limited parasitism in the early season. but

61

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62

Table 8. Beauveria bassiana infection of CPB adults and larvae in potato research plots
in Rhode Island and Michigan, 1985-1987.

 

 

 

 

Larvae Adults
Site Planting n % infected n %lnfected
1.2.8.5
Rhode Island early 500 5.00 350 22.57
late 400 6.00 300 6.67
KBS early
late 6 0.00 7 0.00
Montcalm early 188 0.00 1 84 0.00
late 250 0.40 301 0.33
1.9.8.6
Rhode Island early 550 1.64 400 9.25
late 412 1.27 200 10.50
KBS early 300 0.00 312 0.32
late 175 4.00
Montcalm early 21 8 2.29 41 5 0.24
late 47 0.00 363 0.00
1.9.31
Rhode Island early 1 00 0.00 300 5.67
late 264 0.00 49 2.00
KBS early 117 0.00 205 0.00
late
Montcalm early 1 1 0 0.00
late 1 00 0.00 98 0.00

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65

adults arising from this early generation attacked CPB larvae in the late season. He
suggested that this second generation of parasitolds were often poorly synchronized with
the host papulation. emerging in early August when the host population was rapidly
declining. The relationship between M. doryphorae parasitism and the timing of host
populations in this study was examined in the early and late plantings independently.
Degree-day accumulation prior to the first occurrence of CPB large larvae was
significantly correlated with parasitism In the late plantings (F(1,4)- 27.61. p -
0.006, Figure 9). This relationship was not significant In the early planting
(Fagin-8.61. p-.06. However. a plot of degree-day accumulations at the mid-point in
the large larval generation and M. doryphorae parasitism (Figure 10) indicates that
parasitism increased sharply as hosts were available later in physiological time.
Harcourt (1971) suggests that M. doryphorae parasitism of CPB in Ontario is a late
season phenomena because the parasitoid overwinters In areas south of the province. and
hence is a late arrival each year. These data suggest that M. doryphorae is not well
synchronized with first generation CPB in Rhode island or Michigan. Parasitism was
related to degreeday accumulations suggesting that a temperature dependent process.
such as spring emergence or arrival from southern overwintering sites determines the
timing of M. doryphorae activity in potato fields. In most years In Rhode Island and
Michigan. this lags behind the phenology of the CPB populations for both first and second
generations.

From a pest management perspective. pupal mortality by M. doryphorae has been
of little consequence in managing CPB populations with current production practices.
However. these data suggest that the synchrony between the parasitold and its host. and
hence its impact on CPB mortality. may be enhanced by manipulating the timing of CPB
host through delayed planting of potatoes. Studies of M. doryphorae 's ovenrvinterlng
mechanisms and survival are necessary to determine if potential exists for manipulating

the timing of the parasitoid.

66

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68

Large larval survival. Factors responsible for mortality of CPB large larvae
included predation by L. grandls adults and pentatomids. P. bioculatus and P.
maculiventn’s . infection by B. bassiana . and starvation. Starvation was not a factor in
the data used for this analysis. Methods for sampling L. grandis adults were not
determined until the later part of this study and the influence of this predator was not
evaluated in this analysis.

Percent B. bassiana infection of CPB larvae was difficult to determine from field
samples. as many infected Individuals held in the laboratory died of secondary Infections.
It was Irnposslble to ascertain that the causal agent was 8. bassiana as the fungus did not
sporulate in these cases. Therefore. values for percent infection of CPB larvae given In
Table 8. are conservative. For this analysis. both percentage of larvae infected and
percentage of adults infected with B. bassiana were used as a relative measure of the
impact of the disease on survival of large larvae. These plus the incidence of pentatomid
predators. and parasitism by M. doryphorae were compared with survival of large
larvae with stepwise regression analysis. There was a significant positive correlation
between the Incidence of pentatomid predators and large larval survival. However. when
one of the eleven data points used In this analysis was removed. this relationship was not
significant. and the trend in the relationship was negative. Thus. it Is concluded that
none of the factors monitored were responsible for significant variations in survival of
large larvae.

Early versus late plantings. To examine difference in patterns of CPB
survival between early and late planted potatoes. key factor analysis was repeated on the
early and late plantings separately. Pearson's bivariate correlation analysis was used
to identify significant correlations between components in model [16]. For the early
plantings. correlation coefficients of .968. .025. .759. and .616 were obtained between
total within-generation survival and egg. small larval. large larval. and pupal survival

respectively. For the late plantings. the corresponding correlation coefficients were

69

.167. .705. .792. and .657. Thus. in the early plantings. egg survival rather than
large larval and pupal survival was most highly associated total survival. For the late
plantings. large larval survival was most highly correlated with total within-generation
survival.

Egg survival. Factors responsible for CPB egg mortality Included cannibalism
by CPB adults. and predation by the carabid. L. grandis. the coccinellid. C. maculata. and
the pentatomids. P. macu/iventris and P. bioculatus . Stepwise regression analysis was
performed to examine the relationships between the incidence of each of these mortality
factors. (except L. grandis . and egg survival) for 14 plantings in this study. The
pentatomid species were combined for analysis. No significant correlations were
observed over all plantings. and no significant correlations were observed when early
and late plantings were analyzed independently.

Egg mortality was measured directly in 1987 with observations of the density of
preyed egg masses and the type of feeding damage. in Rhode island. all detectable egg
predation was caused by mandibulate predators (Table 9). In the Michigan plantings.
more eggs were consumed by mandibulate predators in the early plantings. but the
haustellate predators consumed more eggs in the late plantings. Over all plantings. the
proportion of eggs consumed by predators ranged from .05 to .57.

Haustellateopreyed eggs were consumed by pentatomids. the only haustellate
feeders found consistently in potatoes throughout this study. Stepwise regression
analysis was used to identify any significant correlations between the incidence of two
mandibulate feeders. CPB adults and C. maculata . and mandibulate-preyed eggs. A
weakly defined positive correlation was found between CPB adult-dd/plant and the
arcsin square root proportion of mandibulate-preyed eggs (F(1.5) - 6.85 p- 0.05).
Removing one of the seven data points used in this analysis resulted in a slope not

significantly different from zero.

70

Table 9. Predation of CPB egg masses by haustellate and mandibulate predators in potato
research plantings in 1987.

 

Proportion of eggs preyed

 

 

Site Planting Egg density Mandibulate Haustellate
Rhode Island early 438.96 8.84 0.00
late 34.19 5.42 0.00
KBS early 229.73 39.38 17.10
late-1 25.11 14.27 42.68
late-2 4.57 0.00 20.41
Montcalm early 435.84 22.02 0.00
late 386.69 16.23 3.75

 

71

To determine if mandibulate egg predation was density dependent or density
Independent. the natural logarithm of 1 minus the number of mandibulate-preyed eggs
was regressed with the natural logarithm of egg density As the slope of the regression
did not differ significantly from 1.0 (slope t 95% C.I. - 0.951 :t 0.088). it was
concluded to be density independent.

Methods for estimating densities of L. grandis adults were developed in the last
year of this study (see manuscript 2). Weekly density estimates from the 1987 early
plantings in Rhode island and KBS were used to examine the influence of this predator on
CPB egg survival. as well as to gain additional insight into the influence of O. maculata
and CPB adults. Weekly estimates of CPB adult densities. C. maculata densities. and L.
grandis densities. were each regressed independently with weekly estimates of
mandbulatepreyed eggs. Adult CPB densities were expressed as the ratio of adults to
eggs when regressed with the density of mandibulate-preyed eggs to avoid a bias due to
the obvious relationship between adult densities and egg densities. No significant
correlations were found between adult densities and mandibulate-preyed eggs (Fug) -
1.68. p - .23).

Because L. grandis and C. maculata feed on other stages of CPB. to examine the
relationship between the densities of these predators and mandibulate-preyed eggs. the
proportion mandibulate-preyed eggs was weighted by the total prey available for each
predator (multiplied by the density of eggs and small larvae for C. maculata. multiplied
by the density of eggs and total larvae for L. grandis ). This weighting assumes that the
predators do not preferentially feed on one stage over another. This Is the case for L.
grandis (see manuscript 2). and is unknown for C. maculata. C. maculata densities
were not significantly correlated with the weighted proportion of mandibulate-preyed
eggs. either over both sites (Fug) - 0.23. p - .64 ) or in the Rhode Island and KBS
sites independently. The relationship between L. grandis densities and the weighted
proportion of mandibulate-preyed eggs were examined independently for the Rhode

72

Island and KBS site. as L. grandls densities were estimated with different methods. In
both cases. there was a significant relationship between L. grandis densities and the
weighted proportion of mandibulate-preyed eggs (Fug) - 21.13. p - 0.019. and
Fa...) - 14.63. p - 0.019. for Rhode island and KBS respectively; Figure 11).

Harcourt (1971) found egg cannibalism by CPB adults to be the largest source of
mortality of oviposited CPB eggs. In this study. no correlation was found between the
incidence of CPB adults and total CPB egg survival. The significant correlation between
the Incidence of CPB adults and the proportion of mandibulate-preyed eggs in 1987 may
indicate that adult cannibalism was a significant source of egg mortality during this
year. This was a weakly defined relationship. however. and analysis of the data by week
revealed no significant relationship. Harcourt identified cannibailzed eggs by the
remains of the egg mass on the leaf. As stated previously. it is difficult to distinguish
signs of egg predation by the different mandibulate feeders. The remains of an egg mass
preyed upon by L. grandis are Identical to those which Harcourt describes for CPB
adults. Harcourt does not mention predation by L. grandis In his life tables. Given the
nocturnal habits of this predator (see manuscript 2). it may have been overlooked. and
values reported for cannibalism by CPB adults may include L. grandis predation.

As L. grandis densities were not evaluated throughout most of this study. it is
difficult to conclude on its Impact on CPB egg survival. Analysis of 1987 data from the
KBS and Rhode Island early plantings In which L. grandls densities were monitored.
revealed this predator to be the only factor correlated with mandibulate-preyed eggs. it
is possible that L. grandis was responsible for the unexplained sources of variation in
egg and larval mortality over all study sites. That 0.7maculata densities were not
correlated with densities of mandibulate eggs indicates that this predator was not a
significant source of CPB egg mortality In 1987. However. as the feeding preference of
this predator is unknown. this could reflect a preference of this predator for CPB larvae
over eggs. That mandibulate predation of eggs was density independent. suggests that

73

  
    
  

 

 

    

 

 

RHODE ISLAND
2.5-
‘ y- -0.35+4.14x I
r 28 0.88
(z, 1.5-
5 .
O
I.“
I
l 0.5-1
8
I.“ I
-0.5 fi r v I fi I 1 l r I v I
0.1 0.2 0.3 0.4 0.5 0.6 0.7
WEEKLY TOTAL OF DAILY MEAN
L. grandis PER TRAP
KBS
7 .
. y- -2.12+48.48x
. f 28 0.78
z 5
g I
g .
in 3 "
m a
n.
o 1
0 1 -I
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MEAN Lanndls PER PLANT

Figure 11. The relationship between weekly estimates ofLebia grandls densities and
egg predation by mandibulate predators (weighted by the density of total
available prey) in early planted potatoes at the K88. Michigan and Rhode
Island sites in 1987.

74

mandibulate feeders consume a constant proportion of the eggs. Irrespective of egg
density.

Survival of total prey. The relationship between the survival of total suitable
prey and the incidence of the predators was examined for C. maculata and the pentatomid
predators. The incidence of C. maculata was compared with CPB survival through the
small larval stage (SE'SSL). The incidence of pentatomid predators. which feed on all
Immature stages of the CPB. was compared with CPB survival through the large larval
stage (SE‘SSL'SLL). Linear regression analyses for C. maculata and the pentatomid
predators revealed no significant correlations between total prey survival and the
incidence of these predators when tested over all sites and plantings. However. when
Rhode Island and Michigan plantings were analyzed independently. a significant Inverse
relationship between the incidence of C. maculata and survival of its prey was identified
in Rhode island (F(1.3)'41-55v p-0.008; Figure 12). C. maculata Incidence accounted
for 90% of the variability of CPB egg and small larval survival in Rhode island. As
reported in manuscript 3. this predator was well synchronized with both first and
second CPB generations in Rhode Island. but only the first CPB generation In Michigan.

A measure of effectiveness of a predator is its ability to respond to changes In prey
density. The responses of C. maculata and the pentatomid predators to changes in their
prey densities were analyzed by regressing the incidence of each predator with the
incidence of their total prey. C. maculata incidence increased significantly with
increases in their prey (F(1.g)- 25.36. p - 0.0007; Figure 13). There was no
significant correlation between the incidence of pentatomid predators and their prey
(Fug) - 2.94. p -0.12; Figure 14a) when compared over all plantings. Due to the
presence of P. bioculatus . which Is not found in Rhode island. pentatomids were more
abundant in Michigan potatoes. When the incidence of pentatomid predators and their

prey were compared in the Michigan plantings only there was a weakly defined. but
significant correlation (Fa...) - 47.36. p - 0.002. Figure 14b). For the 1986 and

75

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77

a. ALL SITES .

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INCIDENCE OF
PENTATOMID PREDATORS
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INCIDENCE 0F
PENTATOMID PREDATORS

 

 

 

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-2000 2000 6000 10000 14000 18000
INCIDENCE OF TOTAL PREV

Figure 14. The relationship between the incidence (mean per plant x dd) of
pentatomid predators and total CPB prey (eggs. small and large larvae) in
a.) all potato plantings. 1985-1987. and b.) in Michigan potato plantings.
1985-1987.

78

1987 early potato plantings at KBS. P. bioculatus appear to have tracked their prey
densities at about the same proportion of predator to prey (Figure 15a and b).

The sporadic nature of P. bioculatus populations has been noted by several early
observers and has been attributed to variation in overwintering survival by Knight
(1922) who suggests that not more than 5 percent of the overwintering population
usually survives in New York and Minnesota. Jermy (1980) also attributed the failure
to establish this predator in Europe to mortality experienced by the overwintering
population due to cool spring temperature. Thus. It seems evident that this predator
responds to CPB prey densities within a season. but between season the ability of the
predator to respond is limited by abiotic factors determining its density.

This study has demonstrated the importance of two previously unstudied CPB
predators in the within-generation survival of the CPB. The carabid. L. grandis
appears to be responsible for variation in mandibulate-preyed eggs. and densities of the
coccinellid. C. maculata were positively correlated with mortality of CPB eggs and small
larvae in Rhode island. The analysis of key-factors in CPB survival has lead to insights
into the dynamics of these and other CPB natural enemies. However. the fact that the
pentatomids and M. doryphorae do not appear to regulate CPB populations should not be
interpreted that they are insignificant to CPB survival. In 1987 at the KBS site. P.
bioculatus adults were consuming > 110 CPB eggs per day. and reached densities of .34
predators per plant in late June. Tamakl and Butt (1978) determined that extremely
high populations of this predator were necessary to reduce small populations of CPB
below economic thresholds. However. the combined impact of predators was not
‘assessed. At the same time that P. bioculatus densities peaked. L. grandis and C.
maculata adults were consuming up to 100 and 22 eggs per predator per day.
respectively. with densities of .18 L. grandis . and .21 C. maculata per plant. The CPB
population In this planting had a seasonal recruitment of 230 eggs per plant and
experienced 96% mortality before the prepupae left the plants to pupate. The combined

79

 

 

 

 

 

 

 

 

3 "' 2 " 0.02
,. 1986 p.
ll 2
|
I- 2 ~ ,' fpl SI
2 A " c.
< pd é ‘. -o.01
_l ,' ‘1 m
a 1 d I, \ l. m
D: n )5 ‘n D.
I.l.l ‘d
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2
4 " 0.1 E
b - - a-- Total prey
0 " . I ' I ' 0.0 —O-— P. bioculatus
140 165 190 215

JULIAN DAY

Figure 15. Periilus bioculatus and their CPB prey (egg masses 4» total larvae) densities
in early planted potatoes at the KBS site in Michigan. 1986 and 1987.

80

impact of these natural enemies limited the CPB population and plant defoliation below
economic thresholds. it can be speculated that the consecutively mild winters of 1986
and 1987 and the unusually warm spring temperatures in 1987 reduced the
overwintering mortality of CPB predators and enhanced the early season build-up of
predator populations. However. this situation does demonstrate that natural enemies can
control CPB populations. Further studies on factors responsible for regulating natural
enemy populations may identify potential options for manipulating and enhancing
predator densities.

81

Literature Cited

Bethune. C.J.S. 1872. Report of the Entomological Society of Ontario for the year
1871 . Hunter. Rose and 00.. Toronto. 75 pp.

Bolteau. G. 1986. Effect of planting date and plant spacing on field colonization by
Colorado potato beetles. Leptinctarsa decemlineata (Say). In New Brunswick.
Environ. Entomol. 15(2): 311-315.

Casagrande. R.A. 1987. The Colorado potato beetle: 125 years of mismanagement.
Entomol. Soc. Amer. Bull. 33(3): 142-150.

Clark. R.A. 1980. Use of Beauveria bassiana in potato pest management. MS Thesis.
Univ. of Rhode Island. Kingston. RI.

Dover. M.J. and B.A. Croft. 1986. Pesticide resistance and public policy. Bio. Sci.
36:78-85.

Drummond. F.A.. R.L. James. R.A. Casagrande and H. Faubert. 1984. The
development and survival of Podisus macullventrls (Say). a predator of the
Colorado potato beetle (Coleoptera: Chrysomelidae). Environ. Entomol. 13:

1 283-1 28 6 .

Drummond. F.A.. Yok Suheya and E. Groden. 1988. Predation of the Colorado
potato beetle. Leptinotarsa decemlineafa (Say). by Phalanglum opllic (L). J.
Econ. Entomol. (In press).

Forgash. A..I. 1985. Insecticide resistance in the Colorado potato beetle. In: Ferro.
D.N. and R. Hurley Voss (eds). Proceedings of the Symposium on the Colorado
potato beetle. XVII International congress of Entomol. Mass. Agr. Exp. Stn. Res.
Bull. 704. Amherst. MA.

82

Groden. E. and R.A. Casagrande. 1986. Population dynamics of the Colorado potato
beetle. Leptinofarsa decemlineata (Coleoptera: Chrysomelidae). on Solanum
berfhaulfil . J. Econ. Entomol. 79: 91-97.

Harcourt. D.G. 1963. Population dynamics of Leptinotarsa decemlfneata (Say) in
Eastern Ontario. I. Spatial pattern and transformation of field counts. Can.
Entomol. 95: 813-820.

1971. Population dynamics of Lepfinofarsa decemlineata (Say) in Eastern
Ontario. Ill. Maior population processes. Can. Entomol. 103: 1049-1061.

Helgesen. R.G.. and D.L. Haynes. 1972. The within-generation population
dynamics of the cereal leaf beetle. Oulema melancpus (Coleoptera:
Chrysomelidae). a model for age-specific mortality. Can. Entomol. 104: 797-
81 4 .

Jermy. T. 1980. The introduction of Peri/lus bioculatus into Europe to control the
Colorado beetle. EPPO Bull. 10(4): 475-479.

Kelleher. .I.S. 1960. Life history and ecology of Dcryphorophaga doryphorae
(Riley). a tachinid parasite of the Colorado potato beetle. Ph.D. Thesis.
University of Minnesota. 70 pp.

1966. The parasite Dcryphcrcphaga doryphorae (Diptera: Tachinidae) In
relation to populations of the Colorado potato beetle in Manitoba. Ann. Entomol.
Soc. Am. 59:1059-1061.

Knight. H.H. 1923. Studies on the life-history and biology of Perillus bioculatus
Fabricius. including observations on the nature of the colour pattern
(Heteroptera: Pentatomidae). 19th Rep. Minnesota State Entomol. 1921-1922:
50-96.

Lampert. E.P. and D.L. Haynes. 1985. Population dynamics of the cereal leaf
beetle. Oulema melancpus (Coleoptera: Chrysomelidae). at low population
densities. Environ. Entomol. 14(1): 74-79.

83

Lashomb. J.H. and vs. Ng. 1984. Colonization by the Colorado potato beetle.
Leptinofarsa decemlineam (Coleoptera: Chrysomelidae) in rotated and non-
rotated potato fields. Environ. Entomol. 13:1352-1356.

Logan. P.A.. R.A. Casagrande. H.H. Faubert and RA. Drummond. 1985.
Temperature-dependent development and feeding of immature Colorado potato
beetles. Leptinofarsa decem/Ineata (Say) (Coleoptera: Chrysomelidae).
Environ. Entomol. 14:275-283.

McPherson. J.E. 1982. The Pentatomiodea (Hemiptera) of northeastern North
America with emphasis on the fauna of Illinois. Southern Illinois University
Press. Carbondale and Edwardsville. 240 pp.

Morris, F.R. 1963. The dynamics of epidemic spruce budworm populations. Mem.
ent. Soc. Can.. No. 31. 332pp.

Riley. ON. 1869. First annual report on the noxious. beneficial. and other insects of
the state of Missouri. Ellwood Kirby. Jefferson City. MO. 182 pp.

1871. Third annual report on the noxious. beneficial. and other Insects of the
state of Missouri. Horace Wilcos. Jefferson City. MO. 1976 pp.

1872. Fourth annual report of the noxious. beneficial. and other insects of the
state of Missouri. Reagan and Edwards. Jefferson City. MO. 115 pp.

1873. Fifth annual report of the noxious. beneficial. and other insects of the
state of Missouri. Regan and Edwards. Jefferson City. MO.

Sawyer. A. J. and D.L. Haynes. 1984. On the nature of errors involved In
estimating stage-specific survival rates by Southwood's method for a population
with overlapping stages. Res. Pop. Ecol. 26: 331-351.

Tamakl. G.. R.L. Cheuvin and A.l(. Burdltt. Jr. 1983. Field evaluation of
Dcryphomphaga doryphorae (Diptera: Tachinidae). a parasite. and Its host the
Colorado potato beetle (Coleoptera: Chrysomelidae). Environ. Entomol. 12(2):
386-389.

84

Tamakl. G. and B.A. Butt. 1978. impact of Peril/us bioculatus on the Colorado
potato beetle and plant damage. Tech. Bull. USDA No. 1581. 11 pp.

Voss. R.H.. D.N. Ferro and J.A. Logan. 1988. Role of reproductive diapause in
the papuiation dynamics of the Colorado potato beetle (Coleoptera:
Chrysomelidae) in Western Massachusetts. Environ. Entomol. 17(5): 863-871.

Walsh. DD 1865. The new potato bug and its natural history. The Practical
Entomol. 1: 1-4.

Watt. B.A. and R.A. LeBrun. 1984. Soil effects of Beauveria bassiana on pupal
populations of the Colorado potato beetle (Coleoptera: Chrysomelidae). Environ.
Entomol. 13: 15-18.

Watt. K.E.F. 1964. Density dependence in population fluctuations. Can. Entomol.
96: 1147-1148.

Wright. R.J. 1984. Evaluation of crop rotation for control of the Colorado potato
beetle (Coleoptera: Chrysomelidae) In commercial potato fields on Long Island. J.
Econ. Entomol. 77: 1254-1259.

MANUSCRIPT 2.

Biology and Seasonal Dynamics of Lebia grandls Hentz (Coleoptera:
Carabldae). Predator and Parasitold of the Colorado Potato Beetle.

(Coleoptera: Chrysomelidae)

ABSTRACT - The biology and seasonal dynamics of the carabid beetle Lebia grandls
Hentz were investigated in Rhode island and Michigan. and its potential impact on
Colorado potato beetle (CPB). Leptinctarsa decemlineata (Say) populations was
evaluated. L. grandis fed on all Immature stages of the CPB. and was found to feed over a
wide range of temperatures. This predator appeared to be quite specific to the CPB. only
feeding on aphids when CPB prey were absent. L. grandis consumed more CPB per day
titan the five other endemic natural enemies studied to date. Field cage studies
demonstrated the potential for L. grandis adults to reduce CPB populations and showed a
strong density dependent response by this predator. L. grandis was found to be

primarily nocturnal. with peak activity between 9 pm and 2 am. A burlap trap was
designed which increased detection of this predator during daylight hours. Seasonal
activity patterns were determined in the field. and In combination with laboratory
development studies. indicated that this species completes one generation per year in RI.
and Mich.

L grandis larvae are ectoparasitoids of CPB prepupae and a sampling technique of
tethering hosts was developed which revealed the pupation site of the host without
dislodging the parasitolds. In 1986 13.5% (n - 200) of tethered hosts released at the
Mich. research site were parasitized. in 1987 weekly parasitism levels were
determined at this site. and parasitism reached >50%. In R.l. In 1987. parasitism of
tethered CPB was barely detectable. although production of summer adult L. grandis was

evident from trap catches.
8 5

86

INTRODUCTION

The foliar searching carabid. Lebia grandis Hentz. was first reported as a predator
of the Colorado potato beetle (CPB). Leptinotarsa decemlineata (Say) by Riley (1871).
in 1936 French entomologists collected L. grandis along with other CPB natural enemies
In New York to study their potential for controlling the CPB In Europe (Bruneteau
1937). Chamboussou (1938. 1939) described the biology of L. grandls and succeeded
In mass rearing the predator on the CPB. The life cycle of the genus Lebia is unusual.
The adults are predaceous on eggs and larvae of chrysomelids. and the larvae are solitary
ectoparasitoids killing pupae of the same hosts (Madge 1967).

No reports of field releases of L. grandis have been published. although
Chamboussou (1938. 1939) suggested that It had tremendous potential for biological
control of the CPB. We have found L. grandis to be one of the more common egg
predators in potato research fields in R.l.. Madge (1967) reported it widely distributed
throughout the Eastern half of the U.S. north of Mexico. No research concemlng L.
grandis has been published since Chamboussou (1939). making this species the least
studied of the common CPB endemic natural enemies. in this study we investigated the
life history and seasonal dynamics of L. grandis in potatoes In RI. and Mich. as part of a
larger study evaluating natural mortality of the CPB in the northeast and northcentral

813188.

MATERIALS AND METHODS
Research was conducted at the University of Rhode Island and Michigan State
University. Field studies In R.l. were conducted in 0.1 ha potato plots at the University
of Rhode Island Research Farm. Kingston. RI. In Mich., field studies were conducted in
0.1 ha potato plots at the Michigan State University Kellogg Biological Station (KBS) in
Hickory Corners. Mich. The incidence of L. grandis was also monitored at the MSU
Potato Research Farm In Stanton. Mich.

87

Consumption rates and prey specificity. In August 1985 and 1986. L.
grandls adults were collected in potato plots in R.i. and Mich. to determine their daily
consumption of immature CPB. Predators were sexed and held individually In petri
dishes with moist paper toweling and prey in excess of their daily consumption.
Predators were given CPB eggs. first. second. third. or fourth instars. and held for 7
days in growth chambers set at 25°C and 16:8 (L:D) photoperlod. Five adult L. grandls
were tested per prey type. Consumption was determined and new prey were added at 24
h intervals. To determine how temperature influenced L. grandls feeding. CPB egg
consumption was monitored In growth chambers at constant temperatures of 15. 20.
25. and 30°C (11°C) for five days (10 predators were tested at each temperature).
Predators were handled as described above and consumption checked daily. Analysis of
variance (SAS Institute 1985) was conducted to determine if predation varied
significantly with temperature. An analysis of covariance (SAS Institute 1985) with
temperature as the covariate was conducted to determine if daily consumption rates
varied significantly over the duration of the study. The class variable was day.

A choice test was performed. to determine If L. grandis adults preferentially feed
on CPB eggs or larvae. Five predators were held Individually in petri dishes with moist
paper toweling and fed 10-50 CPB eggs plus 5-10 first and 510 second Instars every
day. Consumption was recorded and new prey were added every 24 h for a period of five
days. The difference between the starting and finishing proportions of each prey type
was calculated. and It was assumed to be significant if the 95% confidence Intervals
about the difference did not overlap with zero.

To determine L. grandis prey specificity. adults were provided with three
alternate prey commonly found in the Mich. study area. The prey tested included the eggs
and larvae of both the coccinellid. Epilachna varivestis Mulsant. collected from bush
beans and the chrysomelid. Lama trilineata (Oliv.). collected from wild solanaceous
plants. We also tested the potato aphid. Macrcslphum euphorbiae (Thomas). collected

88

from greenhouse grown potatoes. Adult predators were held individually in petri dishes
with moist paper toweling and one type of prey for 2 or 3 days. In the E. varlvesfis
test. eight predators were set up with either 30 to 55 eggs or four small larvae per
dish. in the L. trilineata test. 13 predators were set up with 10 to 35 eggs or 6 to 34
small larvae. After three days the L. trllineata were replaced with three third Instar
CPB. For the aphid test. each of five predators was provided with 25 aphids per day. and
five control dishes were set up without predators to monitor the survival or
reproduction of the 25 aphids placed in each dish. On the fourth day. the aphids were
replaced with a combination of 25 aphids and seven CPB second and third instars. All
tests were examined daily and missing prey were replaced at Initial densities.‘

Cage studies. To determine the impact of L. grandis adults on CPB mortality.
field cage studies were conducted in R.I. in August, 1986. Six screen walk-In cages (3.6
x 1.8 x 1.8 m) were erected In a newly tilled field. Into each cage two rows of 10
greenhouse grown potato plants were transplanted. Potato stems Infested with CPB egg
masses were collected from nearby plots. and placed in 6-inch pyrex test tubes with
water. The tops of the tubes were sealed with parafiim. and the bouquets were set
within the cages. Test tubes were sunk into the soil and the CPB-infested stems stood
within the stems of the transplanted plants where they were secured with wire to
existing stems. CPB egg densities in the cages were set at 500 eggs per cage in 3 cages.
and 250 eggs per cage in 3 cages. At each of these prey densities. L. grandls adults were
Introduced at densities of o. 10 and 15 predators per cage. All CPB eggs and larvae
within each cage were counted every 3 to 4 days over a three week period. The data were
pooled for all predator cages to examine the relationship between prey density and
consumption rates. Consumption per predator per day over the interval was regressed
on available prey at the beginning of each sampling interval.

Temperature-dependent development. L. grandis eggs adhere to soil
particles and adult females proved reluctant to oviposit on other substrates. Thus to

89

determine egg development rates. mating pairs of L. grandis adults were held in 10 cm
petri dishes with moist sand and vermiculite in growth chambers held at constant
temperatures of 20. 20.5. 23. 25. 26. and 30°C u. 1°C) with a photoperiod of 16:8
(L:D). The adults were removed daily and transferred to identical dishes. After the
adults were removed. the dishes were incubated at the same temperatures and monitored
daily for newly-hatched L. grandis larvae.

The development rate for the parasitic and pupal stage of L. grandis was
determined using CPB prepupae harvested from laboratory cultures or collected from
field plots as they began to burrow Into the soil. The prepupae were introduced
individually into 2 oz. plastic Solo ‘3’ cups with moist sand and vermiculite and allowed
to burrow. Within 30 min. of introducing the prepupa. one L. grandls first Instar was
added to each cup. The cups were sealed to retain moisture and placed in growth
chambers at constant temperatures of 17. 20. 23. 26. and 29°C (11°C). The dishes
were checked regularly for emergence of CPB or L. grandls adults. The minimum
standard error method (Casagrande 1971) was used to determine the best predictive
thresholds for egg and larval and pupal development. Percent development per day was
regressed on temperature to determine the appropriateness of a linear model over the
range of temperatures tested.

Thirty-five CPB prepupae were parasitized by L. grandis first instars and held at
variable ambient temperatures in a field laboratory at KBS. Emergence of adult CPB and
L. grandis was monitored daily. Temperatures were recorded continuoust throughout
the development period and the degree-day accumulation at emergence was compared
with that predicted from the model developed from the constant temperature studies.

Dally activity patterns of L. grandls adults. Chamboussou (1939)
reported L. grandls to be primarily nocturnal. in order to optimize sampling periods.
the daily activity patterns of adult L. grandis were determined in potato plots at the K88
research site in 1988. On three separate occasions in June and July. 100 CPB Infested

90

plants were sampled visually every 30 min. over a 24 h period. During the night.
flashlights were used to illuminate plants. Care was taken to avoid illuminating plants
except for the moments during which a plant was sampled. in 1987. the 24 h study was
repeated at the KBS site on June 22. One hundred and fifty plants were randomly
sampled once every two hours between 9 pm and 3 am. and once every three hours
between 3 am and 9 pm. in 1987. similar observations were made in potato plots in
R.I. On July 1. 150 randomly selected plants were sampled at 1 am. 6 am. 10 am. 3
pm. 7 pm. and 10 pm. On this date. after a plant was sampled visually. soil In ca. a 15
cm radius surrounding the plant was examined to a depth of ca. 4 cm to uncover any L.
grandis in the soil.

Seasonal variation In prey consumption and oviposition. In 1987. 3 to
40 (ave. 11) L. grandis adults were collected weekly from potato plots In R.I. and Mich.
to determine seasonal variation in prey consumption and oviposition. Predators were
sexed and held in petri dishes with moist sand and verrnicuiite and 1-3 CPB egg masses
(ca. 80-100 eggs). After 24 h predators were removed and released. and the number of
eggs consumed was recorded. Dishes which had contained female predators were then
incubated at 23 to 25°C until L. grandis eggs hatched and first Instar L. grandis were
counted. allowing calculation of the proportion of females ovipositing on the day of
capture. A two-way analysis of variance was performed to determine If consumption
rates varied by sex and month. Data were pooled by month for June. July. and August
with n - 36. 13. and 65 for males. and n - 28 . 20. and 66 for females. Ninety-five %
C.I. about the means were compared to detect significant differences between treatment
combinations.

Seasonal Incidence. in 1985. 1986. and 1987. densities of L. grandis adults
and CPB eggs and larvae were monitored In potato plots in R.i. and Mich. Plots in R.I.
included both an early and isolated late planting of potatoes in all three years. plots in
Michigan included early and late plantings at the MSU potato research farm In Montcalm

91

Co.. Mich. (a commercial potato growing region) In 1986 and 1987. and a late planting
in 1985. Also. both early and late planted potato plots were monitored at the KBS site in
Mich. At this site. plots included a late planting In 1985. and an early and an adjacent
late planting in 1986 and 1987. Early plots were planted in late April and early May at
all sites. and late plots were planted In late June in Mich.. and early July In R.I. The fast
maturing variety. Caribe'. was used in all plots in this study. and with the exception of
the Montcalm Co. site. no pesticides were applied to any plots. In Montcalm. herbicides
and fungicides were used. as well as an insecticide (Imldan) for CPB in the early
planting in 1987.

Visual counts of L. grandis adults and CPB life stages on plants were conducted two
to three times per week in 1985 and 1986. and once per week in 1987. One hundred to
150 whole plants were sampled per sample date.

in 1986. It was observed that L. grandls adults aggregated during the day in rolls
of burlap laid on the top of 1 m3 field cages In potato plots. in 1987 a trap was designed
using a 20 by 45 cm strip of burlap loosely wrapped and tied around a 40 cm wooden
stake. Traps were set within the foliage of 12 to 50 potato plants In plots in R.i. and
Mich. in 1987 (Figure 1).

In 1987. night observations were also made in potato plots at the KBS site in
Mich.. to determine the seasonal incidence of L. grandis. Once per week. 100 potato
plants were sampled with flashlights between midnight and 1 am. and L. grandls adults
on the plants or on the surrounding soil (within a 15 cm radius around the plant) were
counted. Adults were collected and held to determine whether they oviposited (as
previously described).

L. grandls first Instar longevity. To determine the potential searching time
for parasitic L. grandis larvae. their longevity was determined in the absence of hosts.
Groups often newly hatched first instar L. grandis were placed In petri dishes with
moist soil and held at 25°C in growth chambers. Surviving L. grandis larvae were

92

Figure 1. Burlap trap used for sampling Lebia grandis.

93

 

94

counted daily. Survival was compared in two soil types: a 50:50 sterilized sand and fine
vennlculite mix (10 replicates) and a nonsteriiized sandy loam from the Montcalm
potato research field (6 replicates). Linear regression (SAS Institute 1985) was used
to compare differences In mortality between soil types. The arc sins of cumulative.
mortality was regressed on days raised to the 2"9 power.

L. grandls parasitism. Sitting soil for L. grandis parasitized CPB prepupae
proved ineffective since it dislodged the ectoparasitoids from their host. making
recovery difficult. in 1986. CPB prepupae were successfully tethered with standard
polyester sewing thread. A noose made on a 20 cm long thread was slipped around a CPB
prepupa behind the prothoracic shield and legs. Tethered prepupae were attached to a
marker and released in potato plots where they burrowed into the soil and pupated
(Figure 2a.b). Five to seven days following release. the thread was carefully uncovered
revealing the pupatlon site of the CPB and if parasitized. the L. grandls larva lying
adjacent to its host (Figure 20).

In 1986. a total of 281 field collected CPB prepupae were tethered and released at
the KBS site. July 5 - August 21. On July 15. the mortality of tethered prepupae was
compared with that of nontethered prepupae. Forty nontethered prepupae were released
into the research field and covered with a 6 oz. paper cup to restrict their area for
burrowing. At the same time. 40 tethered CPB prepupae were released. Four hours
later. the prepupae were checked to assure successful burrowing. and the paper cups
were removed and the burrowing site of the nontethered prepupae was marked. The CPB
prepupae were recovered eight days later and the depth of pupation was measured.

in 1987. at the KBS site 60 to 100 prepupae were collected. tethered. and
released per week from mid June to late August. in 1987 in R.I.. 108 tethered prepupae
were released in the early planting on June 30. and 100 were released In the late
planting on July 19. Both releases coincided with peak CPB pupation at the sites. In

addition. two releases of tethered prepupae were made in a small plot of nonrotated

95

Figure 2a. Tethered CPB prepupa. b. Tethered prepupa burrowing into the soil.
and c. Parasitized CPB prepupa with adjacent Lebia grandis larva.

£6

 

97

potatoes in R.I. during peak pupation of first generation CPB. Twenty tethered prepupae
were released on June 30. and 80 were released on July 7.

All released prepupae were recovered 5 to 7 days after release. and L. grandls
parasitism and pupal mortality was recorded. Those unrecovered tethered CPB. and
those parasitized as larvae by tachinids were deleted from the total when calculating
percent mortality and L. grandis parasitism. The density of CPB prepupae in the soil
was not sampled directly In the potato plots. thus fourth instar larval densities were
used to examine the synchrony of L. grandis parasitism with CPB prepupal densities.
The CPB fourth instar incidence curves were advanced 76 DD representing the

development time for CPB fourth instars.

RESULTS

Consumption rates and prey specificity. L. grandls adults fed on all
immature stages of the CPB (Table 1). Daily consumption of CPB eggs followed a
significant quadratic trend between 15° and 30°C (F1397 - 114.39. P - 0.0001).
with consumption rates doubling between 15° to 20°C. Egg consumption per individual
over all temperatures was significantly less on day 1 of the study. apparently due to the
disturbance of collecting and setting up the experiment. Egg consumption during the
remaining 4 days of the experiment did not change significantly. L. grandis did not
demonstrate any preference for prey type when fed a combination of CPB eggs and first

and second instar larvae. There was no significant difference In the Initial and finishing
proportions of each prey type (mean 1 SE. difference for eggs. first and second instars

was -0.03 x 0.03. -0.02 3, 0.02. and 0.05 1», 0.03. respectively).
Only two of the eight predators fed E. varfvestr‘s eggs and small larvae over two
days consumed any prey (mean 3, SE eggs consumed - 0.38 .+_ 0.26; mean larvae

consumed - 0.0). Only four of the 13 individuals provided with L. frilineafa eggs and
first Instars consumed any prey (mean :2 SE. eggs consumed - 0.04 .1; 0.04; mean 3 SE

98

Table 1. Lebia grandis consumption of Immature stages of the CPB.

 

 

Consumed per day
CPB stage N Temperature (mean a», S.E)
Eggs 1o 25 47.38 i 2.071
151 instars 5 25 17.76 1 1.14
2nd instars 5 2 5 6.75 3, 0.59
3rd instars 5 2 5 2.52 1; 0.27
4th instars 5 25 1.32 .+_ 0.13
Ems 1 0 1 5 20.90 1; 1.45
Ems 1 0 2 0 44.00 1. 1.50
Eggs 10 25 47.38 1 2.071
5GB 1 0 30 41.92 a; 2.35

 

1Data from the same experiment.

99

larvae consumed - 2.11 :t 1.24). All 13 predators consumed prey when fed three CPB
third instars on the fourth day (mean 1, SE - 2.31 1, 0.71).

In the aphid consumption test. dishes with predators had fewer aphids than the
controls on day two when L. grandis consumed 7.6 1; 1.50 aphids and on day three when
they consumed 12.2 .t 4.12 (mean t SE) aphids. L. grandis did not consume aphids on
the first day they were given this prey. or on the fourth day when they were given
aphids in combination with CPB larvae. With the combination of prey types. they did
consume 5.6 .+_ 0.68 (mean 1, SE) CPB larvae.

Cages studies. Field cage studies demonstrated the ability of L. grandls to
control low to moderate CPB populations (0.4 to 0.75 egg masses per plant) with
predator densities of 0.5 to 0.75 per plant (Figure 3). in three of the four predator
cages. L. grandis consumed all available prey within 10 days (prior to the prey cohorts
completing the third stadium). CPB survival In the control cages averaged 38% through
the larval stages. In this study. the consumption rate per predator per day increased
with the number of available prey (Figure 4). demonstrating a strong positive density
dependent response.

Temperature-dependent development. The best predictive threshold for L.
grandis egg development was 10.5°C (Figure 5a). Eggs required 129 DD. base 10.5°C.
to complete development. or 8.82 .+_ 0.56 days at 25°C. Egg development was highly
correlated with temperature over the range of temperatures tested (Figure 5b).

The best predictive threshold for L. grandis larval and pupal development was
11.25°C (Figure 6a). The parasitolds required 368 DD base 11.25°C to complete
development or 24.89 31.35 days at 26°C. Again. parasitoid development was highly
correlated with temperature over the range tested (Figure 6b).

L. grandis parasitolds developing at variable ambient temperatures in the field
laboratory required 384 1; 5.2 00 base 11.25°C to complete development. or 28 g 0.2

100

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THRESHOLD TEMPERATURE (°C)

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Figure 5. a.) Results of substituting different thresholds for Lebia grandls egg

development data. and b.) Lebia grandis egg development as a function of
temperature.

103

 

 

 

 

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Figure 6. a.) Results of substituting different thresholds for Lebia grandis larval

and pupal development data. and b.) we Miami and pupal development
as a function of temperature.

104

days. The mean observed emergence occurred within one day of the predicted 27 days or
368 DD base 11.25°C.

Dally activity patterns of L. grandls adults. In 1986 a total of 18 L.
grandls adults were observed between 6 pm and 10 am on the three sample dates. and
12 of these individuals (67%) were observed between 11:30 pm and 2 am. in 1987
110 L. grandis adults were observed over the 24 h study period. Peak adult activity
(mean-0.10 per plant) occurred between 9 pm and 2 am. with 37 percent of all
sightings occurring within this period. At this higher density. adults were observed
during each sampling interval with the lowest densities (mean- 0.04 per plant) at 3
pm.

In R.i. in 1987. seven L. grandls adults were observed on the plant foliage during
the 24 h study period. Five of these seven were observed at 10 pm. An additional 35 L.
grandis were found on or In the soil at the base of the plants. At 10 pm 63 percent of
the observed L. grandls were on the foliage. however at all other sample times. 020
percent were on the foliage.

Seasonal variation in prey consumption and oviposition. Analysis of

variance of prey consumption revealed a significant difference in consumption by month
(F1324 - 28.49. P - 0.0001) and sex (H.224 - 11.60. P- 0.001), and a significant

Interaction between these variables (F1224 - 7.80. P - 0.006). Prey consumption by
females did not change significantly through time. averaging 43.68 3 1.25 ( mean 1;
SE) eggs per day. Males consumed significantly fewer eggs per day (mean 1; SE - 23.97
1 2.20) than females In June. However. their consumption increased throughout the
summer (Figure 7). and by August was not significantly different from females.

Two female L. grandls were collected on May 31 (328 00 base 10°C from April 1)
In Mich.. and one oviposited within one day after collection. Oviposition peaked in mid
June. with 88% of the 15 females collected between June 12 and 19 ovipositing. A
second peak in oviposition was observed between July 14 and 22 with 4 of the 5

105

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Individuals collected ovipositing. Of the 11 females collected In July 27. only three
(27%) were ovipositing. and no ovipositing females were collected after this date.

In R.i. the first female L. grandls were collected on June 2. but oviposition was not
observed until June 16 (327 DD base 10°C from April 1). Oviposition in R.i. peaked
between July 1 and July 16. with 73% of the 15 females collected over this time period
ovipositing. None of the 83 females collected between July 17 and August 19 oviposited.
There was no difference in fecundity between R.i. and Mich. L. grandls. Females laid
15.47 g, 1.85 (mean 1; SE) eggs per day.

Seasonal incidence. L. grandls was observed at all sites sampled in all years
(T able 2 and 3). The adult predators were observed more frequently in early potato
plantings than in the late plantings. although they were sighted as late as September.
There was generally no correlation between the seasonal density of CPB eggs and the L.
grandls densities in the sampled plots.

The 1987 trap catches from the Ml-KBS site are plotted with the L. grandls
densities observed during both the midnight and daytime predator counts at this site in
Figure 8. The burlap trap catches gave a fairly good representation of the changes in
predator densities observed at night. Daytime counts of this predator were generally
considerably less than night counts. and did not indicate the seasonal change In density
that the other sample methods showed.

The midnight observations of L. grandis and the densities of the Immature stages of
the CPB are plotted in Figure 9 a.b. The first predators were observed on May 29.
coinciding with the Initiation of CPB oviposition. L. grandls densities peaked in mid
June. coinciding with the peak in CPB larval densities. Based upon soil temperatures
and the first observance of L. grandls oviposition. the predicted first emergence of new
adults of L. grandis at the KBS site was on July 19. and the predicted peak emergence
was on July 30. No adult L. grandis were trapped or sampled at this site after August
1 0 .

107

 

 

 

 

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L. grandls

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JULY. 26 AUG 28

Figure 9. a.) Densities of CPB stages In Michigan potato plots in 1987. and
b.) densities of Leia grandls adults in Michigan potato plots In 1987
(from midnight observations).

111

The 1987 burlap trap catches of predators and densities of the Immature stages of
the CPB at the R.i. site are plotted in Figure 10 a.b. In R.i.. the first predator was
trapped on June 1. coinciding with the first occurrence of CPB eggs. Trap catches peaked
in late June. coinciding with the peak In CPB larval densities. A large second peak in L.
grandis trap catches was observed in early July. but none of these later individuals
oviposited. No adult L. grandis were trapped after August 18 at this site.

L. grandls first instar longevity. There was no difference In mortality rate
of L. grandis first Instars in the two soil types tested (95% confidence Intervals for the
slopes and y-intercepts completely overlapped). The mean longevity of first Instar L.
grandis at 25°C without hosts was 4.07 1 0.14 days.

L. grandls parasitism. Of the 200 tethered prepupae recovered at the KBS
research site in Mich. In 1986. 13.5% were parasitized by L. grandis larvae.
Parasitism peaked between July 9 and 20. with 29% of the tethered prepupae released
on July 9 parasitized over this time period (Figure 11). This peak in parasitism
coincided with peak CPB prepupal densities in the research plot . Mortality due to
predation and other factors was fairly constant throughout the summer. There was no
difference in mortality or L. grandis parasitism between tethered and nontethered CPB
prepupae. Total mortality for nontethered CPB was 35.5% (n-31) versus 34.4%
(n-32) for tethered CPB. In both cases. only two Individuals were parasitized by L.
grandis. There was no significant difference in the depth of pupation between tethered
and nontethered CPB ( mean 1 SE - 2.96 1 0.19 cm and 3.09 1 0.30 cm. respectively).

in 1987. L. grandis parasitism of tethered prepupae was detected from June 15
through August 20 (Figure 12). During peak CPB prepupal densities in the research
field. parasitism exceeded 50%. From observed soil temperatures and L. grandls
oviposition. the predicted first hatch of L. grandis eggs occurred ca. three to five days
prior to the presence of CPB prepupae. and continued through August. As indicated by

the parasitism of the tethered prepupae. L. grandis larvae were present and active

112

 

 

 

 

 

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Figure 10. a.) Densities of CPB stages in Rhode island potato plots In 1987. and
b.) trap catches (mean per trap per day) of Lebia grandis adults In Rhode
island potato plots in 1987.

113

   

 

 

 

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Figure 11. Parasitism rate of tethered CPB prepupae and density of CPB prepupae
in Michigan plot in 1986

114

 

 

 

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Figure 12. Parasitism rate of tethered CPB prepupae and density of CPB prepupae
in Michigan plot in 1987.

115

throughout most of the growing season. even when hosts were at very low densities or
absent. Again. percent mortality of prepupae due to factors other than L. grandis was
fairly constant throughout the season.

Of the 102 tethered CPB recovered from the early planting in R.i. In 1987. 86%
were healthy. 2.9% were Infected with Beauveria bassiana . less than 1% were eaten.
and 9.8% died due to unknown causes. No L. grandis parasitism was detected. Of the
100 tethered larvae released In the late planting at R.i.. most (52.7%) were
unsuccessful in burrowing. and no L. grandis parasitism was detected. Seventeen of the
108 tethered prepupae released in the nonrotated field In R.i. on June 30 were
recovered. and 29.4% (5 Individuals) were parasitized by L. grandis . 58.8% (10)
were healthy. and the remainder (2) died due to unknown causes. Of the 74 tethered
CPB recovered from the July 7 release of 80 tethered prepupae 6.8% were parasitized.
6.8% were Infected with B. bassiana . 1.4% were eaten. 78.4% were healthy. and 9.5%

died due to unknown causes.

DISCUSSION

Although L. grandis has been almost entirely overlooked for the past 50 years. it
may be the most significant predator of the CPB in R.i. and Mich. This predator is
primarily active at night and our sampling indicates that only a very small percentage of
the L. grandls adUIts can be found during the day. Pitfall traps seldom catch these
foliar-searching carablds which tend to move from one plant to another without
contacting the soil. When disturbed. individuals drop to and crawl into the soil rather
then run across it. Predation by L. grandls is difficult to distinguish from that of other
mandibulate predators. particularly cannibalism by the CPB adults. The parasitic
larval stage of L. grandis is easily dislodged from CPB pupae and Is not readily apparent
In the soil. Ari these behavioral features tend to mask the significance of L. grandis.

116

The burlap trap catches tracked the dynamics of L. grandis populations as observed
with night observations. Population peaks indicated by the trap catches and the night
observations were consistent with the peaks observed In the parasitism levels. Both
burlap traps and nighttime counts appear superior to daytime counts. but these methods
are also affected by weather conditions as both are positively influenced by high
humidity and rainfall.

I in laboratory studies. L. grandls consumed more CPB prey per day than any other
predator studied to date (Table 4). Although it demonstrated no preference for any
particular prey stage in choice tests. its largest impact is probably on the egg stage. L.
grandis consumed more eggs than larvae before it was satiated. and when encountering
an egg mass. It generally consumed all or most of the eggs in the mass. This Is consistent
with studies of CPB population dynamics which report that the highest mortality occurs
In the egg stage (Harcourt 1971. Groden and Casagrande 1986). This was also evident
In the cage studies with L. grandis where it continued impact on the larval populations
was also evident.

The CPB emerges in late April and early May in R.I. and Mich. and oviposition is
Initiated in late May and early June. The CPB is well adapted for development at the cool
temperatures experienced at this time of the year (Logan et al. 1985). however these
cool temperatures have been a major limitation for endemic (Drummond et al. 1984)
and Imported (Obrycki et al. 1985. Drummond et al. 1987) natural enemies. L.
grandis' predation activity at relatively low temperatures (less than 20°C) enhances
Its potential for control of this early season pest.

Thus far. L. grandis appears to be very specific to the CPD. not even feeding on
other solanaceous feeding Chrysomelids. Although in the absence of CPB prey. L. grandis
did consume aphids. It did not eat aphids in the presence of CPB. This specificity is
advantageous with a life cycle so closely linked to that of Its prey. From a management
perspective. the fact that L. grandis will consume aphids in the absence of its preferred

117

Table 4. Consumption of CPB by endemic predators.

 

 

Large larvae
E998 Per day per day

Predator (mean 1 SE) (mean 1 SE)
Lebia grandis adults 47.38 1 2.07 1.91 1 0.55
Coleomegilla maculata adults 7.95 1 0.74 0.33 1 0.10
Peril/us bioculatus 5th instars 39.001 0.211 - - - -
Podisus maculaventris 5th instars -------- 1.002 - . . -
Phalangium opil/io adults 9.63 1 3.253 0.00 - - - -

 

1Tamaki and Butt 1978.
2Drummond et al. 1984.
3Drummond et al. 1988.

118

host. Is desirable. Predator populations may be maintained in the field at low CPB
densities if alternate prey are available.

L. grandis populations are well synchronized with the CPB in both R.I. and Mich.
Predator activity was first detected with the first occurrence of CPB eggs and it peaked
along with peak CPB eggs and larvae. L. grandis oviposition began at 377-378 DD (base
10°C) from April 1. in both regions. The predicted first hatch of L. grandls eggs
occurred 34 days prior to the first observed CPB prepupae In Mich. Since these
parasitic larvae survive an average of 4 days in the absence of a host. It appears that the
parasitic stage of L. grandis Is also well synchronized with its host.

Based on their relatively long development times (28 days at 25°C) and the single
peaks observed In reproducing L. grandis. It Is likely that these predators complete one
generation per year in both regions. A small second peak in reproducing females
observed In late July In Mich. was likely due to overwintered first generation adults
since the predicted first emergence of summer adult L. grandls was on July 19 and in
the laboratory (at 26°C). they appear to have a minimum preovlposltion period of 3-4
weeks. Although L. grandis summer adults do not oviposit until the following summer.
they still may cause significant mortality to the second CPB generation since
prediapausing adults consume a large number of prey. A large peak in prediapausing L.
grandis adults was observed In 1987 in the plot In R.i.. where CPB populations were
high. This peak was not observed in Mich.. where there were very few second generation
CPB. and the predators probably dispersed on emergence.

Tethering CPB prepupae proved an effective means of evaluating the impact of the
parasitic stage of L. grandis. Although some mortality was experienced due to tethering.
it generally did not occur until the individual attempted to molt to the adult. hence it did
not Interfere with the evaluation of parasitism. Parasitism of tethered CPB Indicated
that L. grandis larvae were present and active at the KBS site throughout most of the

growing season. Irrespective of host density. L. grandls parasitism was higher In Mich.

119

in 1987 than in 1986. and higher than at the R.I. site in 1987. As this was the second
consecutive year for potatoes at the Mich. site. the higher parasitism levels may reflect
a build up of L. grandis . ln R.I. a large CPB population produced at the primary
research site in 1986 necessitated moving to a site a few miles away In 1987. There
appeared to be fewer L. grandis in the new site. but L. grandis parasitism was detected
In R.i. in 1987 in a small plot adjacent to the 1986 site. L. grandls activity may be
hampered by long-distance rotations.

L. grandis adults were observed at every site we investigated in R.I. and Mich..
including commercial potato growing areas. This study indicates that this species may
be the most Important endemic predator of the CPB. and further studies of the behavior
and survival of L. grandis are necessary to fully assess its potential for managing CPB

populations.

120

LITERATURE CITED

Bruneteau. J. 1937. Reserches sur les enemies naturals dU Doryphore en Amerlque.
Ann. Epiphyties et Phytogenetique. 3: 113-135.

Casagrande. R.A. 1971. An approach to alfalfa weevil management in Michigan. MS
thesis. Michigan State University. East Lansing. Mich.

Chamboussou. F. 1938. Remarques sur Lebia grandls Hentz. Rev. Zool. Agr. 37:
1 65-1 71 .

Chamboussou. F. 1939. Contribution a I'etUde biologlque de Lebia grandis Hentz.
predateur Americain du Doryphore. Ann. Epiphyties et Phytogenetique. 5(3):
387-433.

Drummond. F.A.. R.L. James. R.A. Casagrande and H. Faubert. 1984.
Development and survival of Podisus maculiventrls (Say) (Hemiptera:
Pentatomidae). a predator of the Colorado potato beetle (Coleoptera:
Chrysomelidae). Environ. Entomol. 13: 1283-1286. .

Drummond. F.A.. E. Groden and R.A. Casagrande. 1987. Biology of Oplomus
dichrous (11.8.) and its potential to control the Colorado potato beetle. Environ.
Entomol. 16: 633-638.

Drummond. F.A.. Y. Suhaya and E. Groden. Preadation on the Colorado potato
beetle. Leptinotarsa decemlineata (Say). by Phalagium opilio (L.). J. Econ.
Entomol. (Submitted).

Groden. E. and R. A. Casagrande. 1986. Population Dynamics of the Colorado
potato beetle. Leptlnotarsa decemlineata Say (Coleoptera: Chrysomelidae) on
Solarium berthaultr‘l Hawkes. J. Econ. Entomol. 79: 91 -97.

Harcourt. 0.6. 1971. Population dynamics of Leptinofarsa decemllneata (Say) In
eastern Ontario. Ill. Major population processes. Can. Entomol. 103:1049-
1061.

121

Logan. P.A.. R.A. Casagrande. i-I.i-l. Faubert and F.A. Drummond. 1985.
Temperature-dependent development and feeding of immature Colorado potato
beetles. Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). Environ.
Entomol. 14: 275-283.

Madge. R.B. 1967. A revision of the genus Lebia Latrellle in America north of
Mexico (Coleoptera: Carabldae). Ouaestiones Entomologicae 3: 139-142.

Obrycki. J.J.. M.J. Tauber. C.A. Tauber. and B. Gollands. 1985. Edovum
puttieri (Hymenoptera: Eulophidae). an exotic egg parasitold of the Colorado
potato beetle (Coleoptera: Chrysomelidae): Responses to temperate zone conditions
and resistant potato plants. Environ. Entomol. 14: 48-54.

Riley. C.V. 1871. Third annual report on the noxious. beneficial. and other insects
of the state of Missouri. Horace Wilcox. Jefferson City. MO.

SAS Institute 1985. SAS user's guide: statistics. SAS Institute. Cary. NC.

Tamakl. G. and B.A. Butt. 1978. impact of Perillus bioculatus on the Colorado
potato beetle and plant damage. U.S. Dept. Agric. Tech. Bull. 1581. 11 pp.

MANUSCRIPT 3.

Coleomegilla maculata DeGeer (Coleoptera: Cocclnellidae):
Its Predation Upon the Colorado Potato Beetle
(Coeoptera: Chrysomelidae). and Its Incidence in Potatoes and
Surrounding Crops

ABSTRACT - The polyphagous coccinellid. Coleomegilla maculata DeGeer. was found to
feed on the eggs and small larvae of the Colorado potato beetle (CPB). Leptlnotarsa
decemlineata (Say). Prey consumption rates were highly correlated with temperature.
in choice tests this predator did not prefer aphids over CPB larvae. but as aphid
densities Increased. consumption of CPB larvae decreased. Field cage studies
demonstrated that C. maculata adults have the potential to significantly reduce
populations of CPB eggs and small larvae.

The incidence of C. maculata adults was monitored In early and late planted potatoes
In R.I. and Mich. This predator was well synchronized with first generation CPB prey In
early planted potatoes in both states. and with second generation CPB prey In late planted
potatoes in R.I. C. maculata adult densities were monitored In crops surrounding
potatoes at one Mich. site. These included coie crops. snap beans. cucurbits. and sweet
corn in 1986. and alfalfa and sweet corn In 1987. The predator was found in all crops.
with highest densities observed in sweet corn during pollen production. Using observed
temperatures and phenologlcal models from the literature. we determined that C.
maculata has the potential to complete 2-3 generations per year in R.I.. and 34

generations per year In Mich.

122

123

INTRODUCTION

Much biological control research has focused on the Interactions between
coccinellids and aphids In potato fields (Shands and Simpson 1972; Mack and Smilowitz
1978. 1980. 1982a. b; Mack et al. 1981. Shands at al. 1972 a.b; Tamakl 1981). but
little attention has been given to the impact of these species on the Colorado potato beetle
(CPB). Laptinotarsa decemlineata (Say). Riley (1869. 1871. 1872. 1873) observed
six coccinellid species feeding on CPB eggs and larvae. Of these. we have found the
spotted ladybird. Coleomegilla maculata DeGeer to be the most abundant species in
potatoes In R.i. and Mich. We also observed this species feeding on the CPB on wild host
plants in Mexico and Mich.

C. maculata Is a polyphagous predator which Gordon (1985) reports to be
primarily aphidaphagous. It has been commonly reported feeding on aphids in potatoes
(Mack and Smilowitz 1980). corn (Ewart and Chiang 1966). and alfalfa (Hodak 1973).
Wright and Laing (1978) suggest that It is found on most crops supporting aphid
populations. 0. maculata has also been reported to be an important egg predator of the
European corn borer. Ostrinla nubile/ls (Hbr.) (Bartholomai 1954. Conrad 1959) and
the bollworm. Heliothus zea (Boddie) (Whitcomb and Bell 1964). Smith (1961)
found that this predator can also complete development when reared solely on pollen.
Consumption rates have been determined for this predator feeding on aphids (Mack at al.
1981). but Its potential impact on the CPB is unknown.

The objectives of this study were to daterrnine the impact of adult 0. maculata on
the CPB In the laboratory and in field cage studies. and to Investigate its occurrence in
potato fields in R.I. and Mich. This study was part of a larger project Investigating
natural mortality of the CPB.

124

MATERIALS AND METHODS

Consumption rates. in August 1986 and 1987. C. maculata adults were
collected from potato research fields in Mich. and R.I. to determine their daily
consumption of Immature CPB stages. Predators were sexed and held individually in
petri dishes with moist paper toweling and prey In excess of their daily consumption.
Forty predators were given either 20-33 eggs. or first. second. third. or fourth Instar
CPB larvae (densities - 25. 7. 4 and 2 respectively) and held for five days at 22-23°C.
Prey consumption was monitored and new prey added daily. To determine the Influence
of temperature. C. maculata consumption of CPB eggs was monitored at constant
temperatures of 15. 20. 25. and 30°C (n - 25 per temperature). Predators were
handled as descrbed above and pray consumption checked daily. for e13 days. An
analysis of covariance (SAS Institute 1985) was performed to determine If consumption
varied with the sex of the predator (with temperature as the covariate. SAS Institute
1 9 85).

Another laboratory study was conducted to determine If C. maculata consumption of
first instar CPB larvae was Influenced by the presence of aphid prey. in the second week
In May. 1987 ca. 500 C. maculata adults were collected in alfalfa fields near East
Lansing. Mich. The adults were held at 22°C in ventilated 1 liter plastic cups for 24 h
(25 C. maculata per cup). after which sluggish individuals or those parasitized by
Perllltus coccinellae (Shrank) were eliminated from the study. The healthy C. maculata
adults were held Individually in 30.5 cm capped glass lantern globes. The globes were
set over 1 liter plastic cups of sand. each with a single Solarium dulcamara L. leaf
(trimmed to a standard 20 cm2) held In a water-filled floral stem holder embedded In
the sand. 8. dulcamara was chosen as a host because all prey fed on this host. and unlike
S. tuberosum . the stems remained turgid over the 24 h duration of the experiment. Ten
first instar CPB larvae were transfered to each leaf. and non-slate aphids were added at

125

densities of 0. 10. 15. 20. 25. 30. or 35 per leaf. Two aphid species were tested.
Eleven replicates of each density were established with the green peach aphid. Myzus
persicae (Sulzer). and 5 replicates of each density were established with the potato
aphid. Macrosiphurn euphorbiae (Thomas). into each globe. a single C. maculata adult
was released. The globes were held at 28°C with a photoperlod of 15 L:9 D for 24 h..
after which the CPB larval and aphid densities were recorded. Linear regression
analysis (SAS institute 1985) was used to determine the effect of aphid prey density on
consumption of CPB larvae by C. maculata adults.

Cage studies. The Impact of C. maculata on CPB mortality. was investigated in
R.i. in August. 1986 using six screen walk-In cages (3.6 x 1.8 x 1.8 In). These cages
were erected in a newly tilled area and Into each cage two rows of 10 greenhouse-grown
potato plants were transplanted. Potato stems infested with CPB egg masses were
collected from nearby research plots. and bouquets of stems were placed In 6-inch
pyrex test tubes with water. and the tops of the tubes were sealed with parafiim. These
bouquets were set within the cages with the test tubes sunk Into the soil so that the CPB
infested stems stood within the stems of the transplanted plants. Bouquet stems were
secured to existing stems to assure that they did not droop away from the plant.
Resulting CPB egg densities in the cages were set at 500 eggs per cage In 3 cages. and
250 eggs per cage In 3 cages.

At each of these prey densities. C. maculata adults were introduced at densities of
0. 10 and 20 predators per cage. CPB eggs and larvae within each cage were censused
every 3 to 4 days for three weeks. A two-way analysis of variance (SAS Institute
1985) was performed for each weakly interval to determine effects of intlal egg and
predator densities on prey survival. The data were pooled for the first two sample dates
(representing the egg and first instar stages of the prey) and all predator cages to
examine the relationship between prey density and consumption rates. Available pray at

126

the beginning of each sampling interval was regressed with consumption per predator
over the Interval.

Field incidence. The densities of C. maculata and the CPB were sampled in early
and late planted potatoes at two sites in Mich. and two sites In R.I. from 1985-1987. In
Mich. these included a late planting In 1985. and an early and adjacent late planting In
1986 and 1987 at the Michigan State University Kellogg Biological Station (KBS) In
Hickory Comers. Mich.. and at the Michigan State University Potato Research Station In
Stanton. Mich. An additional isolated third site with late planted potatoes at KBS was
sampled In 1986 and 1987. In R.i. early and Isolated late plantings were established at
different sections (separated by 1 km) of the University of Rhode Island research farm
In Kingston. R.i. The fast maturing potato cultivar Caribe' was used at all sites. Seventy
to 150 whole plant samples were taken at each site per sample data using nondestructive
visual counts of all predators and CPB lifestages on a plant.

Given the mobility and polyphagous feeding habits of this predator. we felt that to
understand the seasonal dynamics of C. maculata in potatoes. it was necessary to follow
Its populations In surrounding crops. In 1986 C. maculata densities and their prey
were monitored in plots of alternate crops surrounding the potato research fields at the
KBS sites including coie crops (broccoli and cabbage). snap beans. sweet corn. and
curcubits (squash and cucumber). Nondestructive whole plant counts of C. maculata
and possible prey were taken In each plot once per week throughout the growing season
with samples of 50 plants for coie crops. 30 for beans. 75 for sweet corn. and 60 for
cucurbits. in 1987. at these same sites. 0. maculata and their prey were monitored In
two alfalfa fields and two sweet corn plots. Ten samples consisting of 10 consective
sweeps with a 36 cm diameter sweepnat were collected In the alfalfa once per week. and
25 visual whole-plant samples In each of three varieties of sweet corn were taken once

per week from the pre-tassei stage through harvest.

127

Pesticides were not used in any plots at the KBS site In Mich. or any site in R.i..
during the study. Weeds were controlled by mechanical cultivation. At the Montcalm
research site In Mich.. a pre-emergence herbicide and regular fungicide treatments
were applied. as Is standard for potato production In this area.

Daily maximum and minimum temperatures were recorded In a Stevenson screen
located at each of the three research sites starting April 1 each year. From these
temperature data. degree-day accumulations were calculated for the following C.
maculata physiological events using published degree-day models: first oviposition by
overwintered C. maculata females (82.200 > 15.400. Wright and Laing 1978). fetal
development for immature stages (198.800 > 13.800. . Wright and Laing 1978. and
236°D > 11.3°C. Obrycki and Tauber 1978). and praoviposltion by summer adults
(220D > 13.8%. Mack and Smilowitz 1982b). Degree-day accumulations were
calculated by [(T max + Tmin)/2]-t when Tmin > t and [Tmax + t)/2]-t when Tmin < t
(Baskervllle and Emin 1969). Predictions were made for first emergence of each C.
maculata generation by accumulating degree-days for development and preovlposltion
from the predicted first oviposition by overwintered adults.

RESULTS
Consumption Studies. 0. maculata adults consistently consumed the eggs and
small larvae of the CPB (T able 1). Most individuals which were fed only third Instar
CPB larvae consumed a minimum of one larva throughout the study. Only two of the
individuals which were fed only fourth instar larvae successfully consumed these prey .
An adult C. macualata was also observed attacking a fourth instar CPB larva in the field.
There was a significant difference In egg consumption between sexes in adult C. maculata

128

Table 1. Consumption of immature stages of the CPB by Coleomegilla
maculata De Gear adults.

 

Daily consumption

 

per predator
CPB Stage Sample Size (mean 1 SE)
Ea 1 0 7.95 1 0.74
151 Instars 10 11.20 1 0.78
2nd Instars 10 3.07 1 0.31
3rd Instars 5 0.60 1 0.16

4th Instars 5 0.13 1 0.09

 

1 2 9
(F(1.600) - 49.2. p - 0.001). Over all temperatures. females consumed 9.10 1 0.24
eggs per day (mean 1 SE). whereas. males consumed 6.64 1 0.30 eggs per day (mean 1
SE). Consumptions rates of C. maculata adults were linearly correlated with
temperature over the range of temperatures tested (Figure 1).

The presence of both aphid species had an effect upon consumption of first Instar
CPB larvae by C. maculata adults (F05) - 21.35. p - 0.004 for Myzuz perslcae : and

F(1.6) - 3.61. p - 0.106 for Macrosiphum euphorbiae ). Consumption of first Instar
CPB larvae decreased In a linear manner as aphid density Increased (Figure 2. y -
7.514 - 0.078 x. r2 - 0.78 for Myzuz persicae; and y - 7.218 - o.os1x. r2 - 0.38
for Macmsiphum euphorbiae ). C. maculata adults consumed a fairly constant
proportion of the both aphid species. 78.5 11.5 % (mean 1 SE) for Myzus perslcae
and 71.3 1 2.8 % (mean 1 SE) for Macrosiphum euphorbiae .

Cage studies. C. maculata adults significantly reduced the survival of CPB

cohorts In the cage study over the first week of the study (Figure 3). A significant
predator density efiect (FIZZ) - 19.24. p - 0.049). and a significant egg density

efiect (File?) - 19.4. p - 0.048) on CPB survival was observed over this period.
There was. however. no significant difference In CPB survival between cages In the later
two weeks of the study (fizz) - 0.48. p - 0.67). This predator impacted the egg and
first Instar larval survival only. The relationship between prey density and predator
consumption rates as shown In Figure 4. may be described by the function: y . -1.31 +
0.69(Iog x). r2 - 0.82.

Field Incidence. In R.I. In all three years studied. 0. maculata incidence in
potatoes was well synchronized with CPB prey (eggs and first and second Instar larvae)
in both early and late planted potatoes (Figure 5). Adult 0. maculata colonized early
potatoes between June 3 and June 9. Their population densities peaked 7-14 days after
the peak In prey density. In the late plantings. C. maculata adults were detected prior to

130

 

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135

or with the first available CPB prey. In 1986 and 1987, predator densities were
similar in the early and late plantings. however the predatorzprey ratio was 10- to 30-
fold greater in the late plantings.

In Mich., adult 0. maculata populations in potatoes responded to CPB prey in early
plantings in 1986 and 1987. but not In the late plantings (Figure 6 and 7). Population
trends were similar at all Mich. sites. 0. maculata adults colonized early planted
potatoes at the KBS site on June 9 in 1986. and June 7 in 1987. At the Montcalm site 0.
maculata adults were first observed in potatoes on June 19 in 1986. and June 3 In
1987. The later first occurrence of C. maculata at this site in 1986 coincided with a
later build-up of CPB prey. C. maculata densities in potatoes in Mich. varied
considerably between years and sites irrespective of CPB prey densities.

Of the different crops surveyed at KBS in 1986 and 1987, C. maculata adults were
found in all plots at some point during the season. In 1986. potatoes were the earliest
crop colonized by C. maculata adults (Figure 8). and these adults were consistently
found at low densities in this crop throughout the field season. The cole crops and beans
at site 1 were also colonized early in early June. The predator was found only once in
broccoli and cabbage plots at site 2. Predator populations did not appear to coincide with
aphids on these crop plants. Aphids were present intermittently and at very low
densities in these crops at both sites. 0. maculata incidence in cole crops at site 1
roughly coincided with Plerls rapae (L.) egg populations. Immature Mexican bean
beetles. Epilachna varivestris Mulsant. were also an apparent prey for C. maculata on
snap beans. (The predators readily consumed both E. varivestnis eggs and small larvae
in the laboratory.) 0. maculata adults colonized the cucurbits in early July. No aphids
were observed on these crops, however they were heavily infested with cucumber
beetles, Diabrotica undecimpuctata howardi Barber, and Acalymma viftafa (Fabricius),
and squash bugs, Anasa tristics (De Gear). In 1986. the sweet corn at both sites was

136

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138

 

   
 

 

 

 

 

 

 

 

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MAY 20 JUNE 30 Aucs SEPT17

Figure 8. Densities of Coleomegilla maculata adults in potatoes and surrounding crops
at the K88 site in Michigan, 1986.

139

colonized in July at the onset of tasseling when the tassels at both sites were heavily
Infested with aphids. Between the two peaks (Figure 8) in adult C. maculata populations
in corn. C. maculata larvae were abundant. This crop supported the highest densities of
this predator.

In 1987, C. maculata adults were sampled In alfalfa on April 24 (Figure 9). The
populations declined in field 1 following the first cutting in mid May. and declined in
field 2 prior to the first cutting in late May. This decline in field 2 coincided with a drop
in aphid populations In this field (Groden 1988). C. maculata adults colonized potatoes
in early June, and sweet corn again in early July. C. maculata densities were low in
alfalfa throughout the month of June. but increased again in late July and August. Three
peaks in adult densities are evident in potatoes. and two In sweet corn (Figure 9). C.
maculata populations in potatoes were greater in 1987 than 1986. but about the same
between years in corn.

The predicted C. maculata physiological events differed between Mich. and R.I. by as
much as 25 days by the and of the seaan able 2). Due to the cooler spring
temperatures in R.I.. the predicted first oviposition by overwintered adults was 12 to
14 days later than in Mich. in 1986. and 9 to 17 days later In 1987. In R.I. C. maculata
had the potential to complete 2 or 3 generation In 1986. and 3 generations in 1987. In
Mich.. it had the potential to complete 3 generations in 1986. and a possible fourth in
1 987.

DISCUSSION
C. maculata is an important natural enemy of the CPB. It fed readily on CPB eggs
and small larvae in the laboratory. and It has frequently been observed feeding on these
pray In the field. Although some individuals fed on large larvae when confined In a petri
dish. it is doubtful that C. maculata would handle such large pray in the field. The field

140

05 - C. maculata DENSITY

1 ——o-— srre 1 EARLY PLANnNe
0.4 - POTATO —0— SITE 1 LATE PLANTING
. —o—‘ SITE 2

0.3-

0.2-1

0.1 -'

MEAN PER PLANT

 

 

°-° '. . . ' 1.
0.5 .
0.4 -

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03 -

 

0.2 -1

0.1 '1

MEAN PER PLANT

 

 

 

00° ' I v ! ' ! v I.

MEAN PER 10 SWEEPS

 

 

 

APRIL 20 JUNE 10 JULY 20 SEPT 17

Figure 9. Densities of my; mums In potatoes and surrounding crops at the
KBS site in Michigan, 1987.

141

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142

cage study also demonstrated that this predator can significantly reduce populations of
CPB eggs and small larvae, but it has no impact on large larvae. C. maculata adult
predation increased with increased prey densities.

The predators's CPB consumption was reduced in the presence of alternate prey.
Given the linear reduction in CPB consumtion as aphid density increased, and the
constant proportion of aphids preyed upon, we conclude that C. maculata adults do not
preferentially feed on aphids. but feed on whichever prey type they encounter.
Therefore. high aphid densities in potatoes will decrease the effectiveness of C. maculata
as a CPB predator. In evaluating the polyphagous behavior of C. maculata. Smith
(1965b) demonstrated that previous feeding experience did not affect its food
preference. and he also reported preferential feeding on corn pollen by C. maculata
adults in choice tests with aphids. We are not able to determine from this study the
Impact of alternate food sources In adjacent crops on the densities of C. maculata in
potatoes. With the higher densities in sweet corn in the July and August. and C.
maculata' 3 known preference for corn pollen. it may be possible that this crop In close
proximity can draw these predators out of crops with less prefered food.

in the early season, 0. maculata adults colonized potatoes when suitable CPB prey
became available. Other suitable prey were not available on potatoes at this time.
Although potato aphids can be found on potatoes in Mich. in early June. their populations
do not build up until mid-July and August. Green peach aphids are also a late season pest
on potatoes. Aphld densities from the Montcalm research site In 1986 and 1987
(Grafius. unpublished data) confirm that in both years 0. maculata colonized the plots
prior to aphids.

in the late season. the diversity of prey types available on potatoes and surrounding
crops increases. C. maculata populations are likely responding to total suitable prey
densities. Generally. Mich. has a much smaller second CPB generation than R.I. The

143

synchrony of C. maculata adults with the second CPB generation In R.I. may reflect the
fact that the CPB constitutes a larger proportion of the predator's total available prey.
Aphid build-ups in potatoes and other surrounding crops in conjunction with smaller
CPB populations may be responsible for the lack of synchrony with CPB in the late
season in Mich.

At the K38 site. 0. maculata was first observed in late April in 1986 and 1987.
feeding on pollen of dandelions. Taraxacum officinale Weger. surrounding alfalfa. In
1986. these predators had colonized alfalfa by May 10. and in 1987 they were abundant
in this crop on April 26. more than one month prior to the first observance in potatoes.
The predicted first C. maculata oviposition at the KBS site was on May 13 in 1986. and
May 14 in 1987. C. maculata females collected at this site on May 10 in 1986. were
ovipositing. as were females collected on May 24 in 1987. Obrycki and Tauber (1979)
reported that photoperlodic control of diapause in this species ends in March in New
York. and suggest that after this point the availability of food sources as well as
temperature could be influencing factors. There is abundant supply of aphids In alfalfa
in Mich. in early May. and with suitable temperatures. over-wintered C. maculata
females may begin ovipositing in this crop before potatoes break ground.

The predicted first emergence of first generation adults in Mich. was between June
19 and June 24 in 1986. and between June 9 and June 11 in 1987. This predicted
emergence in 1987 coincided with the initial colonization of potatoes by C. maculata
adults. indicating that in some years in Mich.. this predator may have the potential to go
through one complete generation before colonizing potatoes. 0. maculata had the
potential to complete 3 generations in 1986. and 4 in 1987. in 1986. one generation
was likely completed before the predators colonized cucurbits or sweet corn. In 1987.

they apparently completed two generations before colonizing sweet corn.

144

The predicted physiological events do not coincide with the observed dynamics of
adult 0. maculata populations sampled at KBS in 1986. although they do in 1987. Many
factors not accounted for in these predictions can influence the observed changes in this
predator‘s populations. Mortality can shift the population curves if it is not constant
throughout the generation. Different prey types and the consistancy of the prey supply
has also been shown to Influence development rates of this species (Putman 1957. Smith
1960, 1961. 1965a.c). And crop management practices. such as cutting alfalfa. can
strongly Influence C. maculata mortality and dispersal to different crop plants.
Therefore. these predictions reflect the potential generations of C. maculata at each of
the study sites given optimal conditions. A better understanding of the consequences of
these factors on the behavior. mortality. and movement of these predators in the fleld is
necessary before they can be effectively managed to maximize their impact upon the
CPB.

145

LITERATURE CITED

Bartholomal, CAN. 1954. Predation of European corn borer eggs by arthropods. J.
Econ. Entomol. 47: 295-299.
Baskervllle, G.L. and P. Emin. 1969. Rapid estimation of heat accumulation from
maximum and minimum temperatures. Ecology 50: 514-517.
Conrad, MS. 1959. The spotted lady beetle. Coleomegilla maculata DeGeer). as a
predator of European corn borer eggs. J. Econ. Entomol. 52: 843-847.
Ewart. M.A. and H.C. Chiang. 1966. Dispersal of three species of coccinellids in
corn fields. Can. Entomol. 98: 999-1003.
Gordon 1985. North American Coccinellidae. J. N.Y. Entomol. Soc. 93(1): 1-912.
l-lodek, i. 1973. Biology of the Coccinellidae. Academia Press. Prague.
Mack, T.P. and z. Smilowitz. 1978. Diurnal. seasonal, and relative abundance of
Myzus perslcae (Sulzer) predators. J. N.Y. Entomol. Soc. 86: 305.
1980. Development of a green peach aphid natural enemy sampling procedure.
Environ. Entomol. 9: 440-445.
1982a. Using temperature-mediated functional response models to predict the
impact of Coleomegilla maculata (DeGeer) adults and third instar larvae on green
peach aphids. Environ. Entomol. 11: 46-52.
1982b. CMACSIM. a temperature-dependent predator-prey model simulating the
Impact of Coleomegilla maculata (DeGeer) on green peach aphids on potato plants.
Environ. Entomol. 11: 1193-1201.
Mack, T.P., B.A. Balusz, as. Nolan and Z. Smilowitz 1981. Development of a
temperature-mediated functional response equation. Environ. Entomol. 10: 573-
579.

146

Obrycki, J.J. and M.J. Tauber. 1978. Thermal requirements for development of
Coleomegilla maculata (Coleoptera: Cocclnellidae) and Its parasite Perilitus
coccinellae (Hymenoptera: Braconidae). Can. Entomol. 110: 407-412.

1979. Seasonal synchrony of the parasite Perilitus coclnellae and its host
'Coleomegma maculata. Environ. Entomol. 8: 400-405.

Putman, “LL. 1957. Laboratory studies on the food of some coccinellids (Coleoptera)
found in Ontario peach orchards. Can. Entomol. 89: 572-579.

Riley, ON. 1869. First annual report on the noxious, beneficial. and other insects of
the state of Missouri. Ellwood Kirby. Jefferson City, MO. 182 pp.

1871. Third annual report on the noxious. beneflcial, and other insects of the state
of Missouri. Horace Wilcox. Jefferson City. MO. 176 pp.

1872. Fourth annual report of the noxious. beneficial. and other insects of the state
of Missouri. Regan and Edwards. Jefferson City, MO. 115 pp.

1873. Fifth annual report of the noxious. beneficial. and other insects of the state of
Missouri. Regan and Edwards. Jefferson City. MO.

Shands, W.A. and 6.1". Simpson. 1972. Insect predators for controlling aphids on
potatoes. 2. In small plots with two kinds of barriers. in small fields. or in large
cages. J. Econ. Entomol. 65: 514-518.

Shands, W.A., G.W. Simpson and M. H. Bronson. 1972a. insect predators for
controlling aphids on potatoes. 1. In small plots. J. Econ. Entomol. 65: 511-514.

Shands, W.A., c.w. Simpson and R.i-i. Storch. 1972b. insect predators for
controlling aphids on potatoes. 3. in small plots separated by aluminum flashing
stripe-coated with a chemical barrier and in small fields. J. Econ. Entomol.
65:799-805.

147

Smith, 8.6. 1960. A technique for rearing coccinellid beetles on dry foods. and
influence of various poliens on the development of Coleomegilla maculata Iengi
Timb. (Coleoptera: Coccinellidae). Can. J. Zool. 38:1047-1049.

1961. Results of rearing some cocineliid (Coleoptera: Coccinellidae) larvae on
various poliens. Proc. Entomol. Soc. Ont. 91:270-271.

1965a. Growth and development of cocineliid larvae on dry foods (Coleoptera:
Coccinellidae). Can. Entomol. 97: 760-768.

1965b. Effects of food on the longevity, fecundity. and development of adult
coccinellids (Coleoptera: Coccinellidae). Can. Entomol. 97: 910-919.

1965c. Differences in Anaris mall Auct. and Coleomegilla maculata Iengl
Timberlake to changes in the quality and quantity of the larval food (Coleoptera:
Coccinellidae). Can. Entomol. 97: 1159-1166.

Tamakl, G. 1981. Biological control of potato pests. Quantitative approaches to
biological control. pp. 178-192. In: J.H. Lashomb and R.A. Casagrande (eds.).
Advances in potato pest management. Hutchinson Ross Publishing Co.. Stroudsburg.
PA. 289 p.

Whitcomb, WM. and K. Bell. 1964. Predaceous insects. spiders and mites of
Arkansas cotton fields. Arkansas Agr. Exp. Sta. Bull. 690.

Wright, EJ. and J.E. Laing. 1978. The effects of temperature on development.
adult longevity and fecundity of Coleomegilla maculata Iengl and its parasite.
Perilitus cocaine/lee. Proc. Entomol. Soc. Ont. 109:33-47.

MANUSCRIPT 4.

Effects of Soil Funglstasis on Beauveria bassiana (Bais) Vuill.
and its Relationship to Disease incidence in the
Colorado potato beetle, Leptlnotarsa decemllneafa (Say)
in Michigan and Rhode island Soils

ABSTRACT - The fungistatic effects on Beauveria bassiana were measured in soils
collected from two potato fields each in Rhode island and Michigan for two years.
Michigan soils were more fungistatic than Rhode island soils in 1986. but fungistasis
levels varied between years. and in 1987 one Michigan soil was significth more
fungistatic than the Rhode island soils. Fungistasis levels were found to increase
exponentially with increases in soil pH. Pupae of the Colorado potato beetle,
Leptinotarsa decemlineata (CPB) were inoculated with B. bassiana conidia and
immediately incubated in the Michigan and Rhode island soils to determine if a
relationship exists between fungistasis and disease incidence. There was no significant
soil effect on CPB mortality. but iog-probit regressions of dose-mortality against
fungistasis levels revealed a significant trend of increasing L050 values with increasing
fungistasis. There also were significant soil and dosage effects on B. bassiana
sporulation in pupae previously inoculated with B. bassiana. More sporulation was
found on individuals in Rhode island soils than in Michigan soils.

148

149

INTRODUCTION

Beauveria bassiana (Balsamo) Vuiilemln Is a soil-borne pathogen of many insect
pests. and its potential development as a microbial insecticide has heightened interest in
its ecology in soils. Several authors have reported the inhibition of germination of B.
bassiana conidia in natural (non-sterile) soils (Wartenburg and Freud 1962. Clerk
1969. Walstad et al. 1970. Lingg and Donaldson 1981. and Sharapov and Kalvish
1984). This inhibition was overcome by autoclaving the soils. by filtering soil extracts
(Clerk 1969). or by the addition of organic amendments to soils. Walstad et al. (1970)
demonstrated the fungistatic versus fungitoxic nature of this phenomenon. and it has
been suggested that the inhibitory effects of soil are counteracted by the presence of
insect hosts (Wartenberg and Freud 1961. Clerk 1969). As the level of fungistasis
against B. bassiana has been shown to differ in different soils (Sharapov and Kalvish
1984). knowledge of the relationship between soil fungistasis and B. bassiana infection
is necessary for determining effective inoculum dosages for adequate pest control under
different soil conditions.

The purpose of this study was to quantify B. bassiana fungistasis in soils from
potato fields in Rhode Island and Michigan. and to determine whether a relationship
exists between fungistasis and mortality of Colorado potato beetle (Leptinofarsa
decemlineata (Say) pupae inoculated with B. bassiana.

MATERIALS AND METHODS
Fungal Culture. A pure culture of Beauveria bassiana strain R8252 was
obtained by inoculating plates of Sabouraud's maltose agar (SMA) plus 650 ppm. dodine
(Beiiharz and Parbery 1982) with a technical grade. foliar formulation of the fungus
obtained from Abbott Laboratories. N. Chicago. ii. 8. bassiana was maintained on SMA.
and conidia for use in experiments were harvested from two- to three-week-old

cultures on the same medium. Conidia were collected directly from plates with a sterile

150

transfer loop and added to distilled water. The resulting concentration of conidia was
determined by counting the conidia in a 1 mi droplet with a hemocytometer. The
concentration was adjusted as needed by making dilutions in distilled water.

Soils. Soil samples were collected from two potato research sites at the
University of Rhode island Research Farm in Kingston, Rhode island. and two potato
research sites in Michigan. The Rhode island soil samples included an Enfieid silt loam
from the Agronomy farm site. and a Merlmack sandy loam from the Peckham Farm site.
The Michigan soils included a McBride sandy loam from the Michigan State University
Potato Research Farm in Montcalm 00.. Michigan. and a Kalamazoo sandy loam from the
Michigan State University Kellogg Biological Station (KBS) in Kalamazoo 00.. Michigan.
01 these sites. all except the KBS site are within commercial potato growing areas with
high regional populations of the CPB. In 1986. soil samples were collected in August
(R.i.) and September (Mich). and in 1987. all samples were collected in August. in all
cases. soil was collected from an area currently planted to potatoes. Solanum tubemsum
L At the Montcalm site. herbicides were the only pesticides used during the two years
sampled. and at all other sites. no pesticides were used. Vertical movement of
commercially fonnuiated B. bassiana conidia has been found to be restricted primarily
to the top 15 cm of soil (Storey et al. 1987). For this study. only soil within 10 cm of
the soil surface was used. Soils were solved (2 mm mesh) and stored moist in air-tight
containers at 4.400 for 3-6 months prior to use.

Characterization of the soils collected in 1987 included textural analyses. cation
exchange capacity and organic matter content determined by the Soil Testing Laboratory.
Michigan State University. in addition. organic carbon content was determined by the
method described by Allison (1965). and pH was determined with an electronic pH
meter. Moisture characteristic curves for the soils were determined using a pressure-

piate apparatus (Richards 1965). Second order polynomial equations were fit to each of

151

the curves for predicting the appropriate percentage of moisture for a given water
potential. Soil pH was also determined for the samples collected in 1986.

Funglstasis Assay. A quantitative determination of fungistasis in the different
soils was made by assessing the germination of B. bassiana conidia on 10-mm-diameter
membrane filters (Gelman. iGA-8. pore size 0.2 microns) placed on soil supplemented
with increasing concentrations of a 5:1 (w:w) solution of glucose and peptone. Ten g
(dry weight) samples of the soils were measured and tamped to a smooth surface in 6-
crn-diameter glass petri dishes. One ml glucose-peptone solution was added to each dish.
Concentrations of glucosepeptone previously determined to yield an appropriate range of
B. bassiana germination in soil were 10.0002000. 5000:1000. 2500:500.
1250:250. 625:125. and 0:0 ug/g soil. After the addition of the nutrient solution. the
soil was wet to saturation and the soil surface smoothed. Sterliized membrane filters
bearing B. bassiana conidia were placed on the soil surface. B. bassiana conidia were
aseptically transfered to the filters by pipetting 4 ul of a conidiai suspension (100-200
conidia/pi) on each filter with a repeating micropipette. The dishes were then incubated
at 22°C for 22 hours in moisture chambers to maintain high relative humidity. After
incubation. the filters were removed and the bottoms were carefully pulled over moist
filter paper to remove adhering soil particles before staining with phenolic rose bengai.
Stained fllters were then placed on glass slides and dried. Dried filters were cleared
with mineral oil and viewed with transmitted light at 300x magnification to determine
the percentage of germinated conidia. Two replicate dishes of each soil with three fliters
per dish were used per glucose concentration for the 1986 soil samples.

Using soil samples collected from the same sites in 1987. this experiment was
repeated once with the above range of giucose:peptone concentrations and again with a
giucose:peptone concentration of 312.5:125 (Lg/g soil. Two dishes of each soil were
used with four inoculated fliters per dish. in the 1987 test. due to a change in the

polymer used in the manufacture of the membrane filters (GA-BS). it was necessary to

152

use cinnamon oil to clear the filters for viewing the conidia. In both years. 100-200
conidia per filter were counted.

Probit transformations of germination percentages were regressed on the log
concentrations of glucose for each soil, and the glucose concentration necessary for 50%
germination was determined. An analysis of covariance (SAS institute 1985) with
glucose as the covariate was performed to detect significant difference between
fungistasis levels (% germination) in the different soils. Data from fungistasis assays
for both years were pooled. and regression analyses were used to explore the functional
relationships between fungistasis levels (represented by the estimated glucose
concentration necessary for 50% B. bassiana germination) and soil pH. and fungistasis
levels and soil texture (represented by % sand and % silt). Data from the 1987
fungistasis assay were used to regress fungistasis levels on 96 organic matter. and
fungistasis levels on % carbon.

As 8. bassiana is an insect pathogen. and conidiai germination has been shown to
be stimulated by insect cuticles (Walstad et al. 1970),we were interested in
determining if chitin. a major component of the insect cuticle. was a more appropriate
amendment with which to assay fungistatic effects of soils on B. bassiana. First. the
germination of B. bassiana on colloidal chitin was compared with that on ground eiytra
from CPB adults.

Colloidal chitin was prepared from unbleached chitin flakes as described by Hsu and
Lockwood (1975). was autoclaved and stored in suspension. The final suspension
contained 0.042 g chitin/mi. For the assays, this concentrated suspension was diluted
by adding 1 ml to 9 mi of distilled water. and autoclaved. Elytra removed from two adult
CPB were ground with a mortar and pestle and sterilized in aqueous suspension. Both the
chitin and eiytra particles were deposited aseptically onto 25-mm-diameter Gelman
membrane filters (pore size 5 pm). These filters were transferred to sterilized 6-cm-

diameter petri dishes containing two water-saturated filter papers. Ten-mm-dlameter

153

membrane filters bearing B. bassiana conidia (as described above) were placed over
each substrate. and dishes were held in moisture chambers for 22 hours. After
incubtion. the filters were stained and prepared for examination of B. bassiana conidiai
germination. Three dishes each containing one inoculated filter were used; these were
compared with controls of inoculated filters on saturated filter paper. A one-way
analysis of variance (SAS institute 1985) was performed to compare the germination
data.

A second experiment was conducted to determine the influence of colloidal chitin
on the gerrninatlon of B. bassiana conidia in the presence of soil. and to determine the
effects of different concentrations of chitin on conidiai germination on soil. The colloidal
chitin suspension was sterilized and deposited onto membrane filters as described above.
with resulting concentrations of chitin per filter equaling 4.2 mg. 2.1 mg. 1.05 mg.
0.525 mg. and 0 mg. Two filters per chitin concentration were transferred to 6-cm-
diameter petri dishes containing 10 g saturated. tamped soil collected from the KBS site
in Michigan in 1987 (a single dish for each filter). Controls consisted of two filters per
chitin concentration placed on two saturated filter papers in sterile petri dishes. Filters
bearing B. bassiana conidia were placed on the chitin and the dishes were incubated in a
moisture chamber for 25 hours. before filters were stained and prepared for
observation. Membrane filters with B. bassiana conidia were also incubated on SMA for
25 hours as a check on conidiai viability. A two-way analysis of variance was applied to
the data (SAS institute 1985).

A third experiment was conducted comparing the germination of B. bassiana
conidia on 4.2 mg chitin using the 1987 soil samples from Rhode island and Michigan.
Soil treatments were prepared as described for the previous experiment. Two B.
bassiana membrane filters per soil type were incubated for 24 hours. and two filters
per soil type were incubated for 43 hours. Controls included two filters incubated on

154

chitin on saturated filter papers and two on SMA, both incubated 24 hours. After
incubation. filters were stained and prepared for observation.

Dose-mortallty Study. The mortality of CPB pupae inoculated with B.
bassiana was determined in the difierent soils collected in 1987 and without soil.
Diapausing CPB adults were collected in August. 1987. at the KBS site. and held in cold
storage at 4°C for 3 months before rearing was initiated. After removal from cold
storage. beetles were maintained on greenhouse grown potato plants in a rearing room
with a 16:8 lightzdark cycle. and temperatures ranging between 24-26°C. Egg masses
were transferred daily to larval cages. where upon hatch. they fed on potato foliage until
completion of the fourth stadium when the prepupae were collected. Prepupae were held
at 26°C until pupation. after which they were transfered to 15°C until used for this
study.

Sixteen 50-g (dry weight) samples of each of the four different soils were
measured into 1 pint plastic containers. in each sample the percentage moisture was
increased to the level necessary to equilibrate the soils at a water potential of -0.33
bars. Ten CPB pupae were individually placed ventral side down in each of eight of the
containers per soil type.‘ in addition to the soil treatments. 10 pupae were placed
ventral side down on 3 layers of saturated filter paper in a 10-cm-diameter glass petri
dish. The physiological age oi the pupae ranged from s to 35 degree-days (base 10°C;
total pupal development time - 76 degree-days). Pupae were distributed such that the
age structure of the 10 pupae was equal across all containers. Once placed on the soil or
filter paper. each pupa received two 3-ui drops of a B. bassiana conidiai suspension on
its dorsal surface. Each pupa received 1.3 x 107. 1.3 x105. and 1.3 x 105 conidia.
For each soil type and the no soil treatment. two dishes with 10 pupae per dish were
treated with each concentration of inoculum. Pupae in two additional dishes per soil type

were treated with two 3-ui drops of distilled water. as a control.

155

After inoculation. the pupae were immediately covered with 50 g of the same soil
type. The pupae in petri dishes without soil were left uncovered. Containers were
covered with an air-tight lid and held at 22-23°c. and checked daily for 7 days for
emergence of CPB adults. When adult beetles emerged. they were surface-sterilized in a
0.1% solution of Zephran Chloride®. and transferred individually to 10-cm-diameter
petri dishes with water-saturated filter paper and greenhouse-grown potato foliage.
After 7 days the soil in the dishes was sifted to determine the fate of unemerged
individuals. Those individual found alive were transferred to petri dishes with food. and
all remaining beetles were monitored for an additional three days. Adult beetles were fed
and their dishes cleaned as necessary. Dead individuals were kept moist for a minimum
of two days to check for signs of B. bassiana sporulation.

This experiment was repeated with one container of each soil type per B. bassiana
concentration and10 pupae per container. The dosages applied were 4.2 x105. 4.2 x
104. 4.2 x 103. and 0 conidia per pupa.

Pupai mortality data were corrected for control mortality using Abbott's iorrnuia
(Busvine 1971). A two-way analysis of variance (SAS institute 1985) was performed
to detect significant differences in corrected percentage mortality between soil types and
concentrations. Also, a two-way analysis of variance was performed to detect significant
differences in B. bassiana sporulation on dead pupae between soil types and conidiai
concentrations. Log-probit regressions of dose-mortality were calculated for each soil
type (SAS institute 1985). and the resulting estimated LDso values were regressed on
the fungistasis levels (glucose concentration necessary for 50% germination) to

determine the functional relationship between these two variables.

RESULTS
Soil Characteristics. The characteristics of the four soils collected in 1987

are given in Table 1. The texture of the two Rhode island soils was very similar. but

156

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157

they differed in pH. organic matter and organic carbon contents. The texture of the
Michigan soils differed considerably from each other and from the Rhode Island soils.
The Montcalm soil was much sandier than the other soils, and the KBS soil had a higher
clay content. Organic matter content and pH of the Michigan soils were similar. but
differed from the Rhode island soils. Organic matter content was higher in the Rhode
Island soils. and the soil pH was lowest in one of the Rhode Island soils. The moisture
characteristic curves for the different soils are given In Figure 1. These curves were
used to standardize the water potential in the sells for the dose-mortality study.

Funglstesls Assay. The log~probit regressions of B. bassiana germination
percentages in the fungistasis experiments are presented In Figure 2a.b. The equation
coefficients. mean percentage germination across all concentrations. and the glucose
concentration necessary for 50% germination for each soil type are given in Table 2.
There was a significant difference In fungistasis levels between soils collected In 1986
(F5329) - 27.43. P - 0.0001). Mean conidiai germination was significantly less in
both Michigan soils than in the Rhode Island soils. Germination also differed
significantly between the Rhode Island soils In 1986. with the highest germination
lewls in the Peckham Farm sample. There were no significant differences in
germination levels between the two Michigan soils.

In 1987 there was also a significant soil effect on germination of B. bassiana
conidia «(3,175) - 13.66. P - 0.0001). Mean conidiai germination was significantly
less in the K88 sample than in all other soils tested (Table 2). There was greater
variability in the germination response In the Montcalm soil in 1987 than when
previously tested. Though the glucose concentration necessary for 50% germination In
this soil was higher than that of the RI soils, germination was not significantly different
when compared across all glucose concentrations. A repeated test with a glucose

concentration of 312.5 pg / 9 soil revealed a significant soil effect on germination

158

Figure 1. Moisture characteristics curves for soils used in 1987 fungistasis assays and
Beauveria bassiana dose-mortality study.

159

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162

between all soils. with germination in the Rhode Island soils greater than in the
Michigan soils (Table 3).

There was no significant relationship between fungistasis levels and soil texture.
percentage organic matter. or percentage carbon. However, using data from both years.
there was a significant relationship between soil pH and fungistasis levels (55(15)-
23.32, P - 0.003). Fungistasis increased exponentially as pH increased (Figure 3).

Colloidal chitin stimulated germination of B. bassiana conidia in the absence of
soil. but germination was significantly less than that observed on ground CPB eiytra. In
this first experiment. he percentage conidial germination (mean :t: S.E.) was 26.6 :1: 4.5
on colloidal chitin. 53.9 :t 2.4 on CPB eiytra. and 5.1 t 1.8 on the control. There was
no chitin concentration effect on conidial germination (Fl3.7) - 0.31. P - 0.82) in the
second chitin experiment; however. there was a significant soil effect (Fug) - 145.70.
P - 0.0001). Mean (:t 8.8.) percentage conidial germination on chitin was 44.6 :t:
0.03 without soil, but only 1.3 :l: 0.005 on soil. Ninety-nine percent of the B. bassiana
conidia germinated on the SMA control. in the third experiment. in which conidial
germination was compared on colloidal chitin in the presence of four different soils. no
conidia germinated in any of the soil treatments. In the absence of soil, mean (:t: S.E.)
conidial germination on colloidal chitin was 40.6 d: 14.8. and on SMA was 99.0.

Dose-mortalllty Study. Modalities of CPB pupae incubated in the different '
soils. resulting from inoculation with differing concentrations of B. bassiana, are given
in Table 4. There was a significant dosage effect on CPB pupal mortality (F(4,2o) -
15.95, P - 0.0001). but no significant soil effect. and no significant soil X dosage
interaction effect in the dose-mortality study with the four soils. There were
significant dosage and soil effects on B. bassiana sporulation in dead pupae (for dosage:
F530) - 63.78. P - 0.0001; for soil: F(4,3o) - 3.43. P - 0.02, and for dosage X soil:
F(2o,3o) - 1.94. P - 0.049) (Tables 5 and 6). Over all dosages. fewer individuals
sporulated in the Michigan soils than those in the Rhode Island soils. Regressing the

163

Table 3. Germination of Beauveria bassiana conidia in
Rhode island and Michigan soils with 312.5 ug glucose per

 

 

g of soil. 1987.
% Germination
Soil (mean :t S.E)
R.i. - Peckham Farm 61.7 1 2.05
R.I. - Agronomy Farm 49.2 1 5.44
Mich. - Kellogg Biological Station 3.3 1 1.25

Mich. - Montcalm Research Farm

19.6 .+_ 3.62

 

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166

Table 5. Sporulation ot Beauveria bassiana on CPB
prepupae inoculated with different concentrations of
conidia averaged over all soils and replications (n - 10
individuals per replication).

 

Mean number oi

 

Conidia per pupa pupae sporulating
1 o7 8.1
106 6.1
105 1 .2
104 0.8
103 0.6

O 0.3

 

167

Table 6. Sporulation oi Beauveria bassiana In inoculated
CPB pupae in Rhode Island and Michigan soils averaged
over all dosages and replications (n - 10 individuals I
replication).

 

 

No. oi pupae

Soil with spores
R.I. - Peckham Farm 3.1
R.i. - Agronomy Farm 4.1
Mich. - Kellogg Biological Station 2.3

Mich. - Montcalm Research Farm 2.3

 

 

168

estimated L050 values for B. bassiana mortality in each of the soils with the fungistasis
levels revealed a significant relationship (Fug) - 11.55. P - 0.077). As the

fungistasis levels increased. the L050 values increased at a decreasing rate (Figure 4).

DISCUSSION

8. bassiana fungistasis levels were lower in the soils from Rhode Island than In
those from Michigan in both years tested. and fungistasis was higher in the Montcalm.
Michigan soil in 1986 than 1987. The differences in fungistasis were correlated with
differences in soil pH between sites and years. but not with other soil characteristics
measured. which included soil texture. percentage organic matter. and percentage
carbon. Sharapov and Kalvish (1984) found fungistasis levels for B. bassiana to vary
between soils. with increasing fungistasis corresponding to Increased organic matter
. content. They also found fungistasis to vary with the seasons. with the greatest
inhibition of B. bassiana germination in soils collected in the summer. and the least In
soils collected in the winter. However. they did not report the pH of the soils. Other
researches have shown increases in fungistasis of B. bassiana conidia In soils higher In
organic matter, either from soils collected from different depths (Clark 1969). or with
the addition of organic amendments (Lingg and Donaldson 1981). Fungistatlc effects on
soil-borne plant pathogens are expressed most strongly in neutral or slightly acid soils
(Lockwood 1977). possibly due to reduced competition from soil bacteria and
actinomycetes which generally grow best at neutral pH. and are less tolerant of acid
conditions than fungi (Gray and Williams 1971). Wartenberg and Freund (1962)
implicated actinomycetes and possin other bacteria as inhibitory agents to B. bassiana
germination in soil. 8. bassiana conidia are extremely small (2.4 pm). and Woods and
Grula (1984) and Hunt at al. (1984) have both demonstrated the importance of
exogenous nutrients on the surface of insect hosts in the stimulation of conidial

germination. Natural soils are energy poor environments for the abundance of microbes

169

 

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170

inhabiting them (Lockwood and Filonow 1981). in this study. as in others. the ability to
counter fungistatic effects with the addition of nutrients would suggest that nutrient
deprivation due to intense competition for limited resources in the soil environment
(Lockwood 1977) limits 8. bassiana conidial germination. Lingg and Donaldson (1981)
found that the common soil fungus Pencillium urticae grown in culture produced a water
soluble inhibitor to B. bassiana, but they provided no direct evidence for the production
or action of this inhibitor on germination of conidia in soil.

It is unknown whether pH may have a direct effect on germination of B. bassiana
conidia. Although the fungus is routinely cultured in media at neutral pH. Saminakova et
al. (1981) report maximum sporulation of the fungus at a pH of 5. It is not ruled out
that differences in fungistasis levels between soils are due to the direct effect of pH on B.
bassiana germination.

Colloidal chitin did not prove to be an effective amendment for quantifying
fungistatis against 8. bassiana in soils. In the absence of soil. colloidal chitin did not
stimulate germination of B. bassiana conidia as readily as ground CPB eiytra. Smith and
Grula (1983) examined the response of B. bassiana conidia to different iorrns of chitin.
and found that crude forms of powdered commercial chitin contain large amounts of
protein which Is removed in the preparation of colloidal chitin. These proteins
stimulate germination of B. bassiana conidia. inducing the synthesis of chitinase. Woods
and Grula (1983) reported that nutrients present on the surface of Helicmus zea larvae
are sufficient for the germination and limited growth of infecting conidia. suggesting that
in the natural process of infection. other exogenous energy sources would be more
readily available to the fungus than the purified chitin macromolecuie. That colloidal
chitin was not stimulatory to conidial germination in the presence of soil suggests that
other organisms in the soil may out-compete the fungus for this energy source. and may
produce substances. such as ammonium. that could build up within the petri dish and
inhibit the fungus.

171

Researchers have suggested that the fungistatic effects of soil on B. bassiana
conidia are overcome by the introduction of Insect hosts in the soil (Wartenburg and
Freud 1961. Clerk 1969). Although we could not detect significant differences in CPB
pupal mortality between soils over the range of B. bassiana inoculum tested. a
significant trend of higher L050 values with increased fungistasis levels in the soils was
seen. This would suggest that more highly fungistatic soils would require higher
concentrations of B. bassiana Inoculum for a level of control equivalent to that in soils
with lower fungistasis. Isakeit and Lockwood (1986) compared fungistasis levels with
disease incidence for two plant pathogens. Fusarfum cxysporum f. sp. chopersicl and F.
oxyspcrum f. sp. conglutinans , and found an Inverse relationship between disease
incidence and fungistasis for F. oxysporum f. sp. chopersici. but did not show a direct
relationship with the other pathogen. However. our study demonstrated a significant
relationship between fungistasis and disease by B. bassiana. This relationship warrants
further investigation if pest management practices incorporating B. bassiana
treatments are to be developed.

The decreased number of sporulating pupae In the Michigan soils compared with
the Rhode Island soils may represent greater activity by secondary invading organisms
in the Michigan soils suppressing B. bassiana development in infected individuals.
Although B. bassiana is known to produce antbiotlcs that can suppress the growth of
common saprcphytes (Walstad et al. 1970). some inoculated Individuals appeared to
succumb to bacterial infection rather than to B. bassiana. The proportion of sporulating
individuals among those that died was least at the lower inoculum concentrations and
greatest at inoculum concentrations of 106 and 107 conidia per CPB. Regardless of the
mechanism responsible for the decreased sporulation In the Michigan soils. It would
result in lower populations of B. bassiana conidia in these soils. After monitoring the
natural mortality of the CPB in these soils in Rhode island and Michigan for three years.
Groden (1988) found no mortality due to B. bassiana in Michigan CPB populations.

172

whereas it was a major source of mortality in Rhode island populations. Although
cflfferences in endemic disease levels in Michigan and Rhode Island soils are usually
attributed to climatic conditions. this study suggests that differences between the
fungistatic capacities of the soils may also influence the ecology of B. bassiana in the two

regions.

173

LITERATURE CITED

Bellharz, V.C. and D.G. Parbery. 1982. Dodine: a selective agent for certain soil
fungi. Trans. Br. mycoi. Soc. 79: 507-511.

Busvine, J.R. 1971. A critical review of the techniques for testing insecticides.
Commonwealth Agricultural Bureaux. Farnham Royal, Slough, SL2 aBN England.

Clerk, G.C. 1969. Influence of soil extracts on the germination of conidia of the fungi
Beauveria bassiana and Paecilomyces farlnosus. J. lnvertebr. Pathol.. 13: 120-
124.

Gray, T.R.G. and S.T. Williams. 1971. Soil Micro-organisms. Oliver and Boyd,
Edinburgh. 240pp.

Hunt, D.W.A., J.H. Borden, and J.E. Rshs. 1984. Nutlent-mediated germination
of Beauveria bassiana conidia on the Integument of the bark beetle Dendroctonus
pondercsae (Coleoptera:Scclytidae). J. invertebr. Pathol. 44: 304-314.

Isakeit, T. and J.L. Lockwood. 1996. The disease-supporting capability of soils of
different fungistatic capacity. Canad. J. Plant Pathol. 8: 289-296.

Lingg, A.J. and M.D. Donaldson. 1981. Blotic and abiotic factors affecting
stability of B. bassiana conidia in soil. J. lnvertebr. Pathol.. 38: 191-200.

Lockwood, J.L. 1977. Fungistasis in soils. Biol. Rev. 52:1-43.

Lockwood, J.L. and A.B. Filonow. 1991. Responses of fungi to nutrient-limiting
conditions and to inhibitory substances in natural habitats, pp. 1-61. In: M.
Alexander [ed.). Advances in microbial ecology. vol. 5. Plenum Publishing Co.

Samsinakovs A. and S. Kslaicvs. 1991. Mass production of Beauveria bassiana
for regulation of Leptlnotarsa decemlineata populations. J. invertebr. Pathol. 38:
169-1 74 .

SAS Institute. 1965. SAS user's guide: statistics. SAS Istitute, Cary. N.C.

174

Shsrspov. V.M. snd T.K. Kalvish. 1994. Effects of soil fungistasis on
zcopathogenic fungi. Mycopathol. 85: 121-128.

Smith, R.J. and EA. Gruls. 1983. Chitlnase Is an inducible enzyme In Beauveria
bassiana. J. invertebr. Pathol., 42: 319-326.

Storey, G.K. and W.A. Gardner. 1987. Vertical movement of commercially
formulated Beauveria bassiana conidia through four Georgia soil types. Environ.
Entomol. 16: 178-181.

Walstad, J.D.. R.F. Anderson, and W.J. Stsmbaugh. 1970. Effects of
Environmental conditions on two species of muscadlne fungi Beauveria bassiana
and Metarrhizium anisopliae). J. invertebr. Pathol.. 16: 221-226.

Wartenberg, H. and K. Freund. 1962.Conservation effect of antibiotic
microorganisms and the conidia of Beauveria bassiana. (Abstr.). Rev. Appl. Mycci..
41: 362.

Woods, S.P. and B.A. Gruls. 1984. Utilizabie surface nutrients on Heliothis zea

available for growth of Beauveria bassiana. J. lnvertebr. Pathol. 43: 259-269.

SUMMARY and CONCLUSIONS

These studies of the natural mortality of the Colorado potato beetle represent the
first steps in the process of‘expioring the potential and developing and integrating
biological control of the CPB into future potato production systems. The comparative
approach of this study enabled us to explore the sources and Impact of natural mortallty
under a variety of conditions. which has lead to insights that may have been obscured by
solely examining mortality in the current conventional potato cropping system.
Contrasting CPB populations in early and late planted potatoes it was observed that In
Isolated late plantings, the colonizing summer adult population was only a fraction of
that observed in early planted potatoes. The timing of emergence of summer adults and
their subsequent colonization of late plantings determined the proportion of the
population that was reproductively active. the length of the oviposition period. and
hence, the egg recruitment into late plantings. Manipulating planting date to reduce the
number of reproductively active colonizing adults may be the most direct way to reduce
CPB populations. .

Evaluating seasonal densities and stage-specific survival for CPB populations was
not possible with methodologies presented to date. Methods were developed In this study
that required estimates of recruitment Into the egg stage and adult emergence. it was
found that estimating densities and survival of small larvae was further complicated by
sampling errors and an increasing survival rate throughout the stage. The sampling
errors were found to be related to density, and predictable. and a exponentially
increasing survival function was applied for estimating density of small larvae. Because
recruitment was not measured directly or could not be estimated for some of the potato
research sites in this study. analysis of key factors in within generation survival was

limited to those sites in which complete estimates of stage-specific survival were

175

176

attainable. These did include plantings from both early and late planted potatoes In both
regions with a range of regional population pressures.

Analysis of key factors in within generation survival of CPB revealed large larval
and pupal survival to be most highly correlated with total survival in all plantings.
When early and late plantings were analyzed Independently. egg survival was found to be
the key factor in early planted potatoes. Although pupal survival was found to be density
dependent. survival increased with Increases in density. (Mortality was inverse
density-dependent.) Parasitism by the tachinid Myiopharius doryphorae appeared was
responsible for the significant variations In pupal survival. but this parasitold did not
respond to changes in host density. M. doryphorae was most abundant in the late season.
and was poorly synchronized with its host populations. Parasitism levels were highest
when hosts became available later in physiological time. Again. manipulating planting
date to manage the phenology of host populations could result in improving the synchrony
of this parasitoid with its host. and its impact on pest suppression.

None of the mortality factors measured in this study explained the variations in
survival of large larvae. it can be speculated that mortality by the fungal pathogen. B.
bassiana . the impact of which is difficult to quantity in larvae. or that by the predator.
L. grandis . whose densities were not adequately monitored throughout most of this study.
may be responsible. There Is no evidence of significant ablotlc sources of mortality of
large CPB larvae.

Although none of the mortality factors measured throughout this study explained
the variations in egg survival over all plantings. analysis of the mandibulate preyed eggs
in the Rhode Island and Michigan plantings In 1987 indicate that predation by L. grandis
was the key factor. 0. maculata densities were not correlated with egg survival. but
they were significantly correlated with survival of their total CPB prey (eggs plus
small larvae) in Rhode Island plantings. Further specific studies of these predators

concurred with these results.

177

L. grandis which led on all immature stages of the CPB over a wide range of
temperatures. consumed more CPB prey than per Individual than any other natural
enemy studied to date. The contributions of this predator to the natural mortality of CPB
may have been overlooked in previous studies due to its primarily nocturnal habits. and
because the signs of egg predation by L. grandis are Indistingulshabie from that of
cannbalizing CPB adults. The use of burlap traps if sampled early In the day proved to
be an effective means of sampling for this predator. L. grandis adults were well
synchronized with both first and second generation prey in the Northeast and
Northcentral regions. with summer adults emerging as second generation CPB eggs are
laid.

L. grandis Is a particularly Interesting natural enemy of the CPB. because not only
do the adults appear to be specific predators of this pest. but the larvae of L. grandls
live as ectoparasitoids on the pupae of the same host. Tethering CPB prepupae proved to
be an effective method of sampling for L. grandis parasitism. and showed that L. grandis
parasitism can account for greater than 50% mortality in first generation CPB pupae.

There are many aspects of the biology of this predator that remain to be explored.
Adults appeared to be long-lived in the field. and though they appear to highly prefer
CPB prey. they will switch to aphids when the former host Is not available. Little is
known of factors influencing L. grandis survival. It was observed that L. grandls adults
do become infected with B. bassiana . The relationship between B. bassiana strains
Infecting CPB and those Infecting the predator should be examined before integration of
these two CPB blocontrol agents Is encouraged.

C. maculata is a polyphagous predator and was found to feed on the eggs and small
larvae of the CPB. This predator was well synchronized with its CPB prey in both early
and late potatoes if Rhode island. but only early potatoes in Michigan. When studying the
dynamics of this predator. it Is necessarily to consider all available prey. It does not
appear to preferentially feed on whids. but as aphids become more abundant on potatoes.

178

their impact on CPB prey declines. C. maculata feeds on many food sources in many
cropping systems. A better understanding of its regional population dynamics and its
movement between crops is necessary before the potential for managing this predator
can be evaluated. A multi-cropplng system may be advantageous In providing continuous
food sources for C. maculata. but highly preferred food sources such as corn pollen could
function to draw the predator away from target pests. These relationships need to be
examined if this predator is to be managed.

B. bassiana has been identified as a prominent source of CPB mortality in Rhode
Island in previous studies. It was evident In the first year of the study that B. bassiana
Infections were much lower in Michigan than Rhode island. As this fungus Is primarily a
soil borne pathogen. aspects of B. bassiana ecology in the Rhode Island and Michigan soils
were compared. The comparisons of fungistasis In soils from the two regions revealed
greater suppression of conidial gerrninatlon in Michigan soils. This was found to be
related to the pH of the soil. and may directly affect the incidence of the disease. That 8.
bassiana inoculated pupae were less likely to sporulate in Michigan than Rhode Island
soils would further add to the lower Incidence of the disease in Michigan CPB
populations.

Soil formulations of B. bassiana are being developed commercially for control of
several insect pests. Including the CPB and the corn rootworm. The relationships
between soil characteristics and the ecology of this pathogen should be further explored
to maximize the effectiveness of this pest control measure.

Although no single natural enemy appears to regulate CPB populations in
commercial potato production. this study has demonstrated that In some situations.
natural mortality can suppress CPB populations In potatoes below economically
damaging levels. Perhaps the more important question from the perspective of CPB pest
management is: what regulates populations of CPB natural enemies? The dyname of
the specific predators and parasitold. L. grands. P. bioculatus. and M. doryphorae may

179

be Influenced by abiotic factors. and natural enemies of their own. That of the general
predators. C. maculata and P. maculiventris . is also likely influenced by the

distribution and abundance of alternate hosts. This next level of Interactions must be
examined to in order to Identify mechanisms for enhancing natural enemy populations

and biological control of the CPB.

APPENDICES

APPENDIX A

Modeling CPB Recruitment

APPENDIX A

Modeling CPB Recruitment

Attempts were made to develop a predictive model for CPB egg recruitment using
multiple regression analysis with X-variabies of adult incidence in physiological time‘
(adult-dd). adult incidence in chronological time (adult-days). and accumulated degree-
days (base 10°C). Recruitment. density. and temperature data collected from Rhode
island and KBS potato plantings in 1985 and 1986. were used for the development and
validation of the model. Although models based on individual plantings were successful
in explaining much of the variation in egg recruitment within a planting (r2 values
were generally very high). when compared between plantings and years. the models
were poor predictors of egg recruitment either by day. week. or generation.

A second approach was taken which involved developing a computer simulation
model of CPB oviposition to predict egg recruitment over a generation. The model-
building software package. STELLA‘D. was used for this purpose. STELLA‘D was
developed by High Performance System. Inc. for use on Apple Computer. lnc.'s Macintosh
computers. STELLA‘D allows one to build models of dynamic systems by diagraming the
conceptual framework of a model. This involves identifying the necessary components of
the model. and defining the direction of flows between these components. Once this is
complete. one can add the quantitative relationships that determine the rate of flows
between components. either with equations. graphs. or tables. The STELLA‘D program
converts these into differential equations which it solves numerically. The user sets the
step-size (dt) of the model. When running the model. one can choose either graphical or
tabular forms for the model output. As with most of the Macintosh software. STELLAQ is
a menu driven program. and the feecback for errors both in the conceptual model
construction and the quantifying of relationships is very precise.

180

181

The STELLA‘D diagram of the CPB oviposition model is presented in Figure A1. The
daily rate of CPB oviposition is defined as a function of adult density and daily degree-day
accumulations (dd):

oviposition - adults/2 ' ((2.21 ' dd) - 4.434).

This linear function was developed from temperature dependent fecundity data presented
by Grison (1950; Figure A2). The d1 of the model equaled one day. and eggs are
accumulated throughout the generation. The adult densities observed in the research
plantings were inputted graphically as a function of accumulated degree-days. and
degree-day accumulations were inputted by day. The models for each planting were run
with colonizing adult densities only. to avoid the complications of a preovlposltion
period. Therefore. models were run to simulate oviposition of a single generation. and
were ended before emergence of the next adult generation. The sex ratio of observed
adults was assumed to be 50:50.

The model was run for plantings in which CPB egg recruitment was measured
directly. or estimated from the density of preyed eggs. These included: the late planting
in 1985 In Rhode Island and both early and late plantings in Rhode Island in 1986 and
1987. early plantings at KBS in 1986 and 1987. and early and late plantings at
Montcalm in 1987. The predicted egg recruitment and the observed or estimated egg
recruitment for each of these plantings are presented In Table A1. The variability In the
accuracy of the oviposition model‘s predictions (underestimating recruitment In some
Instances and overestimating It In others) reveals that there are essential aspects of CPB
dynamics that influence oviposition rates that are not accounted for In this simplistic
model. However. some similarities In the predictions and observations of oviposition In

the field are worth noting.

182

 

Figure Al. Diegrem of StelleO model of CPB ovi position

183

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Table A1. Predicted and observed egg recruitment in Rhode Island and Michigan
potato research plantings, 1985-1986.

 

 

_Eon.BemlitmenL_.
Planting Site Year Observed Predicted natlo1
Early Rhodelsiand 1933 362.3 162.7 0.45
1937 443.0 203.3 0.46
KBS 1 936 59.3 63.7 1.02
1937 234.0 270.2 1.15
Montcalm 1937 434.3 200.0 0.46
Late Rhode lsland 1935 50.7 39.1 1 .76
1936 104.5 46.3 0.45
1937 342 25.2 0.74
Montcalm 1937 336.7 422.6 1.09

 

1Predicted/Observed.

185

We:

As discussed in Manuscript 1, egg recruitment in late planted potatoes Is related to
the time the plot is colonized by CPB adults. because of the relationship between the
timing of emergence of summer adults and the proportion of the population entering
reproductive diapause. It the plot is colonized later by emerging adults. a smaller
proportion of the population is reproductively active and ovipositing. Therefore. to
predict recruitment in the late plantings. the proportion oi the CPB adult population that
is reproductively active must be known. Voss et al. (1988) determined the date after
which emerging adults would be in reproductive diapause for Massachusetts. but
suggests that this date would likely vary between populations in different geographic
regions throughout the CPB's range. This would appear to be the case for Rhode Island
and Michigan. because although first generation beetles generally emerged later in Rhode
Island than Michigan. 3 larger portion of the Michigan population appeared to enter
reproductive diapause. Because this was not monitored directly In this study. It was not
possible to incorporate this relationship Into the oviposition model and predict

recruitments for late plantings.

Emulation:

It is interesting to note that the ratio of predicted to observed egg recruitment in
early planted potatoes is consistent within the Rhode island and Montcalm plantings. but
varies between these and the K88 plantings. Field observations of CPB oviposition
revealed that female beetles lay a considerable number of eggs on weeds in the potato
field. Weed densities. although not sampled directly, were observed to be notioably
higher at the K88 site than the Rhode island or Montcalm sites. A study of oviposition on
weeds at the K88 site (see Appendix C) revealed that about 60% oi the egg masses
oviposited at this site may have been on weeds In the potato ileld. These eggs were not

186

taken into account when estimating egg recruitment in this plot. If the 60% eggs on
weeds is added. the observed egg recruitment in 1986 and 1987 at the K88 site was
149.5 and 585.0 eggs. respectively. With these estimates. the ratio of predicted to
observed in these plantings was 0.46 and 0.46 respectively. consistent with that
observed In the early plantings at the Rhode island and Montcalm sites.

The consistency of the error In the model predictions indicates that whatever factor
or factors influencing the number of eggs oviposited is in direct proportion to
temperature and adult densities which drive the model. The laboratory fecundity study
from which this model was based. may under represent oviposition in the field at a
constant proportion. This study was based on the avg. fecundity per day over the life of
the beetle. with an average longevity of 118 days. Differences in the rate of oviposition
over the life of the females were not reported. Kowalska (1969) did find that the
oviposition rate of overwintered females declined dramatically after 30 to 40 days.
although they continued to oviposit for 110 days. in Kowalska’s study. the avg.
oviposition rate estimated over 110 days was 55% of the avg. estimated over the first
40 days. Egg recruitment observed in the early plantings In this study represent those
eggs oviposited by female beetles within the first 40 days of spring emergence. thus. the
oviposition rate would be expected to be higher than that obselved over a longer period.
As the rates used in the model are based on those observed over the life of the beetle. this
could account for the error In the model's predictions.

This model assumes a constant 50:50 sex ratio throughout the generation. There Is
some indication that the mortality rate of males may be greater than that of females.
which would change the sex ratio of the field population over time. This would also
result in underestimating recruitment with the model.

The consistency of the error In predicted versus observed recruitment over a
range of densities and sites. allows us to incorporate a scaling factor into the model to

correct for this error regardless of its cause. Therefore. the oviposition model with the

187

scaling factor was used to predict egg recruitment in the 1985 early planting in Rhode

Island. and the 1986 early planting in Montcalm.

APPENDIX 8

CPB Oviposition on Weeds

APPENDIX 8.

CPB Oviposition on Weeds

in 1987 at the KBS site. it was observed that a number of CPB egg masses were
oviposited on weeds in the potato field. This was thought to represent a considerable
source of mortality, because first instar larvae emerging from hatching egg masses
cannot feed on these weeds. and are not very efficient at locating their host plant
(Harcourt 1971). Thus a study was Initiated to determine what proportion of the CPB

eggs oviposited in the potato field were oviposited on non-host plants.

MATERIALS AND METHODS

in 1987. two potato research plots at the KBS site were sampled to determine the
proportion' of CPB eggs oviposited on weeds In these two plots. The first plot consisted of
30 x 30 m of Caribe' potatoes planted during the first week of May. The second plot
consisted of 30 x 15 m of Russett Burbank potatoes planted in mid May. Potato seed .
pieces were hand planted ca. 30 cm apart in a row and ca. 90 cm between rows. In both
plots a range of weed densities were maintained with hand weeding and mechanical
cultivation. and no pesticides were applied. The sample unit for this study consisted of a
100 x 90 cm quadrat centered a row of potatoes. Vinthin each quadrat the densities of
potatoes and weeds were recorded and all plants were examined for healthy and preyed
CPB egg masses. The densities of weeds were recorded by the following predominant
weed types: grasses. lambs quarter (Chenopodlum album ). red root pigweed
(Amaranfhus retroflexus ). and others. Others were those weeds found sporadically at
very low densities and included: purslane (Portulaca oleracea ). velvet leaf (Abutllon
theophrastl ). milkweed (Ascleplas syrlaca ) and yarrow (Achilles millefollum ). In
the Caribe' plot. 20 randomly selected samples were taken on May 30. June 6. and June

188

189

17. and In the Russet burbank plot. 25 and 14 samples were taken on June 7 and June
18. respectively.

Analyses of covariance (SAS Institute 1985) were conducted for each week to test
for differences in egg densities by plant type. Plot and plant type density were
covariates. Analyses of covariance were similarly conducted to test for differences in

the arcsin proportion of preyed egg masses.

RESULTS AND DISCUSSION
CPB adults did lay significantly more egg masses on potatoes than any individual

weed type in the samples (T able 81). However. over all weed types, 63 1, 0.04 percent
of the egg masses were oviposited on weeds. The arcsin proportion of eggs on weeds was
regressed with weed density. and though a significant regression resulted. weed density
explained only 33% of the variation in the proportion of eggs on weeds (Figure 81).
The proportion of eggs preyed upon varied from 0 to 0.75. The natural logarithm of egg
masses per plant was regressed with the natural logarithm of preyed egg masses per

plant to determine If differences In predation levels were density dependent. The slope of
the regression was significantly less than unity (slope 1; 8.5. - 0.65 3, 0.05).

indicating that egg predation rates were density dependent. Therefore. the significantly
higher predation levels on potatoes over grasses In the week 1 sample. and pigweed over
grasses In the week 3 sample can be explained by predators response to increased in egg
densities on these plant types. Otherwise. there were no differences in egg predation
between weed hosts and potato.

Visser and Ave (1978) reported that CPB adults respond to ”green-leaf" volItaIes
in long range host finding. As CPB females have frequently been observed ovipositing.
not only on nonhost plants in potatoes. but wooden stakes left in the field. it appears that
their short range host recognition is very poor. it is assumed that egg masses oviposited

on nonhost plants result In 100% mortality of hatching first instars unless the leaves of

190

Table 81 . Comparison of CPB egg densities and the proportion of eggs preyed upon on

potato plants and weeds in potatoes at KBS research plots, 1987.

 

 

Weeds per Ems Proportion of
Week Weed type sample‘ per plant2 eggs preyed2
1 grasses 9.70 1 3.52 0.90a 0.06a
lambs quarter 17.30 1 2.91 1.45a 0.19ab
redroot pigweed 9.20 1 1.23 1.75a 0.323b
other3 0.15 1 0.08 0.203 0.00ab
potato 2.90 1 0.07 5.65b 0.45b
2 grasses 9.09 1 1.45 2.093 0.37a
lambs quarter 26.35 1 5.12 1.50ab 0.34a
redroot pigweed 3.57 1 0.94 1.358b 0.36a
ether3 1.43 1 0.41 0.300 0.41a
potato 3.04 1 0.08 3.70c 0.60a
3 grasses 6.45 1 1.14 0.45a 0.413
lambs quarter 18.42 1 2.90 2.21ab 0.63a
redroot pigweed 5.15 1 1.19 2.45b 0.75b
other3 121 1 0.23 0.303 0.42a
potato 2.94 1 0.16 3.94bc 0.50a

 

1Mean 1 S.E. per 100 x 90 cm quadrat centered over a row of potatoes.

2Values followed by the same letter are not significantly different with LS means test
(SAS Institute 1985) at p-0.05 corrected for the number of comparisons (Jones
1985).

3Other includes purslane, velvet leaf. miikweed, and yarrow.

191

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the nonhost plant touch those of potatoes. (Harcourt (1971) reported that small larvae
are unsuccessful at reestablishing themselves on their host plant once they are knocked
off.) The evidence Indicates that CPB egg predators are just as likely to search nonhost
plants as potatoes for prey, so predation is not avoided by oviposition on weeds. This
seemly maladaptive behavior may provide potential for managing early season weeds or

ground cover in potatoes to increase CPB mortality.

APPENDIX C

Densities of CBP Llfestages and Predators at
Research Sites in Rhode Island and Michigan, 1985-1987

193

 

 

 

 

 

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BIBLIOGRAPHY

BIBLIOGRAPHY

Altieri. MA. and w.H. Whitcomb. 1979. Predaceous and herbivorous arthropods
associated with Mexican tea in north Florida. Florida Entomol. 62: 175-82.

Altieri. MA. and w.H. Whitcomb. 1980. Predaceous and herbivorous arthropods
associated with camphorweed (Heferotheca subaxlllaris Lamb.) in north Florida.
J. Georgia Entomol. Soc. 15: 290-99.

Bartholomal. c.w. 1954. Predation of European corn borer eggs by arthropods. J.
' Econ. Entomol. 47: 295-299.

Baskerviiie, SJ. and P. Emin. 1965. Rapid estimation of heat accumulation from
maximum and minimum temperatures. Ecology 50: 514-517.

Beavers. J.B.. c.w. McCoy. and D.T. Kapian. 1983. Natural enemies of subterranean
Diaprepes abbrevlafus (Coleoptera: Curculionldae) larvae in Florida. USA.
Environ. Entomol. 12: 840-843.

Beilharz. V.C. and 0.6. Pasberg. 1982. Dodine: a selective agent for certain soil fungi.
Trans. Br. Mycol. Soc. 79: 507-511.

Bethune. C.J.S. 1872. Report of the Entomological Society of Ontario for the year
1871. Hunter. Rose and 00.: Toronto. 75 pp.

Bethune. C.J.S. 1911. Predaceous bugs. Can. Entomol. 43: 320.

Bjegovic. P. 1971. The natural enemies of the Colorado potato beetle (Lepitinotarsa
decemlineata Say) and an attempt of its biological control in Yugoslavia. Zast.
Bilja 21: 97-111.

Boiteau. G. 1984. Effect of planting date. plant spacing and weed cover on populations of
insects. arachnids, and entomophthoran fungi in potato fields. Environ. Entomol.
13: 751-756.

Bolteau. G. 1986. Effect of planting date and plant spacing on field colonization by
Colorado potato beetles. Leptlnotarsa decemllneata ($83!). in New Brunswick.
Environ. Entomol. 15(2): 311-315.

Britton. W.E. 1914. Some common lady beetles of Conneticut. Conn. Agric. Expt. Sta.
Bull. 181: 21-22.

Bruneteau. J. 1937. Recherches sur les ennemies naturals du Doryphore en Amerlque.
Ann. Epiphyties et Phytogenetique 3: 113-135.

211

212

Burkot, TR. and OM. Benjamin. 1979. The biology and ecology of the cottonwood leaf
beetle. Chrysomela scripta (Coleoptera: Chrysomelidae), on-tissue cultured
hybrid Algeiros (Populus x euramericana) subclones in Wisconsin. Can.
Entomol. 111: 551-56.

Caprio. MA. 1987. Flight initiation behavior and host plant attraction in the Colorado
potato beetle. Leptinotarsa decemllneafa (Say) (Coleoptera: Chrysomelidae).
MS. Thesis. Michigan State University, East Lansing. Mi.

Cartwright. 8.. RD. Eikenburg, and c.w. Angaiet. 1982. Parasitism by Perilltus
cocaine/lac (Hymenoptera Braconidae) of indigenous coccinellid hosts and the
introduced Cocaine/Ia septempunctata Coleoptera: coccinellidae) with notes on
winter mortality. Entomophaga 27: 237-244.

Casagrande. R.A. 1975. An approach to alfalfa weevil management in Michigan. MS.
Thesis. Michigan State University. East Lansing, MI.

Casagrande. R.A. 1985. The “laws" potato beetle, its discovery and spread to potatoes.
Entomol. Soc. Am. Bull. 31(2): 27-29.

Casagrande. R.A. 1987. The Colorado potato beetle: 125 years of mismanagement.
Entomol. Soc. Am. Bull. 33(3): 142-150.

Chamboussou. F. 1938. Remarques sur Lebia grandls Hentz. Rev. Zool. Agr. 37: 165-
1 71 .

Chamboussou. F. 1939. Contribution a l'etude biologique de Lebia grandls Hentz.
predateur americain du Doryphore. Ann. Epiphyties et Phytogenetique 5(3):
387-433.

Clark. R.A. 1980. Use of Beauveria bassiana in potato pest management. MS. Thesis.
Univ. of Rhode island, Kingston. RI.

Clerk, 6.0. 1969. influence of soil extracts on the germination of conidia of fungi
Beauveria basslara and Paealomyces farinosus. J. invertebr. Pathol. 13: 120-
124.

Clerk. 6.0. and M.F. Madelin. 1965. The longevity of conidia of three insect parasitizlng
Hyphomycetes. Trans. Brit. Mycol. Soc. 48: 193-209.

Conrad. MS. 1959. The spotted lady beetle. Coleomegilla maculata DeGeer. as a
predator of European corn borer eggs. J. Econ. Entomol. 52(5): 843-847.

Cooke. R. 1977. The biology of symbiotic fungi. John Wiley and Sons. London.

Couturier, A. 1938. Contribution :3: Mode biologique de Podisus macuieventris Say

predateur americain de doryphore. Ann. Epiphyties Phytogenetique (N.S.) 4:
95-165.

Doberski. J.W. and T.i-l. Tribe. 1980. isolation of entomogenous fungi from elm bark
and soil with reference to ecology of Beauveria bassiana and Metarhizium
anisopliae (Scolytus scolytus F.. the main vector of Dutch elm disease). Trans.
Brit. Mycol. Soc. 74: 95-100.

213

Dover. M.J. and B.A. Croft. 1986. Pesticide resistance and public policy. Bio. Sci. 36:
78-85.

Dowd. P.F. and LT. Kok. 1983. Microorganisms isolated from Rhinocyllus comicus. a
weevil introduced into ngnia. USA. for thistle control. VA J. Sc. 34: 11-13.

Drummond. F.A.. R.L. James. R.A. Casagrande. H. Faubert. 1984. The development and
survival of Podisus maculaventris (Say). a predator of the Colorado potato beetle
(Coleoptera: Chrysomelidae). Environ. Entomol. 13: 1283-1286.

Drummond. F.A.. E. Groden. and RA. Casagrande. 1987. Biology of Oplomus dichrons
(H.S.) and its potential to control the Colorado potato beetle. Environ. Entomol.
16: 633-638.

Drummond. F.A., Yok Suhaya. and E. Groden. 1966. Predation of the Colorado potato
beetle. Leptlnotarsa decemlineata (Say). by Phalangium opillo (L). J. Econ.
Entomol. (in press).

Ewert. MA. and i-i.C. Chiang. 1966. Dispersal of three species of coccinellids in corn
fields. Can. Entomol. 98: 999-1003.

Ferro. D.N. and R.i-i. Voss (eds.). 1985. Proceedings at the symposium on the Colorado
potato beetle. XVii international Congress of Entomol. Mass. Ag. Exp. Stn. Bull.
704. Amherst. MA.

Ferron. P. 1978. Biological control of insect pests by entomogenous fungi. Ann. Rev.
Ent. 23: 409-422.

Ferron, P. 1981. Pest control by the fungi Beauveria. pp. 465-482. In: H.D. Burges
(ed.) Microbial control of pests and plant diseases 1970-1980. Academic
Press. London. 949 pp.

Forgash. A.J. 1985. Insecticide resistance in the Colorado potato beetle. 1n: Ferro,
D.N. and R. Hurley Voss (eds.) Proceedings of the symposium on the Colorado
potato beetle. XVII lntemationai Congress of Entomol. Mass. Agr. Exp. Stn. Res.
Bull. 704. Amherst. MA.

Franz. J. 1957. Beobachtungen uber die naturiiche Sterbiichkelt des Kartoffelkafers
(Leptlnotarsa decemiineata Say) in Kanada. Entomophaga 2: 197-212.

Gauthier, N.L.. R.N. Hofmaster, and M. Semel. 1981. History of Colorado potato beetle
control. pp. 13-33. in: Lashomb. J.H. and R.A. Casagrande (eds.) Advances in
potato pest management. Hutchinson Ross Publishing Co.

Georghion. G.P. 1983. Management of resistance in arthropods. pp. 769-792. in:
Georghion. S.P. and T. Salto (eds.) Pest resistance to pesticides. Plenum Press.
New York.

Gordon. R. 1985. North American Coccinellidae. J. N.Y. Entomol. Soc. 93: 1-912.

Gottwald. TR and W.L. Tedders. 1982. Studies of conidia release by the entomogenous
fungi Beauveria bassiana and Metarhlzium anisopllae (Deuteromycotina:

214

Hyphomycetes) from adult pecan weevil (Coleoptera: Curculionldae) cadavers.
Environ. Entomol. 11: 1274-1279.

Gray. T.R.G. and S.T. Williams. 1971. Soil micro-organisms. Oliver and Boyd.
Edinburgh. 240 pp.

Grison. P. 1950. Influence de is temperature sur i'activlte du Doryphore (Leptinofarsa
decemlineata Say) au stage imaginai. Verb. 6. lntemat. Entom. Kongr. Stockholm
1948: 226-234.

Groden, E. and R.A. Casagrande. 1986. Population dynamics of the Colorado potato
beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). on Solanum
berthaultii. J. Econ. Entomol. 79: 91-97.

Harcourt. D.G. 1963. Population dynamics of Leptlnotarsa decemlineata Say in Eastern
Ontario. i. Spatial pattern and transformation of field counts. Can. Entomol. 95:
613-820.

Harcourt. D.G. 1964. Population dynamics of Leptlnotarsa decemlineata (Say) in
Eastern Ontario. ll. Population and mortality estimation during six age
intervals. Can. Entomol. 96: 1190-1198.

Harcourt. DB. 1971. Population dynamics of Leptinotarsa decemlineata (Say) in
Eastern Ontario. Iii. Major population processes. Can. Entomol. 103: 1049-
1061.

Helgesen. R.B. and D.L. Haynes. 1972. Population dynamics of the cereal leaf beetle.
Oulema melancpus (Coleoptera: Chrysomelidae): A model for age specific
mortality. Can. Entomol. 104: 797-814.

Hodek. i. 1973. Biology of the Cocclnellidae. Academia Press. Prague.

Howard. N.C. and B.L. Landis. 1936. Parasites and predators of the Mexican bean beetle
in the United States. USDA Ciro. 418: 1-12.

lwao. S. and W.G. Wellington. 1970. The influence of behavioral differences among tent
caterpillar larvae on predation by a pentatomid bug. Can. J. Zool. 48: 896-896.

Humber. R.A. 1986. ARS Entomopathogenlc fungal cultures. Boyce Thompson Institute,
ithaca, NY.

Hunt. D.W.A.. J.l-i. Borden. and J.E. Rahe. 1984. Nutrient-mediated germination of
Benuveria bassiana condia on the integument of the bark beetle Dendroctonus
ponderosae (Coleoptera: Scolytidae). J. invertebr. Pathol. 44: 304-314.

ignoffo. C.M., C. Garcia. M. Krohn. T.C. Couch. 1982. Use of larvae of Trichiplusia ni to
bioassay conidia of Beauveria bassiana (cabbage looper). J. Econ. Entomol. 75:
275-276.

Isakeit. T. and J.L. Lockwood. 1966. The disease-supporting capability of soils of
different fungistatic capacity. Canad. J. Plant Pathol. 8: 269-296.

Jeremy. T. 1980. The introduction of Peril/us bioculatus into Europe to control the
Colorado potato beetle. EPPO Bull. 10: 475-479.

215

Johnson. J.A.. I.M. Hall. and K.Y. Arakawa. 1984. Epizootiology of Eryn/a phyfonom:
(Zygomycetes: Entomophthorales) and Beauveria bassiana (Deuteromycetes:
Moniliales) parasitizlng the Dgyptian alfalfa weevil (Coleoptera: Curculionidae)
in Southern Caiifomia. Environ. Entomol. 13: 95-99.

Karg. J. 1968. The influence of shelter belts on the distribution and mortality of
Colorado potato beetle (Lepfinotarsa decemllneata Say).

Karg. J. and T. Mazur. 1969. Participation of amphibians in the natural reduction of
the Colorado potato beetle (Lepflnofarsa decemllneata Say). Ekol. Poi. A.
17(31): 1-531.

Kelleher. J.S. 1960. Ufe history and ecology of Doryphorophaga doryphorae (Riley). a
tachnld parasite of the Colorado potato beetle. Ph.D. Thesis. University of
Minnesota. 70 pp.

Kelleher. J.S. 1966. The parasite Doryphoraphaga doryphorae (Piptera: Tachinidae) in
relation to populations of the Colorado potato beetle In Manitoba. Ann. Entomol.
Soc. Am. 59: 1059-1061.

Knight, H.H. 1923. Studies on the life-history and biology of Perillus bioculatus
Fabricius. including observations on the nature of the colour pattern
(Heteroptera: Pentatomidae). 19th Rep. Minnesota State Entomol. 1921-1922:
50-96.

Kowalska. T. 1969. Fecundity of the Colorado potato beetle (Lepflnotarsa decemilneata
Say) in relation to ecological factors. Ekol. Poi. A. 17(10): 167-182.

Lampert. E.P. and D.L. Haynes. 1965. Population dynamics of the cereal leaf beetle,
Oulema melancpus (Coleoptera: Chrysomelidae). at low population densities.
Environ. Entomol. 14(1): 74-79.

Landis, B..l. 1937. Insect hosts and nymphal development of Podisus maculaventrls Say
and PerlIIus bioculatus F. (Hemiptera: Pentatomidae). Ohio J. Sci. 37: 252-
259.

Lashomb. J.H. and R.A. Casagrande (eds.). 1981. Advances in potato pest management.
Hutchinson Floss Publishing Co.. Stroudsburg. PA. 286 pp.

Lashomb, J.H. and y.S. Ng. 1984. Colonization by the Colorado potato beetle.
Lepfinotarsa decemllneafa (Coleoptera: Chrysomelidae) in rotated and non-
rotated potato fields. Environ. Entomol. 13: 1352-1356.

Lashomb. T.H.. Y. Ng. G. Ghldia, and E. Green. 1984. Description of spring emergence
by the Colorado potato beetle. Leptfnotarsa decemllneata (Say) (Coleoptera:
Chrysomelidae). in New Jersey. Environ. Entomol. 13: 907-910.

Ungg. A.J. and MD. Donaldson. 1981. Biotic and abiotic factors affecting stability of
Beauveria bassiana conidia In soil. J. invert. Path. 38: 191-200.

Lipra. J.J. 1967. An outline of insect pathology. Trans. by U.S. Department of
Commerce. National Technical Information Service. Springfield. VA. 269 pp.

Lockwood. J.L 1977. Fungistasis In soils. Biol. Rev. 52: 1-43.

216

Lockwood. J.L. and A.B. Filonow. 1961. Responses of fungi to nutrient-limiting
conditions and to inhibitory substances In natural habitats. Adv. Microbioi. Ecol.
5: 1-61.

Logan. F.A. 1981. Estimating and projecting Coiorado potato beetle density and potato
yield loss. pp. 105-117. in: J.H. Lashomb and R.A. Casagrande (eds.). Advances
in potato pest management. Hutchinson Ross Publishing Co. Stroudsburg. PA.
269 pp.

Logan. PA. and RA. Casagrande. 1984. Use of the potato cultivar Caribe In management
of the Coiorado potato beetle. Fifty-Sixth Annual Meeting of the E. Branch of the
Entomol. Soc. of Amer. Hershey. PA. (Abstr.).

Logan. PA. R.A. Casagrande. H.i-i. Faubert. and F.A. Drummond. 1965. Temperature-
dependent development and feeding of immature Coiorado potato beetles.
Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). Environ.
Entomol. 14: 275-283.

Mack. T.P. and Z. Smilowitz. 1978. Diumai. seasonal. and relative abundance of Myzus
persicae (Sulzer) predators. J. N.Y. Entomol. Soc. 86: 305.

Mack. T.P. and Z. Smilowitz. 1980. Development of a green peach aphid natural enemy
sampling procedure. Environ. Entomol. 9: 440-445.

Mack. T.P. and Z. Smilowitz. 1982a. Using temperature-mediated functional response
models to predict the impact of Coleomegilla maculata (DeGeer) adults and third
instar larvae on green peach aphids. Environ. Entomol. 11: 46-52.

Mack. T.P. and Z. Smilowitz. 1982b. CMACSIM. a temperature-dependent predator-
prey model simulating the impact of Coleomegilla maculata (DeGeer) on green
peach aphids on potato plants. Environ. Entomol. 11: 1193-1201.

Mack. T.P.. B.A. Bajusz. E.S. Nolan. and Z. Smilowitz. 1981. Development of a
temperature-mediated functional response equation. Environ. Entomol. 10:
573-579.

Madge. R.B. 1967. A revision of the genus Lebia Latreilie in America north of Mexico
(Coleoptera: Carabldae). Ouaestiones Entomologicae 3: 139-242.

Marrone. P.G.. w.M. Brooks. and R.B. Stinner. 1963. The incidence of tachnid parasites
and pathogens in adult populations of the bean leaf beetle Ceratoma trifurcata
(Coleoptera: Chrysomelidae) in North Carolina. J. GA Entomol. Soc. 18: 363-
370. -

Marsh. H.O. 1913. The striped beet caterpillar. pp. 11-16. m: Papers on insects
affecting vegetables and truck crops. U.S. Bur. Ent. Bull. 127. Pt. iI.

McPherson. J.E. 1962. The Pentatomoidea (Hemiptera) of northeastern North America
with emphasis on the fauna of iiIlnois. Southern Illinois University Press.
Carbondale and Edwardsville. 240 pp.

Mohan. K.S. and GB. PiIIaI. 1982. A selective medium for Isolation of Mefarhlzlum
anisoplfae from cattle dung. Trans. Br. Mycol. Soc. 78: 181-162.

217

Morris. F.R. 1963. The effect of predator age and prey defense on the functional
response of Podlsus maculiventris Say to the density of Hyphantrla curea Drury.
Can. Entomol. 95: 1009-1020.

Morris. F.R. 1963. The dynamics of epidemic spruce budworm populations. Mem. Ent.
Soc. Can. No. 31. 332 pp.

Mukerjl. MK. and E.J. LeRoux. 1969a. A quantitative study of food consumption and
growth of Podisus maculaventrls (Hemiptera: Pentatomidae). Can. Entomol. 101:
387-403.

Mukerjl. MK. and E.J. LeRoux. 1969b. The effect of predator age on the functional
response of Podlsus maculaventris to the prey size of Galleria mellonella. Can.
Entomol. 101: 314-27.

Murphy. H.J. 1983. Performance evaluations of potato clones and varieties in
northeastern states. Maine Ag. Exp. Stn. Bull. 788.

Nash. c.w. 1912. Reports on insects of the year. Forty-second annual report of the
Entomol. Soc. Ontario. 1911. pp. 17-19.

Obrycki. J.J. and M.J. Tauber. 1976. Thermal requirements for development of
Coleomegilla maculata (Coleoptera: Coccinellidae) and Its parasite Perllltus
cocaine/lac (Hymenoptera: Braconidae). Can. Entomol. 110: 407-412.

Obrycki. J.J. and M.J. Tauber. 1979. Seasonal synchrony of the parasite Perlmus
cocinellae and its host Coleomegilla maculata. Environ. Entomol. 8: 400-405.

Obrycki. J.J.. M.J. Tauber. C.A. Tauber. and B. Gollands. 1965. Edovum puttlerl
(Hymeroptera: Enlopidae). an exotic egg parasitoid of the Colorado potato beetle
(Coleoptera: Chrysomelidae): Responses to temperate zone conditions and
resistant potato plants. Environ. Entomol. 14: 46-54.

Pabst. G.S. and P.P. Sikorowskl. 1980. Susceptibility of southern pine beetle
(Dendroctonus frontalls) on oligidic medium to Paecllomyces vfrldls and also
Beauveria bassiana. and Metarhizium anisopiiae (fungi). J. Georgia Entomol.
Soc. 15: 235-240.

Pienkowskl. R.L. 1965. The incidence and effect of egg cannibalism In first-instar
(Coleomegilla maculata Iengl (Coleoptera: Coccinellidae». Ann. Ent. Soc. Amer.
56: 150-153.

Putnam. w.L. 1964. Occurrence and food of some coccinellids in Ontario peach
orchards. Canad. Entomol. 96: 1149-1155.

Quinn. MA. and AA. Hower. 1985. isolation of Beauveria bassiana (Deuteromycotina:
Hyphomycetes) from alfalfa field soil and its effect on adult Sltona hlspldulus
(Coleoptera: Curculionidae). Environ. Entomol. 14: 620-623.

Ramoska. WA. and T. Todd. 1985. Variation in efficacy and viability of Beauveria
bassiana In the chinch bug Blissus Ieucopterus (Hemiptera. Heteroptera:
Lygaeldae) as a result of feeding activity on selected host plants. Environ-
Entomol. 14: 146-148.

218

Riley. C.V. 1869. First annual report on the noxious. beneficial. and other insects of
the state of Missouri. Ellwood Kirbyi. Jefferson City. MO. 162 pp.

Riley. C.V. 1871. Third annual report on the noxious. beneficial. and other Insects of
the state of Missouri. Horace Wilcox. Jefferson City. MO. 1.976 pp.

Riley. C.V. 1672. Fourth annual report of the noxious. beneficial. and other insects of
the state of Missouri. Regan and Edwards. Jefferson City. MO. 115 pp.

Riley. C.V. 1673. Fifth annual report of the noxious. beneficial. and other insects of the
state of Missouri. Regan and Edwards. Jefferson City. MO.

Rivard. I. 1964. Carabid beetles (Coleoptera: Carabidae) from agricultural lands near
Beileviile. Ontario. Can. Entomol. 96: 517-520.

Roberts. o.w.. R.A. LeBrun. and M. Semel. 1981. Control of the Colorado potato beetle
with fungi. pp. 119-137. in: J.H. Lashomb and R.A. Casagrande (eds.).
Advances in potato pest management. Hutchinson Ross Publishing Co..
Strousburg. PA. 288 pp.

SAS institute. 1985. SAS user's guide: statistics. SAS Institute. Cary. NC.

Samsinakova. A. and S. Kalalova. 1981. Mass production of Beauveria bassiana for
regulation of Leptlnotarsa decemllneata populations. J. Inverte. Pathol. 36:
169-174.

Sawyer. A.J. and D.L. Haynes. 1984. On the nature of errors involved In estimating
stage-specific survival rates by Southwood's method for a population with
overlapping stages. Res. Pop. Ecol. 26: 331 -351.

Schemey. F. 1959. Der biologische Wirkungseffekt von Carabiden der Gattung Carabus
auf Kartoffelkafer-iarven. Verh. 4. intern. Pfianzenschutz Kongr. Hamburg
1957. 1: 1035-1038.

Schwartz. 1941. Research and control of the potato beetle. Landw. Jahrb. 90: 203-
206.

Shagov. E.M. 1977a. Preferred temperature of the bug Perlllus. a predator of the
Colorado beetle. Ekologiya 1: 97-99.

Shagov. E.M. 1977b. Photoperiodic reaction of the predatory bug. Perlllus and its
variation. Ekologiya 4: 96-99.

Shagov. E.M. 1977c. Effect of humidity on the predatory bug Perlllus bioculatus.
Ekologiya 6: 95-97.

Shands. W.A. and GM. Simpson. 1972. insect predators for controlling aphids on
potatoes. 2. in small plots with two kinds of barriers. in small fields. or in large
cages. J. Econ. Entomol. 65: 514-8.

Shands. W.A.. e.w. Simpson. and MR. Branson. 1972. insect predators for controlling
aphids on potatoes. 1. in small plots. J. Econ. Entomol. 65: 511-4.

219

Shands. W.A.. G.W. Simpson. and RH. Storch. 1972. Insect predators for controlling
aphids on potatoes. 3. in small plots separated by aluminum flashing stripe-
ooated with a chemical barrier and in small fields. J. Econ. Entomol. 65: 799-
805.

Sharapov. V.M. and T.K. Kalvish. 1984. Effects of soil fungistasis on zoopathogenic
fungi. Mycopath. 85: 121-128.

Smith, BC. 1960. A technique for rearing coccinellid beetles on dry foods. and
influence of various poliens on the development of Coleomegilla maculata Iengl
Timb. (Coleoptera: Coccinellidae). Can. J. Zool. 38: 1047-1049.

Smith. 8.0. 1961. Results of rearing some cocineliid (Coleoptera: Coccinellidae) larvae
on various poliens. Proc. Entomol. Soc. Ont. 91: 270-271.

Smith. B.C. 1965a. Growth and development of cocineliid larvae on dry foods
(Coleoptera: Coccinellidae). Can. Entomol. 97: 760-768.

Smith. B.C. 1965b. Effects of food on the longevity. fecundity. and development of adult
coccinellids (Coleoptera: Coccinellidae). Can. Entomol. 97: 910-919.

Smith. B.C. 1965c. Differences in Anatls mall Auct. and Coleomegilla maculata Iengi
Timberlake to changes in the quality and quantity of the larval food (Coleoptera:
Coccinellidae). Can. Entomol. 97: 1159-1166.

Smith. R.J. and E.A. Grula. 1963. Chltinase Is an inducible enzyme in Beauveria
bassiana. J. invert. Pathol. 42: 319-326.

Smith. R.J.. S. Pekrui. and E.A. Grula. 1981. Requirement for sequential enzymatic
activities for penetration of integument of the corn earworm (Hellothfs zea) (by
the fungus Beauveria bassiana). J. invert. Path. 36: 335-344.

Sorokln. NS. 1981. Ground beetles (Coleoptera. Carabidae) as natural enemies of the
Colorado beetle Leptinotarsa decemllneata Say. Entomol. Rev. 60(2): 44-52.

Stark. E.J. and JD. Haper. 1962. Pupai mortality In forest tent caterpillar
Malacosoma disstrla (Lepldoptera: Laslocampidae) causes and impact on
populations in southwestern Alabama. USA. Environ. Entomol. 11: 1071-1077.

Storey. G.K. and W.A. Gardner. 1987. Vertical movement of commercially formulated
Beauveria bassiana conidia through four Georgia soil types. Environ. Entomol.
16: 178-181.

Tadic. M. 1975. Process of adaptation of autochthonous entomophages of the fall
webworm (Hyphantrla cunea Dr.) in Yugoslavia 1963-1972. Zast. Biija 26:
247-267.

Tamakl. G. 1981. Biological control of potato pests. Quantitative approaches to
biological control. pp. 176-192. in: J.H. Lashomb and R.A. Casagrande (eds.).
Advances in potato pest management. Hutchinson Ross Publishing Co.
Stroudsburg. PA. 269 pp.

220

Tamakl. G. and B.A. Butt. 1976. impact of Perillus bioculatus on the Colorado potato
beetle and plant damage. U.S. Dept. Agric.. Tech. Bull. No. 1561. 11 pp.

Tamakl. G.. R.L. Chauvin. and T. Hsiao. 1982. Rearing Doryphorophaga doryphorae a
tachnid parasite of the Colorado potato beetle. Leptinofarsa decemlineata. U.S.
Dept. Agri. Adv. Agric. Tech. West Ser. 21. 14 pp.

Tamakl. G.. R.L. Chauvin. and A.K. Burditt. Jr. 1963. Field evaluation of
Doryphorophaga doryphorae (Diptera: Tachnidae). a parasite. and Its host the
Colorado potato beetle (Coleoptera: Chrysomelidae). Environ. Entomol. 12: 386-
369.

Thieie. RN. 1977. Carabid beetles in their environments. A study of habitat selection
by adaptations in physiology and behavior. Springer-Veriag. NY. 369 pp.

Toumanoff. C. 1933. Actions des chamignons entomphytes sur la pyraie du mais
(Pyrausta nubllalas Hubner). Ann. parasitol. humalne et comparee. 11: 129-
143.

Tower. w.L. 1906. An investigation of evolution in chrysomeild beetles of the genus
Leptinotarsa. Carnegie Institution. Washington. DC.

Trojan. P. 1968. Egg reduction of the Colorado potato beetle (Leptinotarsa decemlineata
Say) as a hunger-dependent reaction. Ekol. Pol. A. 16(6): 171-163.

Visser. J. H. and D. Ave. 1976. General green leaf volatiles In the olfactory orientation
of the Colorado potato beetle. Ent. Exp. Appl. 24: 538-549.

Voss. R.H.. D.N. Ferro. and J.A. Logan. 1968. Role of reproductive diapause in the
population dynamics of the Colorado potato beetle (Coleoptera: Chrysolmeiidae)
in Western Massachusetts. Environ. Entomol. 17(5): 863-871.

Waddrill. V. and M. Shephard. 1975. A comparison of predation by the pentatomids.
Podlsus maculaventris (Say) and Stiretrus anchorage (F.) on Mexican bean
beetle. Epllachna varlvestis Mulsant. Ann. Entomol. Soc. Amer. 66: 1023-1027.

Walsh. BD. 1665. The new potato bug and its natural history. The Practical Entomol.
1: 1-4.

Walstad. J.D.. R.F. Anderson. and W.J. Stambaugh. 1970. Effects of environmental
conditions on two species of muscardine fungi (Beauveria bassiana and
Metarrhizlum anisopllae). J. Invert. Path. 16: 221-226.

Warren. LC. and M. Tadic. 1967. Biological observations on Coleomegilla maculata and
its role as a predator of the fall webworm. J. Econ. Entomol. 60: 1492-96.

Wasterberg. H. and K. Freud. 1962. Conservation effect of antibiotic microorganisms
and the conidia of Beauveria bassiana. (Abstr.) Rev. Appl. Mycol. 41:362.

Watt. B.A. and R.A. LeBrun. 1964. Soil effects of Beauveria bassiana on pupal
populations of the Colorado potato beetle (Coleoptera: Chrysomelidae). Environ.
Entomol. 13: 15-18.

221

Watt. K.E.F. 1964. Density dependence in population fluctuations. Can. Entomol. 96:
1147-1148.

Wegorek. W. 1959. The Colorado potato beetle (Leptlnotarsa decemllneata Say). Publ.
in 1964 for Net. Sci. Found. and Dept. of Agric. by Carl. Inst. inf. Nauk. Tech. i.
Ekon.. Warsaw. Available from Office of Tech. Serv.. Dept. of Comm..
Washington. 1-105. 246 refs. (English).

Whitcomb. w.H. and K. Bell. 1964. Predaceous insects. spiders and mites of Arkansas
cotton fields. Arkansas Agr. Exp. Stn. Bull. 690.

Whitney. H.S.. D.C. Ritchie. J.H. Border. and A.J. Stock. 1964. The fungus Beauveria
bassiana (Deuteromycotina: Hyphomycetaceae) in the western balsam bark
beetle. Dryocoetes confusus (Coleoptera: Scolytidae). Can. Entomol. 116: 1415-
1424.

Wood. S.P. and E.A. Grula. 1964. Utilizabie surface nutrients on Heliothls zea available
for growth of Beauveria bassiana. J. Invertebr. Pathol. 43: 259-269.

Wright. R.J. 1984. Evaluation of crop rotation for control of the Colorado potato beetle
(Coleoptera: Chrysomelidae) in commercial potato fields on Long island. J. Econ.
Entomol. 77: 1254-1259.

Wright. E.J. and J.E. Laing. 1978. The effects of temperature on development. adult
longevity. and fecundity of Coleomegilla maculata Iengl and its parasite. Perflltus
cocaine/lac. Proc. Entomol. Soc. Ontario 109: 33-47.