STELIDOTA GEMINATA
(COLEOPTERA: NITIDULIDAE):
BIOLOGY AND MEANS OF CONTROL 0N
STRAWBERRIES IN MICHIGAN

Thesis for the Degree of Ph.‘D..
MICHIGAN STATE UNIVERSITY
RICHARD FRANKLYN GERTZ
1968

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Steiidota ggminata (Coleoptera:NitiduIidae):

0443 0735

This is to certify that the

thesis entitled

 

Date

0-169

Biology and Means of Control on
Strawberries in Michigan

presented by

Richard Franklyn Gertz

has been accepted towards fulfillment
of the requirements for

Ph.D. degree in Entomoiogy

(7/ /‘Z A/‘céfzf’

/Major professor

May 14, I968

 

 

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ABSTRACT

STELIDOTA GEMINATA (COLEOPTERA:NITIDULIDAE):
BIOLOGY AND MEANS OF CONTROL ON
STRAWBERRIES IN MICHIGAN

 

BY

Richard Franklyn Gertz

A new pest of strawberries--the strawberry sap beetle, Stelidota
geminata--caused an estimated 2-3 million dollar loss to the Michigan
economy in June 1966. Damage was caused by the feeding of adults and
larvae.

. Mass rearing in the laboratory for biology and control studies
was carried out by culturing beetles in 2-quart, wide-mouth jars.
Mbist peaches were provided as a food source.

Life cycle studies showed that there are 3 larval instars and
completion of development from egg to adult requires an average of
19 days at 75°F. Adult lifespan averaged 127 days; the oviposition
period averaged 101 days; and the average number of eggs per day was
4.3 with a maximum of 16.

Adult beetles fed primarily on the underside of ripe and over-
ripe fruit in contact with the ground. One to several feeding gal-
leries were made in the strawberry fruit depending on the number of
beetles present. The individual galleries coalesced into large

cavities after several hours of feeding. Larvae also fed in the

Richard Franklyn Gertz

interior of the fruit. Host crops of Stelidota gaminata in Berrien

 

Co. were sour and sweet cherry, dewberry, tomato, muskmelon, peach,
pear and apple.

Fermenting molasses ground traps were employed to determine
the site of overwintering and time of migration. Adults overwinter
in the woodlots and thickets around the fruit plantings. When the
mean temperature was above 65°F migration from the woodlots occurred.
The odor of ripe, overripe or decaying strawberries attracted adults
to the strawberry plantings. The peak of migration coincided with
the peak of the strawberry harvest.

Application of spray chemicals on the strawberry foliage and
fruit at rates up to twice the recommended gallonage per acre did not
produce control. Bioassays of 24 chemical compounds showed that the
following were toxic to_§. geminata adults: mevinphos, malathion,
azinphosmethyl, diazinon, naled, parathion, GC-6506, Lannate, Sumithion,
68-13005, Azodrin, Furadan, Imidan, and dieldrin. The other compounds
tested were ineffective.

Outstanding response to a synthetic attractant, Duplicolor
auto primer touch-up paint DP-GM 3 was demonstrated in July 1966.
However, subsequent work in 1966 and 1967 in the laboratory and field
failed to demonstrate exceptional attractant properties of this
material. 1

Adult beetles showed significant response to the following
natural attractants: bran, apple pomace, fermenting molasses, and
fermenting grape juice. Fermenting grape juice and fermenting

molasses were highly attractive. TWO methods of control were developed

Richard Franklyn Gertz
that employed molasses as an attractant. The first method utilized
a bait consisting of corncob-molasses-l.25% azinphosmethyl that was
broadcast over the strawberry fields at a rate of 40 lb/acre. This
bait was applied over a majority of the commercial strawberry acreage
in southwestern Michigan in June 1967 and produced satisfactory con—
trol. The second method of control was the placement of liquid fer-
menting molasses-yeast-insecticide poison bait stations around the
perimeter of the strawberry field to intercept the migration of

adults.

STELIDOTA GEMINATA (COLEOPTERA:NITIDULIDAE):

 

BIOLOGY AND MEANS OF CONTROL ON

STRAWBERRIES IN MICHIGAN

BY

Richard Franklyn Gertz

A THESIS

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

DOCTOR OF PHILOSOPHY

Department of Entomology

1968

ACKNOWLEDGEMENTS

 

The writer wishes to express his gratitude to Dr. A. J. Howitt,
major professor, for suggesting this problem and for giving perceptive
advice and financial support.

Special thanks are due to Dr. Paul H. Wooley and Dr. James Bath
of the Entomology Department for the editing of this manuscript.

I sincerely appreciate the interest, provision of facilities
and financial support given by Dr. Gordon Guyer, Chairman of the
Entomology Department.

I also wish to acknowledge the direction given by Dr. Orlo K.
Jantz, Entomology Department in the synthetic attractant phase of my
study.

Thanks are due to Dr. Dean L. Haynes of the Entomology Depart-
ment for his statistical advice.

Grateful acknowledgment is extended to Dr. James H. Moulton of
the Horticulture Department, guidance committee member, for his in-
terest in this study.

I am indebted to Reudiger C. Hillman, graduate student, for
his assistance in collecting data and to Mt. Richard Stroud of
Chemagro Corporation who assisted in the preparation of the corncob
bait.

I wish to dedicate this thesis to my wife Phyllis whose love,
encouragement and spirituality made the completion of this endeavor

a reality.
ii

TABLE OF CONTENTS

 

INTRODUCTION . . . . . . . . . . . .
LITERATURE REVIEW . . . . . . .
METHODS AND MATERIALS . . . .

Collection of Adults . . . . .
Culturing and Rearing Techniques .
Life Cycle Study Techniques
Fecundity and Longevity . . . . . .
Overwintering Site Studies . . . . .
Migration Study Methods . . . . .

DESCRIPTION OF STAGES . . . . . .

Egg 0 O O O O O O O O O O O O O O O
Larva .. . . . . . . . . . . . .

Pupa O O O O C O I O I 0 O O O O O 0

LIFE HISTORY OBSERVATIONS . .

Egg 0 O O 0 O O O O
Larvae . . . . . . . . . . . .

Prepupa . . . . . . .

Pupa . . . . . . . . . . . . . . . .
Adult . . . . . . . . . . . . . . .
Adult Feeding Habits . . . . . . . .
Host Plants . . . . . . . . . . . .
Overwintering . . . . . . . . . .
Migration . . . . . . . . . . . .

DISCUSSION OF BIOLOGY . . .

CONTROL EXPERIMENTS AND RESULTS
MATERIALS AND METHODS . . . .
CHEMICAL CONTROL . . . . . . . . . .

1966 Field Evaluations . . . . . .
-1966 Laboratory Experiments

1966 Greenhouse Experiments . .
1967 Field Experiments . . . . . .

iii

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25
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43
45

INVESTIGATIONS INVOLVING SYNTHETIC ATTRACTANTS

1966 Field Tests . . . .

. 1966 Laboratory Experiments

NATURAL ATTRACTANTS . . . .

1966 Field Studies . . .

1967 Laboratory Studies

BAI TS O O O O O l O O O C 0
Laboratory Investigations

1967 Field Evaluations .

CONTROL DISCUSSION . . . . . .

S WY 0 C O O O O O O O O 0

LITERATURE CITED . . . . . . .

iv

0

Page
47
47
52
52

52
54

57
57
59
66
69

72

10.

ll.

12.

13.

LIST OF TABLES

Reported hosts of Stelidota geminata . . . . . . . . .

 

The average head capsule width and body length of
the larval instars of Stelidota geminata . . . . . .

 

The duration in days of the egg and immature stages
of Stelidota geminata at 75°F . . . . . . . . .

 

The host plants of Stelidota geminata in Berrien Co.
MiCh. , 1966 and 1967 O O O O O O O O O O O O O O O O

 

The average number of Stelidota geminata adults
collected per attractant trap. Berrien Co.,
Mich. , 1967 C O C O C O O O O O O O O O O O O O O O

 

The migration of Stelidota geminata adults to
fermenting molasses, ground traps. Berrien Co.,
1967 O O C O O O O O O C O C O O O O O O C O O

 

The effect of foliar applied toxicants for the
control of Stelidota geminata adults. Berrien
Co. , 1966 O O O O O O O O O O O O O O O O O O O O O

 

Effect of various treatments applied for control
of Stelidota geminata adults . . . . . . . . . . . .

 

Effectiveness of various insecticide formulations
in the control of Stelidota geminata on straw-
berries. Dominion farm, Berrien Co., 1967 . . . . .

 

Response of Stelidota geminata adults to touch-up
auto paints. Dominion farm, Berrien Co., 1966 . . .

 

Response of Stelidota geminata to fermented grape

 

juice and molasses. Berrien Co., Mich., August 1966 .

Efficiency of various carriers in attracting
Stelidota_geminata adults during a 6 hr
exposure period . . . . . . . . . . . . . . . . . .

 

The response of Stelidota geminata adults to
fruit essences . . . . . . . . . . . . . . . . . . .

 

Page

16

22

27

31

33

41

44

48

50

53

55

55

Table Page

14. Response of Stelidota geminata adults to natural
baits placed in cages O O O O O O O O O O O O O O O O O 56

 

15. Efficiency of insecticide-attractant baits in
protecting strawberry fruit from Stelidota geminata . . 58

 

16. Reduction of Stelidota geminata adult feeding on
strawberry fruit in plots treated with corncob-
molasses baits. Dominion farm, Berrien Co.,
Mich., May 1967 . . . . . . . . . . . . . . . . . . . . 6O

 

17. Response of Stelidota geminata to liquid and dry
bait formulations placed in woodlots. Berrien
COO , meh. , June 1967 O O O O O O O O O O O O O O O O O 62

 

18. Response of Stelidota geminata adults to fermenting
molasses ground traps placed around a 2.5 acre
strawberry field. St. John farm, Berrien Co.,
Mich., June 1967 . . . . . . . . . . . . . . . . . . . . 63

 

19. Response of Stelidota geminata to 5-day old and
fresh molasses + yeast ground traps. Berrien
CO. , Mi-Ch. ’ 1967 O I O O O O O O O O O O O O O O O O O O 65

 

vi

LIST OF FIGURES

Figure Page

1. Migration of Stelidota geminata adults to
fermenting molasses ground traps. Berrien Co.,
M1Ch. , 1967 O O C O C O O O O O O O O O O O I O O O O O 34

 

2. The mean number of Stelidota geminata adults
collected in fermenting molasses ground traps
inx3 woodlots. Berrien Co., Mich., 1967 . . . . . . . . 35

 

3. Residual toxicity of selected insecticides to
Stelidota geminata adults. a, azinphosmethyl;
b, malathion; c, naled; d, mevinphos;
e, diazinon . . . . . . . . . . . . . . . . . . . . . . 46

 

vii

LIST OF PLATES

Plate Page

I. Egg of Stelidota geminata . . . . . . . . . . . . . . . . 18

 

II. Larvae of Stelidota geminata . . . . . . . . . . . . . . l9

 

III. Pupae of Stelidota geminata . . . . . . . . . . . . . . . 20

IV. Adults of Stelidota geminata . . . . . . . . . . . . . . 21

 

V. Damage to strawberry fruit caused by the feeding
of Stelidota geminata adults . . . . . . . . . . . . . 26

VI. Response of Stelidota geminata adults to DP—GM 3
acrylic paint primer. Berrien Co. July 1966 . . . . . 51

 

viii

INTRODUCTION

 

Production of strawberries has been a major horticultural
enterprise in Michigan for over 70 years. Michigan is currently
exceeded only by California, Oregon and Washington in strawberry
production. In the years 1959-63 Michigan growers produced an average
of 37.2 million pounds of strawberries annually with a cash value of
6.3 million dollars. Almost two thirds of the crop is sold on the
fresh fruit market. The strawberry industry is exceeded only by
apples and cherries in dollar volume for fruit enterprises in the
state. Strawberries are horticulturally adaptable for most sections
of the state and are grown commercially in the following counties:
wayne, Kent, Ottawa, Berrien, van Buren, Manistee, Leelanau, Alpena,
and Houghton. Approximately 50% of the 9,440 acres devoted to come
mercial strawberry production is located in Berrien and van Buren
Counties in southwestern Michigan.

In late June 1966, the strawberry harvest in southwestern
Michigan was abruptly terminated because of insect-contaminated fruit.
An epizootic population of a nitidulid beetle, which was uniformly
distributed throughout the area, was determined to be the causal
agent. Approximately two thirds of the crop was not harvested
during the 1966 season. The beetle was later identified by

Dr. Malville H. Hatch of the University of Washington as Stelidota

2

geminata (Say); family Nitidulidae. Stelidota_geminata is commonly

 

referred to as the strawberry sap beetle in Michigan.

The loss to the Michigan economy was estimated at 2-3 million
dollars. In addition, particular hardship was felt by thousands of
migrant harvest workers who were deprived of 2-3 weeks employment at
a time when no other harvest work was available.

Surveys and reports from other strawberry producing areas of
Michigan have shown that the beetle is restricted in distribution to
southwestern Michigan. However, climatic conditions in Michigan are
within those cited in the literature for_§. geminata so that there is
no guarantee that the insect cannot become established in other
regions.

Control of S: geminata is complicated by the following factors:
(1) The adult beetles start migrating into the strawberry plantings
as the fruit begins to ripen. Operating ground spray or dust equip-
ment through the planting at this time results in excessive damage
to the crop. In addition, injured fruit attracts more beetles into
the planting. (2) Plant foliage is at peak density which prevents
proper coverage of the fruit with insecticides. (3) The harvest
season is extended over a.3 week period which involves 5-6 separate
pickings, each picking followed by l—2 inches of irrigation. To be
effective, pesticides would have to be applied after each irrigation.
(4) Irrigation practices during the harvest season limit the use of
ground pesticide application equipment. (5) The type and quantity of
insecticide which can be applied close to or during harvest is re-

stricted by the Food and Drug Administration regulations. As a result,

3
many effective insecticides cannot be used within the ”interval from
last application to harvest" as published in the USDA Pesticide
Summary.

The investigations reported in this thesis were designed to
clarify certain aspects of the biology and control of the strawberry
sap beetle with respect to the production of strawberries in Michigan.
These investigations included studies of: (l) the life cycle, (2)
the fecundity and longevity, (3) the host range, (4) the site and

stage of overwintering, and (5) a method for control of the insect.

LITERATURE REVIEW

 

Very few papers have been published with direct reference to

Stelidota geminata; consequently, much of this review will be de-

 

voted to the genus Stelidota and related genera.
Parsons (1943) stated that the genus Stelidota is comprised
of approximately 40 species and is generally distributed throughout
the world with the exception of continental Africa. Although con—
sidered a tropical genus the three North American species, S. strigosa,

_§. geminata and_§. octomaculata, seem to have a neotropical origin

 

(Parsons 1943).

Parsons characterized Stelidota_geminata as follows:

 

Nitidula geminata Say, 1825, Journ. Acad. Philad., 5, 181.

 

Oval, narrower posteriorly, moderately shining, sparsely
punctate, testaceous to rufo-piceous, elytra with indistinct
pale spots. Head coarsely, densely, shallowly punctate.
Prothorax twice as wide as long, narrower in front, apex
deeply emarginate, base bisinuate, sides regularly arcuate
from base to apex, margin broad, deplanate, hind angles
rectangular, disc moderately convex, surface coarsely, densely
punctate. Elytra slightly broader than the pronotum. Each
elytron with 9 costae each of which has a row of fine punc-
tures, each puncture bearing a short pale hair. Between the
costae are rows of large, shallow punctures. Beneath moder-
ately densely, coarsely punctate. In the male the middle
and posterior tibiae distinctly arcuate, the former suddenly
dilated in its distal half, the latter in the distal third.
Length 2-3 mm.

This species occurs (Feb. 20-Oct. 23) chiefly in the
spring from Massachusetts (Tyngsboro, Springfield) to Florida
(Capron, Haulover, Edgewater, Miami, Paradise Key), west to
Iowa (Mt. Pleasant), Missouri (St. Louis) and Texas (Columbus),
south through Middle America to Colombia and Brazil.

4

5
Hosts from which_§. geminata have been reported are summarized
in Table l. The majority of reported hosts indicate a preference for
overripe or decomposing fruit.
Nitidulid beetles are primarily saprophytic and are not con-

sidered to be economically important. The genus Carpophilus, however,

 

does have several species which are considered economic pests. Species
of this genus invade corn, dates, pineapples and stored products
(Connell 1956). Schmidt (1935) reported that of 6 species of nitidulids

found in Hawaiian pineapple fields, 9, humeralis (F.) and 9, hemipterus

 

(L.) were the most important. He stated that none of the species were
capable of inflicting primary injury or of transmitting disease.

Their primary economic importance was as a nuisance in canneries where
they had to be prevented from getting into the cans. Both species

had a high reproductive potential and a short immature period as com-
pared to length of life of the adult. However, the numbers of 9,

hemipterus and humeralis adults present in the pineapple fields were

 

a result of migration in response to the odors from decaying and
freshly cut pineapple and not their reproductive potential (Schmidt
1935).

Lindgren and Vincent (1953) reported that 4 species of beetles,

Carpophilus dimidatus (F.), 9. hemipteries (L.), Urophorus humeralis

 

 

 

(F.), and Haptoncus luteolus (Er.), infest dates in California. Adult

 

beetles were primarily attracted to fermenting dates on the soil;
these dates resulted from "June drop". Reproduction occurred at these
sites and the adults later infested dates on the trees, being par-

ticularly attracted to any that were rotten. Fumigation of the dates

 

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8
prior to processing at the packing house was the primary means of
control, but applications of a 5% malathion dust to the trees 1-6
weeks before harvest, greatly reduced adult beetle populations.
Connell (1956) in his comprehensive publication of the biology,

taxonomy and control of Carpophilus species also included host

 

materials where S, geminata adults and larvae were collected. He

stated that Carpophilus lugubris Murr. was a primary pest of corn

 

and was of particular concern to the sweet corn industry. He also
reported that chemical control of adults was effective but costly.
Dorsey and Leach (1956) reported that_§. geminata and

Glischrochilus fasciatus (Oliver) were important vectors of oak wilt.

 

This was the only reference to_§. geminata as a economic pest.

METHODS AND MATERIALS

 

Collection of Adults

 

Projected laboratory investigation required large numbers of
adult beetles. Approximately 1,000 beetles were collected from the
cherry orchard and the muskmelon and tomato cull piles on the
Dominion farm, Berrien Co. in August, 1966. Beetles were collected
by transferring infested fruit to a l-pint Plasti-Kan container.
After the beetles left the fruit, the fruit was discarded and the
same procedure was repeated until the desired number of beetles was
collected. Wet paper towels were placed in each container to prevent

desiccation in transit to the laboratory.

Culturing and Rearing Techniques

 

A modification of the technique reported by Connell (1956)
was used in rearing and culturing adult beetles and larvae. TWO-
quart, wide mouth Kraft citrus jars one half filled with moist wood
shavings were used to rear adult beetles. Moist sand was used in
place of the wood shavings for larval and pupal studies. To provide
ventilation and avoid desiccation, a problem experienced by Connell,
2 three-quarter inch holes were bored into each cover and the holes

covered with_32-mesh Saran screen.

10

Several food sources, including apples, cherries, dried peaches
and dried apricots, were investigated for suitability in rearing
adults and larvae. Dried peaches and apricots moistened with water
for several hours were the most satisfactory media tested. Dried
peaches, which were less expensive than apricots, were used as the
primary food source. One half of a moistened peach was placed on a
3X3 inch Saran screen in each adult culture jar, the screen was em-
ployed to prevent adherence of the shavings to the food. The food
was exchanged weekly to transfer the larvae before pupation started
and to prevent excessive wetting of the wood shavings. Each rearing
jar contained approximately 300 adult beetles.

Several hundred larvae in different stages of development were
observed on peaches after 1 week. Infested peaches were transferred
to jars one half filled with sand, which simulated natural conditions
for pupal development. Only 1 layer of fruit was placed on the sand
because several layers of fruit retarded drying and caused excessive
moisture in the sand.

Adult emergence was observed 10-12 days after the day of trans-
fer and continued for approximately 1 week. To lure the adults from
-beneath the fruit and from the soil tunnels, an attractant trap, con-
sisting of a moistened peach in a 1 pint Plasti—Kan, was used. The
newly emerged beetles were then transferred to adult culture jars.
When emergence terminated, the decayed remnants of the peaches were
discarded and the jars were used for the next brood.

The culture jars were placed on a table in the laboratory where
the temperature ranged from 60-80°F,anui the relative humidity from

25- 70700

11

Life Cycle Study Techniques

Lindgren and Vincent (1953) reported that oviposition was

obtained on moist strips of green blotting paper in petri dishes for

 

9, dimidatus, E, hemipterus,_g. numeralis, and_§. luteolus. Eggs
were transferred to petri dishes containing dates and moist sand to
observe further development. Connell (1956) employed 2—quart battery
jars one half filled with sand to investigate the life history,

fecundity and longevity of Carpophilus sp.

 

Small baby food jars with 2 one-quarter inch holes bored in
the top and covered with Saran screen were very satisfactory for the
laboratory investigations of life cycle, fecundity and longevity of
_S. geminata.

In the life cycle study each egg was observed through the
larval and pupal stages. Eggs were obtained by placing 50 beetles in
a rearing jar with moist filter paper and a section of peach. The
filter paper was observed 2-3 times daily for eggs. Eggs were sepa-
rated by cutting the filter paper around each egg with a pair of
scissors and were transferred to a jar containing moistened filter
paper and a small portion of peach. Observations and records on
developmental progress were made 2-3 times daily.

To determine the length of the stadia, head capsule measure-
ments were made with an ocular micrometer in a binocular stereo
microscope. The larvae were observed directly in their jars, hence
disturbance was kept at a minimum. After the second molt, one-

quarter inch of sand was added to each jar as a medium for pupation.

12
After the pupal cell was constructed in the soil, the top layer of
soil was carefully picked away to allow observation of the pupa.
Following observation the opening was covered with a small section of

moist filter paper.

Fecundity and Longevity

 

Considerable difficulty was experienced in separating adult
beetles on morphological characteristics without injuring the speci-
men. To determine the fecundity and longevity of_§. geminata, 15
newly-emerged adults were placed in a rearing jar for an 8-10 day
mating period. When the first eggs were observed, each adult was
placed in a separate jar and egg counts were recorded daily. Jars
in which eggs were observed were labeled, tabulated, and set aside.
After 10 days, beetles in jars which contained no eggs were clas—
sified as males and put in with the females to make 5 pair.

Fecundity was determined by transferring the adults to a new
culture jar every 3 days to circumvent egg hatch because larvae are
more difficult to count than eggs. After transfer, the filter paper
and bottom of the original jar were observed for eggs and the results
recorded.

Longevity studies were conducted using the same beetles as

observed for fecundity.

Overwintering Site Studies

 

Insect control is predicated on a thorough knowledge of the

life cycle. Included in the life cycle is the stage that overwinters

13
and the overwintering site. Several studies were made to determine
these facts.

Random soil samples were collected in October 1966 to ascertain
the presence of_§. geminata in the Dominion strawberry plot and adja-
cent pear orchard. Each sample consisted of l spadeful of soil taken
to a depth of 8 inches. TWelve samples were obtained from beneath
the dry remains of strawberry clusters, and 10 samples were collected
from beneath pears. The soil samples were sifted through a coarse
sieve in the laboratory to reveal the various stages of the insect.

On October 8, 1966, adults and larvae were placed in containers
in the strawberry plot to determine the stage or stages that over-
winter. The containers were 1 quart Plasti-Kan cartons three fourths
filled with sand. A 1 inch layer of straw and one half of an apple
were placed on the sand. Drainage holes were punched in the bottom
of each carton. Adults and larvae were placed in containers as
follows: TWO cartons with 25 newly-emerged adults from laboratory
cultures; 1 carton with 25 adults freshly-collected from beneath
pears; 2 cartons of 25 adults 2 months or more in age from laboratory
cultures; 1 carton with larvae collected from the field; and 2 cartons
with approximately 50 larvae each from laboratory cultures. It was
anticipated that a portion of the larvae would mature and pupate in
the soil and could be used in the study. The cartons were covered
wvith nylon cloth and sunk in the soil so that the tops of the cartons
vaere even with the surface of the ground. On March 28, 1967, the

containers were removed from the soil and taken to the laboratory

14
where the sand was sifted, the trash sorted and the life stages data
recorded.

In laboratory and field tests, discussed in the control sec-
tion, several bait mixtures and compounds were found to have attractant
properties for adult beetles. Effective attractant baits and traps
were set out on April 12, 1967 in the vicinity of woodlots, pear
orchards, peach orchards and strawberry plantings located on the
Dominion, St. John and Swisher farms to determine the overwintering
sites of the adult beetles. Attractants used were moist-bran,
Duplicolor DP-GM3 auto paint primer, mixtures of bran and grape juice,
bran plus 50% raw molasses and liquid molasses plus yeast.

Bran baits were prepared by wetting the bran with liquid until
saturated and adding azinphosmethyl (25% WP) to make a 1% active
azinphosmethyl mixture. The containers for the bran baits were 8
inch square boxes constructed of 1X2 inch boards, with a bottom of
fine mesh screen and a removable top of coarse mesh screen. The con-
tainers were placed on the soil and partially covered with leaves to
reduce the loss of water.

The raw molasses liquid bait was prepared by combining 1 part
by volume raw molasses with 1 part water and yeast suspension (1
package of dry yeast in 1 gal of water). Sufficient azinphosmethyl
(25% WP) was included to make a 1% active azinphosmethyl suspension.
One eighth of a pint of this mixture was put into a 1 pint Plasti-Kan.
A 2 inch hole was cut in the cover and the container was placed on
the ground at a 45° angle. Liquid molasses traps were exchanged every

2 weeks.

15

Paint primer attractant lures were prepared by filling 35 mm
film cans with paint primer and attaching the screw cap cover. Each
cover had 2 one—quarter inch holes. A 3 inch length of one-quarter
inch cord was inserted into one of the holes to serve as a wick. The
cans were fastened 3 ft above the ground on a yellow card that was
attached to a wooden stake. Both sides of the yellow card were
covered with Tanglefoot. The paint was replenished every 5 days.

Bait station performance records were taken at 2 week inter-

vals, during the spring migration period.

Migration Study Methods

 

Fermenting molasses bait stations, as previously described,
were employed to determine the dates of migration for_§. geminata.
The specific location for each trap in the study area is given in
Table 6. The liquid traps were replaced on a weekly schedule during
May and biweekly during June, at which time insect counts were made

for each station.

DESCRIPTION OF STAGES

 

The Egg

Eggs of_§. geminata are milky-white in color and average 0.71 mm
in length by 0.27 mm in width. They are elongate and cylindrical in
shape with rounded ends. The surface of the egg is smooth and is
covered with a moist, adhesive substance. Eggs may be deposited

singly or in clusters of 2-15. See Plate I.

The Larva

The mesothorax, metathorax and the 10 abdominal segments of the
larva are white. The tergum of the prothorax is gray and the head is
light tan with brown mandibles. The body is translucent with the gut
appearing as a dark longitudinal band. There are 3 instars. The
average head capsule width and body length of each instar are given
in Table 2.

TABLE 2.--The average head capsule width and body length of the
larval instars of Stelidota.geminata

 

 

 

 

 

Instar Headczapsule width Body length
First 0.30 mm 1.0 mm
Second 0.48 3.0

Third 0.60 4.5

 

16

l7

Boving and Rozen (1962) described the distinquishing charac-
teristics for the mature larvae of_§. geminata as follows: The
mandibles are not markedly swollen at the base, the apex is bidentate
and only dorsal subapical teeth are present. Lateral spiracular tubes
with spiracles situated at the apex extend from the abdominal segments.
The length of the spiracular tubes on the 8th segment is approximately
equal to their base diameter. Urogomphi are prominent and rise above
the 9th abdominal tergum. They are curved upward, sharp pointed,
apically simple and lack ventral accessory spines. The pregomphi
rise sharply from the 9th abdominal tergum and are moderately long,
their length being more than one-third that of the urogomphi. See

Plate II.

212.3222.

Pupae of S. geminata average 2.2 mm in length. At first the
pupae are white but become light-brown in the later stages of develop-
ment. They are of the exarate type and are not covered by a shell.
Transformation occurs within pupal cells formed at depths of 1-4

inches in the soil. See Plate III.

.mumcwaow moonwaoum mo wwwln.H oumfim

 

l9

.numcfiaow

wooeaouum mo assume--.HH woman

 

.Mumcfiamw muoowfioum mo oma5m1I.HHH madam

 

 

Seesaw 38:65 no BEEISH 32m

 

LIFE HISTORY OBSERVATIONS

 

Elsa

As shown in Table 3, the average length of the egg stage was
2.5 days for 27 eggs. The majority of eggs were deposited on the
underside of the filter paper and on the bottom of the jar. Rarely
were they found on the lid and none were observed on the fruit. All
the eggs were laid on their sides and the majority were clustered in
rows of 3-15. Egg desiccation occurred rapidly when they were exposed
to the air. A study of 50 eggs showed that the percent egg hatch
was 93% under humid conditions.

TABLE 3.--The duration in days of the egg and immature
stages of Stelidota geminata at 75°F

 

 

 

 

 

Instar

Egg 1 2 3 Prepupal Pupal Total time
Average
length 2.5 2.3 1.3 3.6 3.1 6.3 19.1
Range 0.4 0.9 0.7 2.1 1.9 2.5 8.5
No. of
observa- 27 15 13 12 12 ll
tions

 

Larvae

The duration of the 3 larval instars at 75°F is shown in

Table 3. The average time of development for the lst-instar was 2.3

22

23
days for 15 larvae. The duration of the 2nd-instar was the shortest,
averaging 1.3 days for 13 larvae. The 3rd-instar had the longest
time of development with an average of 3.6 days for 12 larvae. The
3rd-instar larvae, upon reaching maturity, were observed to wander
about the jar for approximately 12 hr all the while exhibiting a
curious searching behavior. Connell (1956) also reported this

phenomenon for Carpophilus lugubris. After the searching period,

 

the larvae burrowed into the soil and constructed a cell for pupation.

In laboratory studies the larvae preferred to feed on the
bottom and in the interior of the peach rather than on the top. All
of the instars fed voraciously until just before the molting period,
then they became quiescent.

In the field, larvae were observed to feed within overripe
and decayed strawberries. Large numbers also were observed under
the berries in the juice-soaked trash and soil. In addition, larvae

were observed in'other host crops (Table 4).

Prepupa

The prepupal stage has morphological characteristics similar
to the larva with the exceptions that the body color is milky-white,
not translucent, and is more cylindrical. Initiation of this period
started when the 3rd instar ceased feeding and wandered about the
jar. The criterion used for termination of the period was the
appearance of transformation to the adult. As shown in Table 3 the

mean number of days for 12 prepupae was 3.1.

24
Pupa

The length of the pupal period, as indicated in Table 3, was
found to average 6.3 days for 11 pupae. Pupation usually occurred
in the soil at depths of 1—4 inches; however, it also was observed
on top of the soil under moist trash and to depths of 7 inches in
loose soil. The majority of pupae were found within a 12 inch radius l—a
of the cluster on which the larvae were feeding, indicating a re-

stricted dispersal range for the mature larva.

 

Adult .J
_____. If

Newly-emerged adults are light brown and 2.5 mm in length.
Sexes are not readily distinguishable on the basis of morphological
characteristics. Mating occurs soon after emergence but a pre-
oviposition period of from 8 to 10 days is required before eggs are
laid. Mating is apparently required for continuous oviposition be-
cause females that were isolated from males stopped laying eggs
after several days. These observations support those of Connell
(1956) who reported that mating was frequent and apparently necessary
to initiate and sustain oviposition in E. humeralis. Adults are
shown in Plate IV.

The fecundity study, based on observations of 5 females,
showed the average total number of eggs laid per female to be 437,
with a range of 239. The maximum oviposition period was 125 days
with an average of 101 days. The average number of eggs deposited

per day was 4.3; the maximum was 16 eggs per day. The average

25
lifespan of 10 adults was 127 days with a range of 147 days. The

oviposition period was found to last through most of the adult life.

Adult Feeding'Habits

 

Stelidota geminata adults were observed to be strongly

 

attracted to overripe and partially decayed strawberries. They pre-
fer to feed on berries that touch or are in contact with the ground.
However, when this food supply is depleted they will feed on berries
that do not make contact with the soil. After flying to new food
sources and alighting on the berry, they immediately move to the
underside of the fruit and commence feeding by chewing into the soft
flesh. The typical feeding tunnels made in the fruit are shown on
Plate V. Each injured berry may contain from 1 to 50 beetles. The
number and size of the holes and feeding tunnels is determined by
the number of beetles present in the fruit.

The adultsowill leave infested berries to crawl under the
moist trash where they construct tunnels in the soil. When infested
fruits are disturbed the beetles will disappear into the soil tunnels.
Beetles with no chance of escape will remain motionless and feign

death.

Host Plants

 

After feeding on strawberries, the beetles feed on a succes-
sion of ripening fruits. The host plants, as determined by observa-

tions of infested fruit, are summarized in Table 4. Stelidota geminata

 

was found in approximately 50% of the overripe and decayed tart

.muasom mumcflfiow muoozoum mo mcfivoow ocu mo oomomo mofiuuonsfiwnum 3 ommEmQIIS mung

 

27

 

 

unmocoom H .w:<lom mosh mood
ocmocoom ma mashlmd moon m>um~
ucmocoom mH mfiohln moan ufioom muuonamuum
ucmocsnm mood .om osohlm mash mason madam
coeaoo om .uaowumm .w=< m>um~
cosaoo Hm .uooimm .w=< mason “mom
descammooo mm .udomimm .w:< mood
coaaoo ma .uaomlmm .w=¢ m>HmH
coEEoo om .umomlam .w:< oasom zomom
osmocsom am .w:<|wH .w:< mason aofioaxmaz
ucmocoom mg .w=<um .wo< ufioom moHHa Haao cw moOumaoa
Hmcofimwooo m .w:¢:~ .w:< mason madam cw mucumaoa
:oEEoo om %H:h uaonm muuoozon
uncowmmooo m .w:< mood
amcofimmooo : : o>um~
ucoocsom coma .m .w:<|mm mash oases huuono uooam a udom
oocouudooo vo>uomoo moon ucomoum mowmum uaouu wcwmooon
o>HumHom

 

 

 

.32 Ba 82 3:3: .8 523m 5 aumcasmm «333% no 352 to: mean-..» 53.9

28
cherries on the ground in the Dominion orchard on July 25, 1966.
Beetles were not observed on the fruit in the trees. All stages of
the insect were found, but the immature stages were not as abundant
as they were in the strawberries. Adults and immature stages were
still present on August 9.

On the same date adults, but not larvae, were observed on
fallen dewberries. Beetles were not observed in adjacent raspberry
or blackberry plantings.

A survey of the tomato fields on the Dominion farm made on
August 1, 1966 revealed the presence of adults in tomatoes which had
cracked. Five to seven beetles per tomato were found in 25% of the
tomatoes in the cull piles. By August 9, the infestation was reduced
to 5% of the rotten tomatoes. Although tomato harvesting had been
in progress for 2 weeks, only adults could be found in the cull
piles, usually restricted to feeding in tomatoes on the perimeter of
the piles. By August 18, only a few beetles were found in tomato
fields or cull piles.

Beetles, but no larvae, were observed infesting melons in the
field and in cull piles but the population remained small during the
survey period (August 19, August 29, and September 13).

Peach and pear orchards surrounding the study area were sur-
veyed during August, September and October for the presence of life
stages of_§. geminata. The results are summarized by date:

August 19.

Adults and larvae were abundant on fallen peaches.

29
Adults and larvae were abundant on pears which had
fallen prematurely during pruning for fireblight
control.

September 23.

No adults or larvae found in peaches. A few pupae
were found in the soil under rotten peaches.

An average of 2—3 adults were found per pear. Larvae
were common in fallen fruit.

September 30.

Newly-emerged adults were found under approximately
10% of the peaches.
No adults were observed in the pears.

October 12.

An average of 2 adults per pear, based on a lO-pear
sample.

October 31.

One adult found on 34 randomly sampled fruits.

The host range of_§. geminata, as reported by other workers,
is summarized in Table 1.

Reproduction was not observed under field conditions in musk-
melon and tomato. Laboratory experiments were designed to test the
suitability of tomato, muskmelon, pear and apple as media for the
production of larvae. Numerous larvae were produced in tomato, pear,
peach and muskmelon; apple produced the fewest larvae. Although

larvae were produced on food hosts in the laboratory, field observations

30
indicate that tomato and muskmelons may not be preferred hosts for

increasing beetle populations.

Overwintering

 

Soil samples taken in the fall from strawberry plantings with
large spring populations failed to produce any significant numbers
of overwintering life stages. One sample, adjacent to the pear
orchard, contained 2 adults.

Cartons, which contained various life stages placed in the
soil on October 8, 1966 were examined on March 28 for insect survival.
None of the larvae survived; furthermore, no pupae were found in the
sand in cartons which originally contained larvae. Live adults were
found in 3 of the 5 cartons containing adults. Both newly—emerged
adults and field-collected adults survived. In each case, the
beetles were observed on the surface of the soil under the trash.
Further laboratory culture of 5 overwintering adults showed that they
were able to produce eggs. .

The data from the attractant traps are shown in Table 5. In
Investigation 1 initiated April 12, adults were trapped only in the
woodlots and only in the fermenting molasses traps. An explanation
for the low number of beetles collected can be deduced from the low
mean daily temperature of 50°F during the test period. Stelidota
geminata adults did not show migratory activity until the tempera—

ture reached 60—65°F. Large numbers of picnic beetles, Glischrochilus

 

sp. were collected in the bran molasses and grape juice mixtures in

all habitats.

31

 

on m noum>mfio

 

 

o o o o o o Meagan uowmm
ammo» +
o o m.o om we mm mommmaoa owawfiq
ma manum an:
N % coHummwumo>cH
um m noum>oao
o o o o o o Hoafium unwom
ammo» e
o o o I- NH oH maammaoa ensued
o o o In m.o I: mommmaoa a noun
mowom
o o o I: 0 II macaw a noun
0 o o I: o In some umwoz
m tnszNH Hfium<
H * oofiumwwumo>cH
.nouo comma .oouo Home oon uoHoooa uoHooo3 uoHnooa amwuoumz
coon .um coHcHEoo mayoanuum nozmwsm coon .um coficfiaon
cofiumooq

 

 

 

 

 

.eoma ..aoaz ..oo consume
.amuu ucmuomuuum you voodoAHoo moaned moonwaowimuooHHoUm mo Hogans owmuo>m oQHI|.n mqmmH

32

Since difficulty was encountered in separating the adults from
the bran baits the results are not summarized for Investigation 2.
As indicated in Table 5, under Investigation 2, 26-46 adults were
collected in the fermenting molasses traps placed in the woodlots.
Traps placed in the fruit plantings were essentially negative. Beetles
were not attracted to the paint primer card traps.

To verify the identification as S, geminata, 10 specimens were
forwarded to Dr. Melville H. Hatch of the university of Washington who

confirmed the identification.

Migration

Data obtained to determine date of first migration, peak of
migration, duration of migration, and distance of migration in rela-
tion to these factors are summarized in Table 6. The first adult
emergence, as recorded by trap captures, occurred during May 19-24.
Activity was highest in the overwintering woodlot sites. Migration
increased gradually, and reached a peak during JUne 14-19 (Fig. l).
The population remained at relatively high levels in the woodlots
throughout the remainder of the study period (Fig. 2). Beetles ex-
hibit little activity below 60°F but show increased response to
rising temperatures.

Adult captures in traps placed 80 ft from the overwintering
sites occurred approximately 6-10 days earlier than traps placed
600-800 ft away from the woodlots. This would indicate that adult

beetles do not fly great distances in one flight, but rather move in

33

.ooHuom mo Amov monsumuonEou mfiamo coma mo owmuo><

o

.mooum menu mo owned Hmwuwcfl onu cw noooaocw uOZo

.mHmawcm he handsomoud .oHon may cw oomonumon

o

.ommsu new: woman uozuo nuomwm;uo>ouom

 

 

one owe one owe can com com 000 0H0 omm nousumuomaou com:
a- moH an n- omH on ooH n- 0- 0- H 0oHeoos 00:0H3m
omH mm om om mNH HON oN ooH 0N HH H 0oHeoos cape .0m
oNH mNH mNH oHN ooH ONN OON mm Ha a H 00Heoos :oHaHaon
Hm N HH NN mN eNH ca 0- 0- 0- N 0oHeooe 00 .m 00 com
Nm mN w m NH mm mN m o 0- H enme0uo Hm0a :oHaHaoo
03803 «o .z 00 com
n- on mH m . oNH NN N o o o H enme0no e0m0a snow .0m
H- 00H no omN HaH H- an N o o N 0oHuoos No .3 0m om
mmH oe Ho HNH amH mm 0N H o o H 000:000 0H“:0 umansm
0N 0N on 00 «mm mN mm oH N H N 0oHeoos 00 .m 0H om
NNH me mN on 0aN NcH on m m o H 000:000 name :oHaHaon
NN mm on omH mHm mNH oHH oH o o N 0oHsoo3 «0 .z 00 cm
ma Ho oN mN com mHH Hm N o o H enme0no N000e0 snow .0m

N NHae om-oN 0N-NN NN-aH aH-eH aH-oH oH-o a0asn Hm-eN eN-mH ma000 aoH0m0oH

nomocsh meow meow meow meow meow meow ammo: an: mm: mo .02

 

nowuoa oonHoodm weapon nouoofiaoo wooasz

 

 

 

mood ..oo cowuuom

.maowu undouw .mommmHoS wcflucoauom OD muasom mumGHBuw-muoowaoum mo cowuouwwa o;H|I.c mqm<H

34

 

 

 

 

225 -
-—TRAPS BOFI
FROM EDGE
20% or woootor
--- TRAPS 600-
BOOFT. FROM
”5’ EDGE or
. WOODLOT
o.
E
k I50-
\
,0.
N
V l25-
8
V:
IL
Q IOO-
Q’
i
z ..
a 75 ,
§
50'-
25I’ \ l‘~
\\
o, J 1 1 1 l 1

 

 

A.
MONTH 5 5 8 _§_ 6 6 6 6 6 7

COLLECTION ' 19-24 24-3l 3l-O O-IO lO-I4 l4-I9 I9-22 22-26 26°30 30-7
PERIOD

Figure 1. Migration of Stelidota eminata adults to
fermenting molasses_ground traps. Berrien Co. Mich.,
1967.

350r

300 "

250-

200 -

IsoI-

35

 

 

IOO P

MEAN NO. OF ADULTS/TRAP

50-

 

0 1 1
new _5_ _ _6- a

COLLECTION I9-24 24-3l 3I-6 6-IO
PERIOD

1,
5

 

Figure 2. The mean number
molasses ground traps in 3

1 l 1 l l 41
L _6- .9. .2. _6- _7_
IO-I4 I449 19-22 22-26 26-30 30-7

of adults collected in fermenting
wood lots. Berrien Co. Mich., 1967.

36
a series of short flights. Wind direction influenced the numbers of
beetles collected in traps located outside the woodlots. Greater
numbers were trapped when the wind carried the odors of the fermenting

molasses into the woodlots.

DISCUSSION OF BIOLOGY

 

The biological investigations of S, geminata provide informa—
tion as to the reasons for the high infestations of beetles and
larvae which occurred in southwestern Michigan strawberry plantings
during June 1966.

Results of the overwintering study (Table 5) show that the
beetles do not overwinter in the fruit plantings as originally sus—
pected. Instead they hibernate in the woodlots and bordering thickets,
which.-are usually close to the strawberry plantings. Thus, within
a short period of time, under optimum temperature conditions, a large
number of adults can migrate into strawberry plantings and infest
fruit.

The adult beetle is the primary stage for overwintering. In
the overwintering study mortality was high in the containers placed
in the strawberry plot, but this was probably due to the severity of
conditions in the open field which would not exist under the woodlot
duff.

The initiation of migration and the extent of migratory
activity are related to temperature. Maximum daily temperatures of
85-95°F (70-75°F mean temperature) are optimum for migration. These
temperatures also accelerate ripening and the production of volatile
compounds--factors which attract beetles into the plantings. The
combination of overripe berries and optimum migratory temperature

37

38
appear to be the major factors in determining the extent of infesta—
tion.

Temperatures during the strawberry harvest in June 1966 were
above normal. In addition, pickers were unable to keep pace with the
rapid ripening of berries, resulting in overripe, fermenting berries
which accumulated in the plantings and lured the beetles from the
woodlots.

Experimental results demonstrate that migration is continuous
throughout the strawberry harvest. With the population remaining
within the woodlots, the possibility of migration and infestation is
continually present during harvest.

The time required for a complete laboratory generation was
19 days at 75°F. However, the rate of development in the field
would probably be accelerated due to higher air temperatures and
the effects of radiation on the temperature of the microclimate of
the beetles. Several generations are possible in one growing season
since no diapause was observed in the life history.

The above data, in conjunction with the fecundity findings
which demonstrated that 5 females could lay 150 eggs per week, further
elucidate the reason for the wide spread larval contamination in
strawberry fruit which caused cessation of harvest on June 22, 1966.

Stelidota geminata feeds on the majority of fruit crops grown

 

in Berrien County. However, feeding is restricted to fruit in direct
contact with the soil. The only host crops other than strawberries
that would appear to be endangered are muskmelons and tomatoes. As

stated previously beetles were found only on decaying melons and

39
decaying or split tomatoes. It is conceivable, however, that a
problem could develop in field-ripened processing tomatoes if

temperatures remained above normal.

CONTROL EXPERIMENTS AND RESULTS
MATERIALS AND METHODS

The field tests of this study were conducted in three locations
in Berrien County which were selected because of their central location
within the strawberry plantings of southwestern Michigan. The Dominion
farm is located 1 mile south of Napier Ave. on Morgan Rd. The St. John
farm adjoins the Dominion farm on the east boundary. The Swisher farm
is located on highway M—l40, 1 mile north of the junction of M—62 and
M9140.

The Dominion strawberry plot was 400x100 ft. It was subdivided
into 64 blocks, 25x25 ft in size. The infestation was observed to be
unevenly distributed within the experimental area. The paired block
experimental design was selected for all field tests and subsequent

statistical analyses.
CHEMICAL CONTROL
1966 Field Evaluations

The failure of the growers to control_§. geminata with conven-
tional air-blast sprayers and materials such as azinphosmethyl,
carbaryl and endosulfan during the 1966 strawberry season prompted
an investigation of the suitability of controlling the beetle with

~ high rates of spray/acre.

40

41

Based on preliminary bioassay studies, malathion and azinphos-
methyl were selected as candidate insecticides. Because the tests
were conducted after the normal strawberry harvest, berries grown in
northern Michigan were placed in the strawberry rows. Sprays were
applied with a Hudson knapsack sprayer at a rate of 400 gal dilute
spray/acre. High gallonages were used so as to completely cover the
foliage, fruit, and trash, and thereby test the efficacy of the insec-
ticides and not the application method. Malathion was used at a rate
of 4 lb active ingredient per acre; azinphosmethyl at the rate of 2 1b
active ingredient per acre. Treatments were replicated 3 times, each
replicate consisting of 1 row 13 ft long with 10 berries spaced 1 ft
apart in the row. Paired checks were used in adjacent rows. Evalua-
tions were made 1 and 2 days after treatment.

Malathion and azinphosmethyl (Table 7) were completely in-
effective 2 days after treatment even though application was made at
twice the recommended rate/acre. However, the materials were tested
under extremely high population pressures of 50-200 beetles per berry.

TABLE 7.--The effect of foliar applied toxicants for the control
of Stelidota geminata adults. Berrien Co., 1966

 

 

 

% damage at specified
days after treatmenta

 

Compound and

 

formulation Lb active/acre l 2
Malathion, 25% WP 4.0 33 96
Azinphosmethyl, 25% WP 2.0 17 96
Control 80 100

 

aTreated: July 31, 1966. Evaluated: July 31, August 1, 1966.

42

1966 Laboratory_Experiments

 

There is no published literature pertaining to the effective—
ness of pesticides for controlling_§. geminata; consequently, bioassay
techniques had to be developed to screen insecticides for subsequent
field testing.

Bioassays were conducted by dipping strawberries in insecticide
suspensions, allowing them to dry for 30 minutes and then placing l
berry in a 1 pint Plasti-Kan. Ten beetles were starved for 24 hr and
placed in each container. A container with l berry and 10 adults con-
stituted l replication; each compound was replicated 3 times. The
containers were placed on a table in a room which was maintained at
75°F and 50-70% relative humidity. Mortality was defined as the
inability of the beetle to maintain an upright position. Data were
recorded at 24 and 48 hr intervals.

The definitions of the proprietary chemicals used in this
study are as follows:

Azodrin--dimethyl phosphate, ester with_gis 3-hydroxy-N-

methylcrotonamide

Sumithion--0,0—dimethyl O-(4-nitro-mftolyl) phosphorothioate

GC-6506-—dimethy1 pf(methylthio) phenyl phosphate

03-13005--S-((2-methoxy-5-oxo—Ae-l,3,4-thiadiazolin-4-y1)

methyl) 0,0—dimethy1 phosphorodithioate

Imidan--0,0-dimethyl S—phthalimido-methyl phosphorodithioate

Lannate--methyl 0-(methylcarbamyl) thiolaceto-hydroxamate

43
Furadan--2,3—dihydro-2,2—dimethy1-7-benzofuranyl methylcarbamate
Gardona--2-chloro-l-(2,4,5-trichloropheny1) vinyl dimethyl

phosphate
Thiocron-—0,0-Dimethyl-S—(2-methoxyethyl-carbamoyl-methyl)-
phosphorodithioate
Zolone-—S-((6-chloro-2—oxo-3-benzoxazolinyl) methyl) 0,0—
diethyl phosphorodithioate
Mortality was observed in one set of control containers so
Abbott's formula (Abbott 1925) was employed in calculating mortality
in the corresponding treated containers. Mevinphos, parathion,
malathion and azinphosmethyl were highly effective against the adults.
The majority of the chlorinated hydrocarbon materials were ineffective.
Carbaryl, which was commonly employed as a spray chemical in the
strawberry plantings to control_§. geminata in June 1966 was non-toxic

(Table 8).

1966 Greenhouse Experiments

 

A suitable toxicant for commercial use must have an effective
residual life of from 3-5 days, must not leave a residue on the fruit
in excess of that established by law, and must have a clearance for
use on strawberries. Diazinon, azinphosmethyl, malathion, naled, and
mevinphos met the latter two requirements but nothing was known about
their residual effective life against the beetles.

Tb test these materials, strawberries were obtained from
strawberry plants grown in No. 10 cans. Strawberry clusters were

dipped in the insecticide suspensions and labeled. Greenhouse

44

TABLE 8.--Effect of various treatments applied for control of
Stelidota_geminata adults

 

 

 

% mortality at specified

 

 

Compound and Formulation/ time after treatment

formulationa 100 gal 24 hr 48 hr
Mevinphos, 5 1b/gal EC 0.8 pt 100 100
Malathion, 57% EC 1.0 pt 100 100
Azinphosmethyl, 2 lb SC 1.0 pt 100 100
Diazinon, 4 lb/gal EC 1.0 pt 100 100
Naled, 8 lb/gal EC 0.5 pt 100 100
Parathion, 8 lb/gal EC 0.2 pt 96 100
GC-6506, 4 1b/gal EC 0.5 pt 100 100
Lannate, 90% WP 4.5 oz 100 100
Sumithion, 4 lb/gal EC 11.0 fl oz 100 100
GS-13005, 3.67 lb/gal EC 1.0 pt 100 100
Azodrin, 5 lb/gal EC 5.0 fl oz 85 96
Furadan, 50% WP 1.0 lb 93 93
Imidan, 3 lb/gal EC 12.0 fl oz 60 85
Dieldrin, 1.5 lb/gal EC 1.0 pt 60 77
Perthane, 4 lb/gal EC 1.0 qt 0 9
Endosulfan, 2 lb/gal EC 1.0 qt 0 7
TDE, 50% WP 2.0 lb 0 o
Methoxychlor, 50% WP 3.0 lb 0 0
Oxydemetonmethyl, 2 lb/gal EC 1.0 pt 0 0
Carbaryl, 50% WP 2.0 lb 0 0
Thiocron, 2.5 lb/gal EC 12.0 fl oz 0 O
Zolone, 3 lb/gal EC 20.0 fl oz 0 0
Gardona, 2 lb/gal EC 2.0 qt 0 0
Chlorphenamidine, 50% EC 1.0 qt 0 0
Control A 10b 15b
Control B O O

 

aEC = emulsifiable concentrate; SC = spray concentrate; WP =
wettable powder.

bMortality in checks corrected by use of Abbott's formula
(Abbott 1925).

45
temperature was maintained at approximately 75:10°F. The berries were
picked at daily intervals and bioassays were conducted as described.
The results of this study are presented in Figure 3. Diazinon
and naled broke down after 2 days, malathion and mevinphos had
residual activity for 3 days, azinphosmethyl remained effective for

11 days and was still effective when the experiment was concluded.

1967 Field Experiments

 

Stelidota geminata infests fruit just prior to and during

 

harvest. Only those chemicals which can be applied close to harvest
would be adaptable to a control program. Mevinphos, which has a 1

day interval from application date to harvest, and malathion, which

has a 3 day interval, were chosen for work in the strawberry plot of
the Dominion farm. Applications were made with a Skibbe high pressure
sprayer equipped with a single row boom consisting of 3 nozzles. The
lateral nozzles were set at an inward angle, the middle nozzle directed
overhead so that the spray was directed into the row. Pressure was

set at 60 1b/in2 and the sprayer was calibrated to deliver 250 gal of
spray/acre. Malathion was applied at a rate of 2 1b active ingredient/
acre, and mevinphos at 1 lb active ingredient/acre. To determine
whether molasses enhanced the efficiency of malathion by attracting
beetles to the spray deposit, 2 gal of raw molasses/100 gal of water
were added to malathion as a separate treatment. Malathion, 4% dust,
was applied with a hand duster at the rate of 2 lb of active
ingredient/acre. Each treatment was replicated 4 times, a replicate

consisted of 6 strawberry rows 25 ft in length. _The baits, sprays

IIO
IOO
90
>30
:70
560
50
S40
2 3O
20

o\°IO-

 

O

l

'71]

a. AZIN PHOSMENTHYL

O

l

I

l 1 J

8 IO

1 l 1

2 4 6

DAYS AFTER APPLICATION
e NALED

IIO
I00

90-
80-

7O
60

50

3O
20

IO

°/o MORTALITY

40-

 

O

IOO

90
80
70
60
50
4O
3O
20
IO

0

MORTALITY

%

 

l J l J l

I 2 3 4 5
DAYS AFTE R APPLICATION

e. DIAZINON

T 7 T

l

I

1 l J J l

 

I 2 3 4 5
DAYS AFTER APPLICATION

Figure 3.
Stelidota
c, naIedT

If

l2

I

6

J
6

minata adults.
meVInphos; e, diazinon.

46

IIO
IOO
90
80
70
60

50
4O

3O
20

IO
O

‘7. MORTALITY

 

IIO
I00

90
80

60
5O
4O
3O
20

IO

0

MORTALITY

°/o

 

I l I l l [’1’ r'

70-

b. MALATHION

J l I

4 5 6

l l 1

I 2 3

DAYS AFTER APPLICATION
d. MEVINPHOS

 

1 1 l 1 1, TJ
I23456

DAYS AFTER APPLICATION

Residual toxicity of selected insecticides to

a, azinphosmethyl; b, malathion;

47
and dust were applied on June 13 and June 20, 1967. Control evalua—
tions were made on June 27 on the basis of percent damage to 25 of
the ripest berries in clusters which were in contact with the ground.
The middle 2 rows were evaluated in each block; the outer 2 rows were
employed as buffer rows.
The malathion and mevinphos treatments reduced injury by 8 and
3% respectively. Greater injury was recorded in the malathion plus
molasses spray and malathion dust treatments (Table 9). None of the
treatments gave commercial control of S. geminata.
INVESTIGATIONS INVOLVING
SYNTHETIC ATTRACTANTS
During the summer of 1966 a chance observation of a large re-

sponse of a picnic beetle, Glischrochilus fasciatus, to a paint touch

 

up job on a car in East Lansing, suggested the potential of a paint
attractant for S, geminata. The paint used was Duplicolor touch—up

(General MOtors Midnight blue, Stock No. DP—GM 44).

1966 Field Tests

 

Fourteen different paint products, including 12 Duplicolor
products and 2 Martin Senour products, were evaluated in July for
attractant properties. A trap was constructed by attaching a yellow
card 4-1/2X9-1/2 inches to a metal pole 3 ft above the ground and
fastening a lO-ml vial to the upper 3rd of the card. Both sides of
the card were then covered with Tanglefoot (to trap the insects

attracted to the boards). Two milliliters of paint were injected

48

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Howwwo HouooH mamm Ono mo nosofiaou uoc mouswwmm

 

 

 

asN- on an HH m Haw ooHN00m00Hoa Ham N +
m3 NmN .aoHe0mHmz
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0m on mm 0a mN.H om H0NNHH n .moeaaH>0z
0m we Nm pH m N3 NAN .aoHa00Hmz

aw Ne em aH oe 0H0H aoHe0mHma Nm
ImOmmmuoBIoooaoa o~am<

«a as 00 pH 00 0H0H HNH00smoeaaH00 NmN.H
Immm mMHOEIQOOCHOU

0mH as aN pH oe 0Hma HNe00amoeaaHNm NmN.H
ImOmmmaoaloomaom madam

mmN Hm wN pH os 0Hma aoHe00Hma Na
Imommmfioalnooauou

moocoummwwo N xomso odomouH ouom ucoaumoya
\coHumHDEHom

oesouw Ono ch5050u

muoumoHo mo mowuuoo owedwu
cu madame he owmsmn N coo:

 

 

mama ..oo cowuuom .Eumm coflcfiaoo

.mowuuoozmuum no somewaow

muoowfioum mo Houucoo osu cw mcoHumHDEuom mowowuommCH m30wum> mo mmoco>MDOOHMMII.m mqm<H

49
into the individual vials by means of disposable tuberculin syringes;
a separate syringe was used for each material to avoid contamination.
A wick was put in each vial to increase vaporization of the paint.
The traps were spaced approximately 20 ft apart. Each series of paints
was replicated 3 times—-once each in the following sites: Dominion
pear orchard, east side of Dominion strawberry patch and west side of
strawberry patch. When only small numbers of beetles were present,
trap captures were tabulated by removing S, geminata beetles from the
Tanglefoot. Sticky cards which contained large numbers of adults
were tabulated and the entire card replaced.

The response of_S. geminata to the series of paints is demon-
strated in Table 10. Beetles were attracted to all the traps but,
DP-GM 3 acrylic red primer was outstanding as an attractant (Plate VI).

Since the paint products were different in color, additional
investigations were initiated to determine the affect of color on re-
sponse. The same method as described previously was used with the
following exceptions: 12 different colored cards were used in place
of the canary yellow cards, the vials were covered with masking tape,
and only DP-GM 3 primer was used. No differences were found between
colors; however, the maximum response obtained was only 7 beetles.

Employing methods previously described in test 1, further work
was conducted between August 18 and September 1, 1966 to determine
the possible component or components in the DP—GM 3 primer responsible
for response. Samples of the individual components of the DP-GM 3

primer and related compound groups including alcohols, ketones and

 

 

auto p

Stock

DP- GI'I
DP- G}!
DP-lZ
DP-CC
DP—lI
DP-FI
3007
DP~1-
DP-l
DPS-
DP-(
628:
DPS
DP~

Bla

are

50

TABLE lO.—-Response of Stelidota geminata adults to touch-up

auto paints.

 

Dominion farm, Berrien Co., 1966

 

 

Mean number of beetles
captured during a 24 hr

 

Stock No.a Color of paint exposure period
DP—GM—3 Acrylic Primer (Red) 1883
DP-GME3 Acrylic Primer (Red) 1395
DP—l29 Colonial White 127
DP—CC-l46 Powder Blue 65
DP-l99 Auto White 52
DP-FM-48 Caspian Blue 48
3007 Clear Mix Acrylic 34
DP—l420 Antigua Red 32
DP-l66 Green (Sherwood) 3O
DPS-55 Gloss-Clear finish 9
DP—GM—44 Nfidnight Blue 8
6282 Clear Lacquer 7
DPS-15 Solvent (Clear) 5
DP—GM—2 Acrylic Solvent 4
Blank-Ck 5

 

 

aDupli-Color paints except material No. 6282 and 3007 which
are products of Martin Senour Paints, Inc., Chicago, Illinois.

51

 

 

 

Control DP-GM 3

Panel Acrylic paint primer

Plate VI.—-Response of Stelidota geminata adults to DP-GM 3
acrylic paint primer. Berrien Co. July 1966.

52
aldehydes were tested. During this period response to the primer was

very low and no response was observed to the other materials tested.

1966 Laboratory Experiments

 

To adequately test the response of beetles to the various com-
ponents of the DP-GM 3 primer an in-lab room was constructed in the
shape of a wind tunnel measuring 6X9X26 ft. Exhaust fans (12 inch)
were installed in each end to allow air flow in either direction.
Room temperature was maintained at 80:50F and the relative humidity
at 60-70% during the tests. A 5X7X24 ft cage was constructed of 32-
mesh Saran screen and suspended within the room to contain the test
insects.

The tests were conducted as follows: 1 m1 of paint primer was
placed in a lO-ml vial and attached to a yellow card covered with
Tanglefoot; the card was hung at one end of the room; one hundred
adult beetles were released at the opposite end; and the exhaust fan
was activated to draw the vapors eminating from the vial across the
point of beetle release. Several tests were conducted in this room
including beetles of different ages and beetles deprived of food for

varying periods of time. However, there was no response to the primer

in any of the tests conducted.
NATURAL ATTRACTANTS

1966 Field Studies

 

The response of S. geminata to fermenting fruits was reported

by several workers (Table l) and also was observed by the author under

53
field conditions. To verify these observations, experiments were
designed to determine response in the field to 2 natural attractants.

Ground traps containing fermenting grape juice and fermenting
molasses were placed in the Dominion cherry orchard and strawberry
field. Three traps of each test product were set out at 20 ft inter—
vals in each location on August 1, 1966. Data were collected the
following day.

Both fermenting grape juice and fermenting molasses attracted
large numbers of beetles in the 19 hr test period (Table 11). The
population in the strawberry planting was very large at this time due
to adult emergence from the soil; thus, the number of beetles collected
in the traps placed in the strawberry planting was greater than the
number collected in the cherry orchard where the population was a

result of migration to decaying cherries on the soil.

TABLE ll.--Response of Stelidota geminata to fermented grape
juice and molasses. Berrien Co., Mich. August 1966

 

 

Mean no. of adults collected in each
location during a 19 hr period

 

 

Material Strawberry field Cherry orchard
Fermenting 302 58

grape juice
Fermenting 390 38
molasses

Control 0 0

 

54

1967 Laboratory Studies

 

Preliminary field tests indicated a direct response to fer-
menting plant products. My next step in developing an attractant
bait mixture, which could be used as a field control, was a test of
suitable carriers. Two natural plant products, apple pomace and
wheat bran, were tested.

Five petri dish covers each containing a teaspoonful of dif-
ferent bait were randomly placed in a Saran screen covered cage
measuring 16X16X16 inches. Three cages were employed, each cage
representing a replicate. TWenty-five beetles starved for 24 hr were
placed in the center of each cage. The number of beetles present in
each of the baits was tabulated after 6 hr.

The response to the moist baits was significantly different
from the dry baits and the control (Table 12), indicating that the
moisture content of the bait in the field will be a factor in deter-
mining its effectiveness as a competetive lure with the ripe berries.

To determine whether beetle response to the baits could be in-
creased, several fruit essences and natural plant products were added
to the baits. The additives included: apple, grape, and cherry
essences; grape juice and fermenting grape juice. Spent grain, a
by-product of the brewing industry, was also tested as a possible
attractant.

The essences of grape, apple, and cherry did not increase re-
sponse to therait mixtures (Table 13). The response to grape juice

was significantly greater (Chi2 Test, 5% level) than moist bran as

55

TABLE 12.--Efficiency of various carriers in attracting
Stelidota geminata adults during a 6 hr exposure period

 

 

 

No. of beetles/replicate

 

 

Bait I 11a IIIa Totalb
Mbist apple pomace 8 15 10 33
Moist bran l3 3 9 25
Dry bran 2 l l 4
Dry apple pomace 0 l 0
Control 0 0 2

(moist filter paper)

 

aFive beetles in replicates II and III were not feeding on the
baits at the time of counting.

bResponse to the moist baits is significantly gEeater than the
dry baits and controls as determined by Chi2 Test (Chi 2;69.5, df = 2,
°¢= .01).

TABLE 13.--The response of Stelidota geminata adults to fruit
essences

 

 

Mean no. of beetles feeding on bait
Material after 3 hr exposure period

 

Investigation I
Cherry essence + pomace 3
Pomace + bran mixture 13
Investigation 11
Grape essence + pomace ' 9
Pomace + bran mixture 10
Investigation III

Apple essence + pomace 7
Pomace + bran mixture 11

 

56
shown in Table 14 (Investigation 1). There was no significant differ-
ence in response to moist bran and spent grain, a brewry by-product
(Investigation 2). The corncob-molasses mixture attracted a signifi-
cantly greater number of beetles than moist bran (Investigation 3).

TABLE l4.--Response of Stelidota geminata adults to natural
baits placed in cages

 

 

 

 

 

Replicatea
Type of bait I II III Totalb’C
Investigation 1
Bran-pomace mixture + 9 21 14 44a
fermenting grape juice
Bran-pomace mixture + 10 6 6 22a
grape juice
Investigation 2
Mbist bran 6 15 13 34a
Mbist spent grain 9 8 12 29a
Investigation 3
Corncob + molasses 14 15 20 49a
MOist bran 9 10 5 24b

 

aThirty adults/cage were released in Investigations 1 and 2,
25 adults/cage were released in Investigation 3. Counts were made
12, 3 and 10 hr after release in Investigations 1, 2 and 3 respectively.

bThe total numbers of beetles found not feeding on the baits
were 24, 25 and 2 for Investigations 1, 2 and 3 respectively.

CTotals followed by the same letter are not signifigantly dif-
ferent at the 5% level as determined by the Chi2 Test (Chi .2_9.86,
.87 and 44.2 for Investigations 1, 2 and 3 respectively.

57

BAITS

Laboratory Investigations

 

Control of adult beetles by growers with most of the commer-
cially available insecticides was not successful during the 1966 straw-
berry harvest season. Preliminary field tests demonstrated the in—
effectiveness and impracticability of spray chemical control methods.
Field, laboratory, and greenhouse experiments demonstrated that beetles
could be attracted to certain baits and response to these baits could
be improved by the addition of certain natural plant products. The
addition of an insecticide to the bait mixture, an old and accepted
control practice, could provide commercial control of S, geminata in
strawberry plantings.

To determine the effectiveness of insecticide-attractant baits
in protecting strawberries the following experimental method was
employed. A ripe strawberry was placed on wet sand in a petri dish
and the sand was sprinkled with the bait mixture at a rate equivalent
to 40 lb/acre. The dish was placed in a cage with 15 beetles that had
been starved for 72 hr. Ten different insecticide-attractant baits,
replicated 3 times, were tested in the laboratory for their efficiency
in killing S. geminata (Table 15). The number of holes in each berry
and the percent mortality were recorded after 24 hr.

Although the ratio of beetles to strawberry fruit was high the
majority of the bait mixtures produced a high degree of mortality and

protected the fruit from damage (Table 15). All of the mixtures that

58
contained grape juice or molasses as an attractant gave complete pro-
tection from injury, demonstrating their effectiveness as a competitive
lure with the ripe fruit.

TABLE 15.-—Efficiency of insecticide-attractant baits in
protecting strawberry fruit from Stelidota geminata

 

 

 

 

Type of Mean no. of Mean % mortality
bait holes/berry after 24 hr
Apple pomace—grape juice- 0 100
yeast-1.25% azinphosmethyl
Pomace—1.25% azinphosmethyl O 100
Corncob-molasses-l.25% azinphos- 0 100
methyl
Corncob-molasses-2.5% malathion 0 98
Attapulgus clay-molasses- O 95

2.5% malathion

Apple pomace-5% Furadan 0.3 98
Wheat bran-5% malathion 0.3 95
Apple pomace-5% Dylox 1.3 91
Bran-apple pomace- 2 80
1.25% azinphosmethyl
Bran-citrus pomace-5% Dylox 1.3 76
Controla 1/3-1/2 berry O
consumed

 

aInitially several feeding holes were made but after 24 hr they
coalesced into 1 or 2 large cavities.

59

1967 Field Evaluations

 

The corncob-molasses-insecticide (malathion or azinphosmethyl)
combination was selected for preliminary field tests because of its
commercial availability and relatively low cost. Tests were conducted
at the Dominion strawberry plot in May. At this early date, straw-
berries were not present in the field so ripe fruit had to be provided.
Each treatment consisted of a l X 1 ft area in the strawberry row.
Laboratory studies had shown that the presence of moisture affected
response to the baits; therefore, two thirds of the treated plots were
pre-moistened. Three berries were placed in each section and the bait
was distributed at a rate equivalent to 40 lb/acre. Fifteen beetles
were put in each area and a wood frame covered with 32-mesh Saran
screen was placed over them. Each treatment was replicated 3 times.

As shown in Table 16 the strawberry fruit in the plots that were
pre—moistened and treated with the corncob—molasses baits, had signifi-
cantly less injury than the controls as determined by Duncan's multiple
range test at the 5% level (Duncan 1957).

Further testing of the effectiveness of baits as a control

measure for Stelidota geminata was conducted during the harvest season

 

in the strawberry plots in Berrien County. Four formulations of

baits were applied as shown in Table 9. The replicates, dates of
application and evaluation method were the same as described previously
in the "Chemical Control-1967 Field Experiments" section. The fine
granule corncob-molasses—5% malathion bait gave the best protection.

The maximum reduction in injury was 23%, the minimum was 8% (Table 9).

60

TABLE l6.--Reduction of Stelidota geminata adult feeding on
strawberry fruit in plots treated with corncob-molasses baits.
Dominion farm, Berrien Co., Mich., May 1967

 

 

 

Mean no. feeding
Treatment holes/berrya

 

On moist ground
Corncob-molasses-l.25% azinphosmethyl .66a
Corncob—molasses—5.0% malathion 1.00a

On dry ground
Corncob-molasses-l.25% azinphosmethyl 2.33ab

Control 5.5b

 

aMeans followed by the same letter are not significantly dif-
ferent, as determined by Duncan's multiple range test for correlated
and heteroscedastic means at the 5% level.

To further determine the effectiveness of the corncob-molasses—
5% malathion bait another series of treatments was evaluated in the
blocks previously treated with this bait. Infested berries were re—
moved from an 8 ft section in 4 treated and adjoining check rows.
The bait was immediately spread over the rows by hand at a rate
equivalent to 40 lb/acre. Each treatment was replicated 4 times.
Treatments were made on June 28 and July 1, 1967. On July 4, 1967
all ripe berries in the rows were harvested and classified. Evalua-
tion showed injury in 4.3% of the berries in the treated plots and
in 20.6% of the check berries.

Work was initiated in June 1967 to compare the relative
attractiveness of liquid and dry baits. The following baits were

included: liquid molasses—1% azinphosmethyl, liquid molasses-yeast-l%

61

azinphosmethyl, corncob-molasses-l.25% azinphosmethyl, and apple
pomace-1.25% azinphosmethyl plus DP—GM 3 primer. The liquid molasses
traps were the same type as described previously. The granular baits
were placed in piles on Saran screen on the ground. The purpose of
the primer-pomace combination was to study response to the paint
rather than the pomace, which was employed as a medium to trap the
adults. A lO-ml vial with 5 m1 of primer was placed on the pomace
pile. The traps were distributed in 4 woodlots and left for 4 days.

Table 17 shows the outstanding attractant properties of the
fermenting molasses—azinphosmethyl liquid baits in contrast to the
other baits tested. Molasses-corncob-azinphosmethyl baits placed in
piles possessed the least attractant qualities.

To demonstrate the usefulness of fermenting molasses traps as
a control measure, a typical commercial setting at the St. JOhn farm
was selected. The field is bordered by a woodlot on the south, a
cherry orchard on the east, apple orchard on the west and melon field
on the north. Ground traps, consisting of 50% raw molasses, yeast
and 1% azinphosmethyl in 7 oz paper cups, were distributed around the
perimeter of the field at intervals of 20 ft. The cups were set on
the ground at a 45° angle and pointed away from the irrigation sprinklers.
The traps in the woodlot were located 5 ft in from the edge, the
orchard traps were placed under each tree in the lst row and traps at
the north end of the field were put in the strawberry row 2 ft from
the end. The traps were set out on June 12, and evaluated June 16,
1967. Two aerial applications of corncob-molasses-l.25% azinphosmethyl

bait were applied over the entire field.

62

 

Hoawum magma
0HHNA0m m zu-Na «0 HmH>

 

 

 

 

 

mm mm o o H + Hanuoamonmcfinm Naloomaoa madam
OHNQ Damn
NH NH o m N HNa0mamoeacH~0 NmN.H
InoocMOOImommm~oz
ahnuoamonacflnm NH
mas NHH an NsN meN -0mm0N-m0mmaHoa aHaaHH
Hmnooamocmcwum NH
on an 0 ma o Imommmaoa owsqu
Hmuoe Honmfizm Amvcsom .om szcsom .um :oNcHBon ufimm
coNumooH uoHooo3
comm cw amuu\moHuooo mason mo Hooaoz
Noma mesh ..noaz ..oo cowuuom .muoH
no003 cw noomam mcowomHSEuow Damn hum new owovwa 0o mumcHEmw.muooN~oDm mo uncommomll.mfi mqm<H

63

The greatest number of beetles was trapped in the woodlot

(Table 18). Approximately 4500 beetles were trapped in 4 days in

the woodlot. Traps placed in this habitat the following week averaged

30 beetles in 4 days. After 2 weeks approximately 150 beetles were
collected per trap. The data in Table 18 show that the smallest
number of beetles was collected farthest from the woodlot.

tions of berries in the field showed the infestation to be minimal.

Observa-

Ripe and overripe berries were observed uninjured within 12 ft of the

edge of the woodlot.

TABLE l8.--Response of Stelidota geminata adults to fermenting

 

molasses ground traps placed around a 2.5 acre strawberry field.

St. JOhn farm, Berrien Co., Mich., June 1967

 

 

Mean no. of beetles collected per trap
during a 4 day period at specified
distance (ft) north of the woodlot

 

 

Site 0 20 100 200 350 450
Edge of woodlot 540 --- --- --- --- ---
Cherry orchard —-- 445 400 125 35 17
Apple orchard —-- 19 18 ll 6 14
North end of field --— -—- --- —-— —-- 3O

 

a
Not tested.

The main disadvantage to the above means of control is the in-

herent high mammalian toxicity of azinphosmethyl.

The oral LD of

this material to rats is about 18 mg/K.of body weight.

bait stations contain a lethal dose for a human.

material is limited because less toxic materials to humans such as

The choice of a

Thus, these

64
carbaryl and methoxychlor are non—toxic to S, geminata. However,

malathion is highly toxic to S, geminata and has an oral LD to rats

50
of 1,400—5,8OO mg/K.making it one of the safest of all insecticides
to humans.

To determine the residual activity of malathion, tests were
cOnducted with 2 formulations; malathion (25% WP) and Malathion LV
Concentrate. The mixtures prepared were (1) 50% molasses solution
plus enough malathion WP to make 2.5% active ingredient, (2) 5 fl oz
of 50% molasses solution plus one half milliliter of Malathion LV
Concentrate. Bioassays were carried out daily by placing 10 adults in
a 1 pint Plasti-Kan container along with a sample of the bait. Each
mixture was replicated 3 times.

Within 2 days the malathion WP—molasses mixture was non-toxic
to adult beetles. The mixture that contained Malathion LV Concentrate
resulted in 100% mortality throughout the test period which was ter-
minated after 1 week.

To determine what effect the odor of Malathion LV Concentrate
had on the response of beetles to fermenting molasses a comparison
between liquid molasses ground traps containing azinphosmethyl (25%
WP) or Malathion LV Concentrate was carried out with methods described
previously. The toxicant employed was found to have no effect on the
response of the beetles to the molasses.

Ground traps, to be economically practical, must have a field
longevity of several days. The longevity of fresh and 5-day old fer-
mented molasses solutions containing 1% azinphosmethyl was tested in

ground traps in 3 locations within the Dominion woodlot.

65
Both mixtures retained their attractant properties during the
test period. However, as shown in Table 19, the response to the fresh
mixtures is significantly different from the 5-day old mixtures as
determined by the F test (5% level).

TABLE l9.--Response of Stelidota geminata to 5—day old and
fresh molasses + yeast ground traps. Berrien Co., Mich., 1967

 

 

 

 

 

Mean no. of beetles/trapa “Ti
Age of fermenting mixture at 3_
beginning of exposure period July 2-4 July 4-7
0 days 27a 82a
.4
5 days 4b 39b J

 

 

aMeans flanked by the same letter are not significantly dif—
ferent at the 5% level (F test).

 

 

CONTROL DISCUSSION

 

In field studies in 1966 and 1967 indicated that chemicals
sprayed on the strawberry foliage did not provide satisfactory con-

trol of Stelidota_geminata. This was probably caused by the dense

 

plant foliage, which limited the penetration of sprays and the adult
feeding on the underside of the fruit, which made the chance of contact
with insecticide remote.

The outstanding response to DP—GM 3 auto paint primer in 1966
could not be duplicated in 1967 even though many experiments were con—
ducted in the laboratory and field. One obvious difference between
the populations was that the beetles responding in July 1966 were
emerging from the strawberry plantings that were devoid of berries
whereas the population studied in 1967 was in the woodlot--a habitat
where decaying vegetation and moisture were available.

The injury to the fruit in the strawberry plots treated with
spray chemicals and baits appear to be excessive (Table 9); however,
the injury represents only that present in overripe berries touching
the soil. Thus, the total percentage of injury in all ripe berries
would be less than that shown in Table 9.

Several factors influenced the results of the plots at the
Dominion farm. A major factor was that each set of treatments was
followed by heavy rainfall. Rainfall of this nature rapidly decreases
_the effectiveness of the baits because it washes the molasses from

66

67
the carrier. In addition, washing and hydrolysis decrease the activity
of the chemical materials. Secondly, the plots were under heavy popu-
lation pressure from adjoining checks. However, to correct this situa-
tion would have necessitated treatment of the entire planting. Thirdly,
the experimental area was not representative of commercial plantings
because it was not mulched, irrigated or harvested. Mulch in the com-
mercial fields was observed to contribute significantly to the effec-
tiveness of the baits because it kept the bait moist and provided
shelter under which the beetles could feed. Harvesting presumably
would increase the chance of contact with bait since removal of the
injured berries would cause the beetle to move in search of food. The
above factors probably reduced the effectiveness of the baits more
than the effectiveness of chemical treatments and probably accounted
for the lack of significant difference between treatments.

Growers who treated their plantings with the corncob-molasses
bait were able to completely harvest the crop in 1967, even though
infestation occurred before control applications were made. The use
of fermenting bait stations to intercept the migration of S, geminata
proved to be a satisfactory means of control. This method has the
advantages of high drawing power, economy, safety, no residue problem,
ease of distribution and little interference with non-target species.

The only materials and equipment required for preparation of the
bait stations are raw molasses, yeast, water, Malathion LV'Concentrate
and an eye dropper. Distribution of the bait stations requires no

elaborate or expensive equipment and little time. One man had no

68
trouble preparing and distributing bait stations for a 2.5 acre field
in 2 hr.

The bait station is the most economical of the control methods
tested. A comparison of costs between bait stations and bait broad—
casting of a 2.5 acre field disclosed that l aerial treatment costs
$l4/acre or $35 for the field. If 3 applications are made, the total
cost for protection is $105. Paper cup bait stations spaced 20 ft
apart would cost approximately $3/application or $12-15 total for 4-5
baitings during the season. A difference of $90-93 for the season.

The findings that Malathion LV Concentrate had residual activity
of at least 1 week was probably due to immiscibility which did not
allow hydrolysis of the malathion. The use of malathion as a toxicant
negates the hazard aspect.

Liquid bait stations have no affect on non-target species. The
only other specimens commonly collected were picnic beetles,

Glischrochilus sp., therefore, this technique would be adaptable to a

 

future integrated control program.

SUMMARY

A new pest of strawberries--the strawberry sap beetle,

Stelidota geminata——caused an estimated 2—3 million dollar loss to

 

the Michigan economy in June 1966. Damage was caused by the feeding
of adults and larvae.

Mass rearing in the laboratory for biology and control studies
was carried out by culturing beetles in 2-quart, wide-mouth jars.
Mbist peaches were provided as a food source.

Life cycle studies showed that there are 3 larval instars and
completion of development from egg to adult requires an average of
19 days at 75°F. Adult lifespan averaged 127 days; the oviposition
period averaged 101 days; and the average number of eggs per day was
4.3 with a maximum of 16.

Adult beetles fed primarily on the underside of ripe and over-
ripe fruit in contact with the ground. One to several feeding gal-
leries were made in the strawberry fruit depending on the number of
beetles present. The individual galleries coalesced into large
cavities after several hours of feeding. Larvae also fed in the in—

terior of the fruit. Host crops of Stelidota geminata in Berrien Co.

 

were sour and sweet cherry, dewberry, tomato, muskmelon, peach, pear
and apple.

Fermenting molasses ground traps were employed to determine
the side of overwintering and time of migration. Adults overwinter

69

70
in the woodlots and thickets around the fruit plantings. When the
mean temperature was above 65°F migration from the woodlots occurred.
The odor of ripe, overripe or decaying strawberries attracted adults
to the strawberry plantings. The peak of migration coincided with the
peak of the strawberry harvest.

Application of spray chemicals on the strawberry foliage and
fruit at rates up to twice the recommended gallonage per acre did
not produce control. Bioassays of 24 chemical compounds showed that
the following were toxic to S, geminata adults: mevinphos, malathion,
azinphosmethyl, diazinon, naled, parathion, GC-6506, Lannate, Sumithion,
GS—l3005, Azodrin, Furadan, Imidan, and dieldrin. The other compounds
tested were ineffective.

Outstanding response to a synthetic attractant, Duplicolor
auto primer touch-up paint DP—GM 3 was demonstrated in July 1966.
However, subsequent work in 1966 and 1967 in the laboratory and field
failed to demonstrate exceptional attractant properties of this
material.

Adult beetles showed significant response to the following
natural attractants: bran, apple pomace, fermenting molasses, and
fermenting grape juice. Fermenting grape juice and fermenting
molasses were highly attractive. Two methods of control were
developed that employed molasses as an attractant. The first method
utilized a bait consisting of corncob-molasses—l.25% azinphosmethyl
that was broadcast over the strawberry fields at a rate of 40 lb/acre.
This bait was applied over a majority of the commercial strawberry

acreage in southwestern Michigan in June 1967 and produced satisfactory

71
control. The second method of control was the placement of liquid
fermenting molasses-yeast-insecticide poison bait stations around the

perimeter of the strawberry field to intercept the migration of adults.

LITERATURE CITED

 

Abbott, W. S. 1925. A method of computing the effectiveness of an
insecticide. J. Econ. Entomol. 18: 265-7.

Blatchley, W. S. 1910. Coleoptera of Indiana. Nature Publishing
Co., Indianapolis, Ind. P. 641.

Boving, A. G. and J; G. Rozen. 1962. Anatomical and systematic
study of the mature larvae of the Nitidulidae (Coleoptera).
(Reprint) Entomologiske Meddelelser 31: 265-99.

Connell, W. A. 1956. Nitidulidae of Delaware. Delaware Univ. Agr.
Exp. Sta. Bul. 318.

Dorsey, C. K., and J. G. Leach. 1956. The Bionomics of certain
insects associated with oak wilt with particular reference to
the Nitidulidae. J. Econ. Entomol. 49: 219-29.

Duncan, D. B. 1957. Multiple range tests for correlated and
heteroscedastic means. Biometrics 13(2): 164-76.

Lindgren and Vincent. 1953. Nitidulid beetles infesting California
dates. Hilgardia 22(2): 97-118.

Parsons, C. T. 1943. Rev. of Nearctic Nitidulidae. Bull. Mus.
Comp. Zool. Harvard XCII: 209-10.

Schmidt, Carl T. 1935. Biological studies on the nitidulid beetles
found in pineapple fields. Ann. Ent. Soc. Amer. 28(4):
475-511.

Siegel, S. 1956. Nonparametric Statistics for the Behavioral
Sciences. MCGraw-Hill, N.Y. Pp. 42-47.

Snedecor, G. W. 1956. Statistical Methods. 5th Ed., Iowa State
College Press, Ames, Iowa. Pp. 251-53.

VOgt, G. B. 1950. Occurrence and records of nitidulids. Coleop.
Bul. IV(6): 81-91.

. 1951. Occurrence and records of nitidulids. Coleop.’
Bul. V(1): 4-11.

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