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lNSECT PREDATORS OF THE SACK PINE
PARASITE MELAMPYRUM UNEARE DESR.

Thesis for the Degree of M. S.
MECHIGAN STATE UNIVERSHY
GARY V‘ MANLEY
1968

«gnawuzzlyujuwumu :11an [3 $116]

Umversity

 

 

ABSTRACT

INSECT PREDATORS OF THE JACK PINE
PARASITE MELAMPYRUM LINEARE DESR.

 

By Gary V. Manley

Based on evidence collected during the summer of 1965 and 1966
insects play an important role in the distribution and abundance of

Melampyrum lineare, a vascular plant parasite of Jack pine. While

 

many species of insects feed actively on Melampyrum, grasshoppers

 

appear to play a major role as insect herbivores.

The major part of vegetative feeding on the plant takes place
before mid-summer. During the latter half of the summer direct pre-
dation upon seeds and seed producing organs of the plant are of
major importance.

Seed predation represents the major direct influence of in-

sects upon Melampyrum although flower and foliage feeding was also

 

documented.

Arthropod predation upon Melampyrum was inflicted by about 53

 

arthropods during this study, mostly insects.

The investigations were conducted using insecticide treated
and untreated control plots in which comparisons were made on all
types of damage involving insect predation and seed production in the
field. Within the plots yearly population sizes and survivorship of

the plants in treated and untreated plots were recorded.

Gary V. Manley
Laboratory rearing studies were conducted for the purpose of
obtaining adult stages for identification while life cycle studies
were conducted both in the field and in the laboratory.

Because Atlanticus testaceus (Scudder) appears to be the major

 

direct insect influence on Melampyrum populations much emphasis is

 

directed at this relationship.

While Atlanticus is perhaps the only insect species that inflects

 

significant damage to wide ranging Melampyrum populations, other insect-

 

Melampyrum relationship can not be completely overlooked. Activities of

 

insects other than Atlanticus are viewed in this study as a combined in-

 

fluence effecting local population. In isolated situations the effect
of various insect species can be pronounced.
Two insects which are not well understood in relation to

Melampyrum are the carabids and the formicids. The combined relation—

 

ship of these plus Atlanticus or their influence as separate entities

 

may be of importance when better understood.

In the spring Atlanticus feeds on vegetative portions of the

 

plant. This continues until seed production, at which time the grass-

hopper gradually switches to eating Melampyrum seeds. It would appear

 

that in the forest situation where this study took place Atlanticus is

 

host specific on Melampyrum.

 

.5. testaceus may serve as a regulatory factor on_§. lineare
populations in the natural systems where this study was conducted.

Population densities of Melampyrum are dependent to various degrees on

 

the amount of predation.

Gary V. Manley
Melampyrum populations respond to the predatory activities of
Atlanticus by producing fewer capsules and in long term population
fluctuations. In areas treated to control insects, populations of
Melampyrum tend to increase relative to untreated areas. The greater
the amount of predation between treated and untreated plots, the greater

is the difference in the number of capsules produced per plant.

INSECT PREDATORS OF THE JACK PINE

PARASITE MELAMPYRUM LINEARE DESR.

 

By

IV]

Gary V3HManley

A THESIS

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

MASTER OF SCIENCE
Department of Entomology

1968

5 ./ 4;- c") '7’

ACKNOWLEDGEMENTS

The author wishes to express his appreciation to Dr. Gordon E.
Guyer, Chairman, Department of Entomology, for providing financial
assistance and serving on the author's guidance committee during this
study.

Particular thanks are expressed to Dr. James Butcher, who
served as the author's major advisor and was constant source of
encouragement, enthusiasm, and guidance in the completion on this
study.

Particular thanks are also extended to Dr. John Cantlon (Dept.
of Botany) for his constant encouragement and direction in this
project.

I wish also to thank Dr. Gerhardt Schneider (Dept. of Forestry)
who served on the guidance committee.

Acknowledgements and thanks are also extended to those who
either made or helped with identifications of the insects. Dr.
Cantrall, University of Michigan who identified the Orthroptera,

Dr. Edward O. Wilson, Harvard University, who identified the Formicidae.
Thomas Hlavac for his help with the Coleoptera, T. Shaw for the
Hemiptera, John Newman and J. P. Donahue for their help with Lepidoptera
and Jim Shaddy for the Diptera.

Finally a note of deep appreciation is extended to my folks,
Mr. and Mrs. Wesley Manley and to my wife Elinar for the most impor-
tant part they played in my completion of this study.

ii

TABLE OF CONTENTS

Page

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 1

L0

METHODS AND PROCEDURES . . . . . . . . . . . . . . . . . . . . .

Site Location and Description .
Plant Studies .

Insect- -Me1ampyrum Relationships
Insect Rearing Methods

 

\oxl-L‘w

THE ARTHROPOD FAUNA OF MELAMPYRUM . . . . . . . . . . . . . . . 11

 

ORTHOPTERA . . . . . . . . . . . . . . . . . . . . . . . 12
COLEOPTERA . . . . . . . . . . . . . . . . . . . . . . . 21
LEPIDOPTERA . . . . . . . . . . . . . . . . . . . . . . . 34
HEMIPTERA . . . . . . . . . . . . . . . . . . . . . . . . 41
NEUROPTERA . . . . . . . . . . . . . . . . . . . . . . . 42
THYSANOPTERA . . . . . . . . . . . . . . . . . . . . . . 42
HOMOPTERA . . . . . . . . . . . . . . . . . . . . . . . . 42
HYMENOPTERA . . . . . . . . . . . . . . . . . . . . . . . 43
ARANEIDA . . . . . . . . . . . . . . . . . . . . . . . . 44

VERTEBRATES . . . . . . . . . . . . . . . . . . . . . . . . . . 44
RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . 45
Experimental Studies with Field Populations

of Melampyrum . . . . . . . . . . . . . . . 45
Arthropod Influence on Melampyrum . . . . . . . . . . . . 54

 

 

CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . 75

iii

Figure

LIST OF FIGURES

Layout for the treated and untreated plots used
for the study of Melampyrum during 1965 and
1.966 O O O O O O O O I O O O O O O O O O O O

 

Feeding preference study of grasshoppers found
in the ”HGQ" area . . . . . . . . . . . .

Insect feeding on Melampyrum branches for 100
randomly located plants in treated and
untreated plots . . . . . . . . . .

 

Carabid beetles collected in pit traps in all
plots in 1965 . . . . . . . . . . . . . . . .

Replicated survivorship curves showing number
of Melampyrum plants on July 25, 1965 and
numbers surviving until harvest at two-weekly
intervals after seed production began
(August 3, 1965) for a five meter square area
in the ”HGQ” plot . . . . . . . . . . . . .

 

Replicated survivorship curves showing number
of Melampyrum plants on May 11, 1966 and
numbers surviving until harvest at two-weekly
intervals after seed production began
(August 2, 1966) for a five meter square area
in the "HGQ" plot . . . . . . . . . . . . . .

 

Replicated survivorship curves showing number
of Melampyrum plants on July 25, 1965 and
numbers surviving until harvest at two-weekly
intervals after seed production began
(August 3, 1965) for a five meter square area
in the "127" plot . . . . . . . . . . .

 

Replicated survivorship curves showing number
of Melampyrum plants on May 11, 1966 and
number surviving until harvest at two-weekly
intervals after seed production began
(August 2, 1966) for a five meter square area
in the "127” . . .

 

iv

Page

16

20

33

47

48

49

50

Figure Page

9. Replicated survivorship curves showing number
of Melampyrum plants on July 25, 1965 and
numbers surviving until harvest at two-weekly
intervals after seed production began
(August 3, 1965) for a five meter square area
in the ”131” plot . . . . . . . . . . . . . . . . . . . 51

 

10. Replicated survivorship curves showing number
of Melampyrum plants on May 11, 1966 and
numbers surviving until harvest at two-weekly
intervals after seed production began
(August 2, 1966) for a five meter square area
in the ”131” plot . . . . . . . . . . . . . . . . . . . 52

 

11. Replicated spring counts (May, 1967) of
Melampyrum seedlingsfor a five meter square
area in all plots . . . . . . . . . . . . . . . . . . . 53

 

12. Treated and untreated plots in relation to the
number of capsules per plant for the 100
randomly located plants around the ten by ten
meter perimeter . . . . . . . . . . . . . . . . . . . . 57

13. Difference in number of missing branches between
treated and untreated plots for 100 randomly
located plants on the ten by ten meter perimeter.
Differences equal damage in the treated plot
minus untreated plot . . . . . . . . . . . . . . . . . 58

14. Seeds per plant based on the number of seeds
naturally released on air drying from plants
harvested in twenty 0.5 by 0.5 meter quadrants
at four week intervals from first seed matura-
tion from the ”HGQ" plot . . . . . . . . . . . . . . . 66

15. Capsules per plant from plants harvested in
twenty 0.5 by 0.5 meter quadrents at four
two week intervals from first capsule

formation, ”HGQ” 1965 . . . . . . . . . . . . . . . . . 66
16. Number of flowers per plant for 100 plants

in the “HGQ” plot for August 13, 1965 . . . . . . . . . 66
17. Percent of plants alive for five square meters

in the "HGQ" plot, 1965 . . . . . . . . . . . . . . . . 66

18. Observed position of Atlanticus on Melampyrum
plants during night observations . . . . . . . . . . . 67

 

 

V

Figure

19. Total number of leaves with each degree of
damage for 100 plants in the "HGQ" plot
for August 13, 1965 . . . . . . .

20. Number of leaves per plant in treated and
untreated plots for 100 plants in the ”HGQ”
plot, 1965

21. Number of flowers per plant in treated and

untreated plots for 100 plants in the ”HGQ"
plot, 1965

vi

Page

67

68

68

LIST OF APPENDICES

 

Appendix Page
I. Insects of Melampyrum lineare . . . . . . . . . . . . . . 77
II. Feeding habits of Melampyrum insects . . . . . . . . . . 81

 

vii

INTRODUCTION

Melampyrum lineare Desr. (Scrophulariaceae), also known as

 

cow-wheat, is a green vascular plant which grows parasitically on the
roots of various other vascular plants. It appears to be involved in
a large number of interspecific interactions in the ecosystems of cer-
tain northern Michigan forest types. The mature plant varies greatly
in size, ranging from 5 to 40 cm. tall. Within the vegetation types

in which it occurs the distribution of Melampyrum lineare is very

 

spotty, and there is no obvious reason why it is present in one area
and not in an adjacent spot.

In the jack pine, oak and aspen stands where it occurs,_M.
lineare is commonly the major annual herb on the forest floor. In
some sites the plant is the only abundant herb outside of Carex

pensylvanica. It is interesting that while the plant frequently

 

parasitizes the roots of pine it is uncommon in dense, pure stands of
pine. The few plants that are found in this situation are scattered
and small. Mixed stands of hardwoods and pines with good shrub layers
of blueberry and other species and a good cover of mosses and lichens
appear to support the largest populations of_M. lineare in northern
Michigan.

Earlier studies (Cantlon, Curtis & Malcolm 1963, Cantlon &
Curtis unpublished) seemed to indicate that herbivores produced
enough plant damage to influence the population size of_M. lineare.

l

2

The present study is an attempt to characterize the insects associated
with this plant species, and to estimate the relative significance of
those insects which graze upon it or which eat its seeds.

Numerous workers (as an example Huffaker, 1959; C. B. Huffaker
& Kennett, 1959) have shown that plant populations can be influenced
by the insects in the same community. If_M. lineare populations are
significantly influenced by insect grazing and predation, drastic
reduction of the insect populations with pesticides should produce a

measurable change in the Melampyrum populations. This experimental

 

"'

reduction of the pesticide sensitive invertebrate populations together
with the study of the normal insect faunas on untreated controls is

the basic approach applied to this study.

METHODS AND PROCEDURES

The approaches used in studying insect predation on Melampyrum

 

lineare are considered in three parts, (a) site location and descrip-
tion, (b) methods relating to the plant populations, and (c) those re—
lating to the insectjM. lineare relationships. Three study areas were
located in the northern portion of Michigan's lower peninsula. In
each site two plots were established. One was treated with insecti-
cides to reduce the insect population, the other was left untreated

for comparison.

Site Location and Description

The site where most of the insect study took place is in Fife
Lake State Forest, SW 1/4 of SE l/4 of Sec. 23-T25N—R9", in Grand
Traverse County and is designated ”HGQ.” The study areas at this site
are located on well drained upland ground several hundred meters south-
east of Headquarters Lake. The untreated plot is the closest to the
lake with the treated plot about 100 meters further from the lake.
The second study area, designated ”131” is located at T25N—R9W—Sec. 27
of Grand Traverse County just east of highway U.S. 131. Both the "HGQ”
and ”131" sites are a short distance south of Fife Lake and about 15
miles north of Cadillac, Michigan. The third site is in Roscommon
County 5 miles south of Houghton Lake at Sec. 27 T21N—R4W. It is

3

4

about 1 mile west of highway M+127 adjacent to a gravel road leading to
an oil field and is designated "127".

All of the sites were fairly free from human disturbances.
In 1965, the "127" site was disturbed by blueberry pickers several
times, resulting in a few stakes being pulled. The same thing happened
once in 1966, but damage to the research in progress was slight. The
"131" site was located on private land and appeared undisturbed
throughout the study. Riding horses occasionally ran through the "HGQ"
site, but damage was minor.

All sites were open second growth jack pine—oak forest with

understories of low bush blueberry and other shrubs, Pensylvanica

 

and other herbs, and various bryophytes and lichens. The soil in all
cases was dry and sandy, probably Grayling or Croswell sand soil

series.
Plant Studies

The treated and untreated plots were 22.86 square meters and
each was further divided into subsections (Fig. 1). In the center of
the 22.86 M? plot was a smaller unit measuring 10 M2. The perimeter
of this unit was used for one set of observations, and centered within
this perimeter was a 7.62 M2 plot. This smaller plot was marked off
in a series of transects for spring and fall counts. Between the
outer perimeter of the 22.86 M? and the perimeter of the 10 M2 plot
were located two 5 x 10 meter plots. These 5 x 10 meter plots were
located in this belt wherever the M. lineare populations were reason-

ably uniform. Ten 1 square meter quadrats were located at random

Fig.l-- Layout for the treated and untreated plots
used for the study of Melampyrum during 1965 and 1966.

 

22.86 meters square or 75 feet square

 

5 meters

_LJ

 

El:
10 meters 3 D

7.62 meters
or 25 feet :]

 

 

 

 

 

 

 

 

 

 

 

10 meters

U U
[j [:P 87—7-1 meter plots
m r

 

 

 

 

 

 

 

 

Enlargment of the one meter square

 

H
UP

> O- 5 meter plots

 

 

 

 

. 1-4 = harvest progression of Melampyrum plants
from 0.5 meter square plots at two week
intervals during seed production.

 

6
within each of the 5 x 10 meter plots. Each 1 M2 quadrat was sub-
divided into four 0.5 x 0.5 square meter units. Every two weeks
during the seed production period one of these 0.5 M2 plots was
selected at random from each of the twenty l M2 quadrats, and from it
all live M} lineare plants were harvested and brought to the lab for
assessing insect damage and seed production.

Since plants were harvested from these quadrats, new random
selections were made for 1965 and 1966. From the number of plants
harvested and the number of seeds released naturally on drying, an
estimate of seeds per plant per day could be obtained. In addition,
various other information such as number of capsules and plant damage
was recorded.

Plants were pulled from the plots as early in the day as pos-
sible and all individuals in each .5 square meter quadrat carefully
placed in a separate plastic bag. The sequence of harvesting the
treated and untreated areas was switched each time so that neither
area would consistently be influenced by time of day harvest was made.
The plastic bags were labeled and taken to the laboratory where the
plants were transferred to a paper bag and allowed to air-dry for 24
to 48 hours. When the plants were air-dried, they released the seeds
from the ripe capsules. (Unripe capsules do not naturally dehisce.)
After the drying, the released seeds were counted along with the number
of open capsules on each plant. The open capsules remain on the plant
and thus include all that have dispersed seed since the plant matured,

except for branches lost to predators.

7

Insect damage to the plants was also noted and described, but
in general the insect damage data were poor on these since the dry
plants break easily and damage is not easily observed. However, under
certain conditions, damage information from these plants proved useful.

Along the 10 x 10 meter perimeters 100 randomly selected
plants were examined throughout the growing season or until each died.
During 1965, data from the 100 plants were a little erratic because
lack of time made it necessary to shift from weekly to bi-weekly
observations, and a four weeks absence in mid—season left a large gap
in the observations. During 1966, data were obtained from the plants

once a month. On the central 7.62 M2 area, all Melampyrum plants were

 

counted in the late summer and again in the following spring on the
treated and untreated plots.

Pesticide treatment on the plots consisted of an application
of granular Aldrin at the rate of 2 pounds per acre. In 1965 the
Aldrin was applied in early June. In 1966 and 1967 Aldrin applica-
tion took place in late April. In addition during the summer of 1965
and 1966 weekly applications of 50 percent Malathion and 50 percent
D.D.T. were applied to the vegetative portions of the plots with a

ten gallon hand sprayer.

Insect-Melampyrum Relationships

 

A considerable amount of time was spent making observations of
the plants and looking for insects associated with the plant. Both
night and day insect behavior and activity were observed in the lab-

oratory and in the field. For night observations a flashlight proved

8
most effective, and particularly on warm nights such observations
were very productive. Many insects not found on the plants during
the day could readily be collected from them during the night. Many
of the immature insects found on lower leaf surfaces during the day
were on the upper surfaces at night and therefore more easily col-
lected.

Insect-Melampyrum relationships were studied both in the field

 

and in the laboratory. Insects collected from field populations of

Melampyrum were either caged on plants in the field or taken back to

 

the laboratory and fed on Melampyrum. When unknown insects were ob-

 

served on Melampyrum, the first step was to determine whether the

 

species would feed upon Melampyrum. This was usually done by placing

 

the insect in a cage with some leaves of the plant. If it turned out

that the insect did eat Melampyrum, then further work was conducted

 

with the species. Often after the initial determination of feeding,
the insect was moved to an outside cage if conditions permitted. If

the insect did eat Melampyrum, then a further attempt was made to see

 

what part and how much of the plant it would eat. When an immature
insect was collected, an attempt was usually made to rear it to an
adult.

Since Melampyrum lineare is a root parasite, usually on large

 

trees, it cannot be dug up and moved to the laboratory as many plants
can. The plant dies shortly after being removed from the host tree.
When insect rearing was done indoors, fresh plants had to be brought
in often. For many insects, naturally occurring plants caged in the

field worked best.

Insect Rearing Methods

Several methods were used in studying and rearing insects

associated with Melampyrum lineare. The most common rearing cage

 

used in the field consisted of a plaster—of-paris mold formed around
the base of the plant. Just as the plaster was becoming set, a lamp
globe was set into the plaster. After it solidified, a piece of fine
mesh cloth was tied over the top and the cage was ready. It worked
very well for rearing most insects and was particularly suitable for
species such as the leaf tier, which could not be moved from plant to
plant each day. This cage simulated the natural environment as close
as possible and gave fairly natural periods for life stages. For
insects which formed a pupal chamber in the soil, clean sand was
placed on top of the plaster. In such a condition the plant could
live out its normal life span and allow the insect to complete its
life cycle.

In the laboratory several methods were tried for rearing dif-
ferent insect species. The simplest method was that of placing in-
sects and leaves in a container and adding fresh leaves twice daily.
When the insect pupated, the pupa was removed and placed in an appro-
priate container, depending upon the insect.

One cage in particular worked well for rearing insects indoors.
It consisted of a pint jar 1/3 filled with a mixture of plaster—of-
paris and charcoal. A small (40 x 7 mm.) vial was placed in the
plaster mixture and the plaster allowed to set. A plant was placed

in the shell vial and the vial filled with water. Cotton was placed

10
around the stem at the top of the vial so that small insects would
not fall into the water. In this type of a container plants can be
kept for several days. This cage worked very well for rearing a
Coleoptera leaf miner from larva to adults. A container with a bottom
of plaster and charcoal worked well for rearing most pupa. When the
substrate was soaked with water and crushed leaves formed a litter,
100% of some insects could be successfully reared in this fashion.

Insects were collected from Melampyrum in many locations be—

 

sides the sample areas of the three major study sites, and occasional

observations were made in several other Melampyrum populations. In-

 

sects not found in the sampled areas were discovered in several of
these other locations. Besides collecting insects from these addi-
tional areas the plants were examined for types of damage not found
in the usual study plots. This was particularly useful for assessing
damage from different Lepidoptera larva, which appear to be general

feeders that occasionally attack Melampyrum. Many of the Lepidoptera

 

larva were collected at only one period of time and they were normally

collected from a variety of different sites.

THE ARTHROPOD FAUNA OF MELAMPYRUM

 

Approximately 53 Arthropods were found to be associated with

Melampyrum lineare in various ways (Appendix I). MDst are insects,

 

some of which are common while others were encountered only once.
Some are found on the plants only or predominantly at night, while
others were observed only or predominantly during daylight. Some

spend many days feeding on one Melampyrum plant while others are

 

found for only a short period. Some move from one plant to another
often while others spend most of their immature life on a single
plant. Some species do not use the plant for food, rather it serves
as a place to rest or a hunting ground for other animals. Whatever
an Arthropod's association with this plant species or with other
animals on the plant, it may have a direct or indirect effect on the
plants' population and becomes part of the interesting and complex
system.

Melampyrum like most plant species faces the biological

 

challenge of plant eating consumers, largely from the insect world.
In the present study insects have been observed to feed upon every
part of this plant except the root system. Most plant parts were
eaten throughout the growing season by many different insects.

Since this plant is the major non-graminoid forest floor herb
in many jack pine-oak stands, it is most likely fed upon by many
general feeders. This appears to be the case, particularly with many

11

12
Lepidoptera larva. Insects which feed upon M. lineare are known from
most of the terrestrial insect orders. Many of the orders are repre-
sented by several families which utilize different sections of the
plant. The following orders contain known insect grazers or predators

of Melampyrum: Coleoptera, Orthoptera, Lepidoptera, Hemiptera,

 

Homoptera, Hymenoptera, Thysanoptera, and Diptera; Neuroptera are
common on the plant and are probably feeding on the aphids which are
also common. In addition to the insects, certain other arthropods

are associated with Melampyrum; e.g. spiders and millipeds. Slugs

 

have also been encountered on the plant in wet periods (Cantlon,

pers. comm.).

ORTHOPTERA

Several Orthoptera show various degrees of association with

Melampyrum lineare. Basically the Orthoptera can be classified into

 

two groups. The Second group is made up of a single species,

Atlanticus testaceus, while the .first group is composed of all other

 

grasshoppers found to feed upon Melampyrum. The behavior of the non—

 

Atlanticus grasshoppers on Melampyrum appears to be distinguishable

 

 

from most individuals of Atlanticus testaceus.

 

Group One——various grasshoppers of the family Acrididae as listed in

Appendix I.

Group Two-—Atlanticus testaceus

 

Atlanticus testaceus (Orthoptera: Tettigoniidae), the shield—

 

backed katydid, appears to be the insect of greatest importance to

13

Melampyrum lineare in the study areas. The insect is brown in color

 

and fairly large.

Atlanticus appears to be a night feeder. Data taken in the

 

present study during night observations both in the field and in the
laboratory with caged feeding experiments further corroborate this

assessment. In nearly ten years of field study of Me1ampyrum popula—

 

tions grasshoppers were not found on this plant (Canton, pers. com.).
During daylight hours, the animals remain hidden among litter on the
forest floor. Although the species readily moves if disturbed in the

litter during the day, I never observed Atlanticus on Melampyrum

 

 

lineare or any other plant in the study area during the daylight in
two growing seasons of field search. As soon as darkness begins to

set in the grasshoppers can be found feeding on the Melampyrum plants.

 

During the course of several observation nights, 103 grasshoppers were

observed. Of the 103 noted, 100 were found on Melampyrum plants.

 

Two were found on the ground moving about and one was found on a plant

other than Melampyrum lineare.

 

While it was not possible to get locally collected individuals

of Atlanticus to feed on anything but Melampyrum, the species is

 

 

known to feed on other plants in habitats where Melampyrum is not

 

found. i.e., In southern lower Michigan studies indicate the species
is a more or less general feeder, eating not only plant material but
also other animals and may even be cannibalistic at times (Gangwere

1966). In areas supporting populations of Melampyrum lineare in

 

Grand Traverse county it appears that the feeding behavior of

Atlanticus differs from that described by Gangwere (1966) for

 

l4
southeastern Michigan. In the "HGQ" area this katydid feeds almost

completely upon Melampyrum, as far as plant material is concerned.

 

No observations of its predation on other animals were made. Most of
the plants named by Gangwere as food plants are uncommon or not present

in the forest sites where Melampyrum is found.

 

Gangwere (1966) lists the following as food plants of Atlanticus

 

in Livingston County, Michigan. Those of high preference were Rumex

obtusifolius, broad—leaved dock; and Taraxacum officinale, dandelion.

 

 

Those of moderate preference were: Verbascum thapsus, common mullen;

 

Berteroa incana, hoary alyssum; Daucus carota, wild carrot; and

 

 

Erigeron strigosus, daisy fleabane. These are all plants of old-

 

fields, road sides and other sunny, non-forest habitats. Twenty~two

other plants were listed as of low preference, while Asclepis syriaca

 

and Quercus velutina were rejected completely.

 

In addition to plant material, Gangwere (1966) found that

Atlanticus would also eat insects from several different orders.

 

After noting this preference of Atlanticus for Melampyrum, a

 

 

feeding preference study was set up for all grasshoppers available
using the most common plants of the ”HGQ" site. The plants were
placed in a glass jar together with one grasshopper. The grass-

hoppers were divided into two groups; group two was Atlanticus and

 

group one comprised all other species.

Fresh leaves of white oak (Quercus alba), sedge (Carex pensyl-

 

 

vanica, and low bush blueberry (vaccinium angustifolium), and

 

Melampyrum lineare were placed in the containers with the grasshoppers

 

at the beginning and end of each day. The same grasshoppers were fed

15
the same type of food throughout the experiment and observations were
recorded at feeding times.

It is interesting to note that Atlanticus would feed on nothing

 

except Melampyrum lineare (Fig. 2). The other grasshoppers fed upon

 

whatever was placed in their containers, except on occasions the sedge

was not eaten. Melampyrum lineare was eaten every time by every grass-

 

hopper and is the only plant that had this acceptance. It was ob-

served that Atlanticus would starve before feeding on anything other

 

than Melampyrum.

 

The manner in which the life cycles of the two species,

Atlanticus and Melampyrum, are synchronous with each other is most

 

 

interesting. Both nymphs of Atlanticus and green seedlings of Melam-

 

pyrum appear in late April to early May in Grand Traverse County.
The young nymphs appear as soon as the ground warms up enough to allow
hatching of the eggs (Gangwere 1966). I have found the nymphs in the

"HGQ" area in late April in 1967 and in early May in 1966. Melampyrum

 

is among the first herbs to produce fresh green tissue in the spring,
and its young seedlings are available at a time when the forest floor
has only a few overwintered green sedge leaves, a few hard evergreens

such as Arctostaphylos uva ursi and Gaultheria procumbens, and is

 

 

otherwise bare from the winter. The newly emerged nymphs start feeding

directly upon the young Melampyrum plants and often on the cotyledons.

 

It is possible that this initial almost exclusive availability of

Melampyrum in these northern areas explains the narrower food pref—

 

erence than reported by Gangwere (1966). Throughout the first part of

16

Fig. 2-—Feeding preference study of grasshoppers found in the
"HGQ" area.

 

 

 

 

 

 

m m d
.n o m
H w-i g
m a g
. g .. y. .
5 Fa : o.u
o x >. H a m
u m w o m o
m u c o .4 a
Atlanticus 5. 8 a g g :3
Days Grasshoppers
l A. - - — +
B. - - - +
2 A. - - — +
B. - - - +
3 A. died - - +
B. - - - +
4 A. - - — +
B. — — - +
5 A. - - - +
B. - - - +
6 A. — — - +
B. — — — +
Other
Grasshoppers
Days Grasshoppers
1 A. + + + +
B. + + + +
2 A. + + + +
B. + + + +
3 A. + + + +
B. + + + +
4 A. + — + +
B. + + + +
5 A. + - + +
B. + - + +
6 A. + - + +
B. + + +

* + indicates that feeding took place; - indicates that no feeding took
place.

17

the summer Atlanticus nymphs feed on the leaves, branches and ter—

 

minals of the plants. In many cases they cause extensive damage
and may kill small plants. The animals appear to be particularly fond

of the young tender leaves of the Melampyrum plants and often eat most

 

of the branch.

The branch and terminal feeding continues at an ever increasing
rate throughout June and into July as the nymphs grow. Then, as if
the katydids had left the area, this type of feeding slows, decreasing
at an accelerating rate the rest of the summer. By August, most
branch, leaf, and terminal feeding by this species has stopped. This
change can be explained in terms of changes that take place in the

Melampyrum plants and in Atlanticus feeding behavior. During the

 

 

first week in July, Melampyrum starts to produce flowers which are

 

followed shortly by young capsules. About this same time, it would

appear that Atlanticus nymphs start to molt into the adult stage.

 

The effect of these two events appears to be a marked change in the

feeding habits of Atlanticus. The katydid stops eating leaves and

 

branches of Melampyrum and now eats its seeds and capsules. This

 

change in feeding habits is neither sudden nor complete. It seems
likely that the katydids start by eating the young capsules as they

appear on the Melampyrum and over a period of time as mature seeds

 

become available, shift to a predominantly seed-eating behavior. How-
ever, even in late August at the peak of seed production, caged

animals will readily accept green parts of Malampyrum if nothing else

 

is placed in the cage. Feeding experiments showed, however, a positive

18
preference by the adult katydid for seeds over green parts during the
latter part of the summer.

The gradual change in diet of Atlanticus from green parts to

 

mostly seeds is probably due to two factors. First, the population
of nymphs slowly changes to one of adults over a period of time.

Second, Atlanticus starts out feeding on foliage plus the young cap-

 

sules before seeds are found in them. As the seed crop increases

less foliage, and more seeds are eaten. Observations strongly point

to the fact that in many cases a katydid eats only the seeds.
Individual adult katydids caged in the laboratory were observed

to feed in the following manner. Reproductive branches of Melampyrum

 

lineare containing all stages from green leaves through empty and
seed containing capsules to flowers and young terminal shoots, were
placed in the cage with the katydids. The animal would search out a
fairly mature capsule (usually with well-matured seeds) at which time
the insect, using its mouth parts, would cut a hole in the capsule.
After the hole had been cut, the seeds were removed one by one and
eaten. One seed would be removed and completely eaten before another
seed was removed from the capsule. This procedure is repeated until
all the seeds in the capsule are gone. The entire capsules are not

eaten in such cases. Atlanticus eats the part of the capsule removed

 

in the process of making the hole but does not eat any more after the
hole is large enough to remove the seeds. This type of plant damage

is common in the field populations of Melampyrum studied.

 

When freshly harvested seeds were placed with caged Atlanticus,

 

they were readily accepted and eaten. Katydids of the genus

l9

Atlanticus were kept alive for several weeks on nothing but mature

 

seeds of Melampyrum lineare. From the ready acceptance by Atlanticus

 

 

of seeds placed on the floor of the cage in the laboratory, I would

expect that this katydid eats Melampyrum seed freshly fallen to the

 

litter. The fact that these animals spend the daylight hours hidden
in the forest floor may increase the likelihood that freshly dropped
seeds would be eaten. This leads to another conjecture not confirmed

by field observation; i.e., the possibility that during the late

 

summer and early fall, Atlanticus may live mostly on new_M. lineare
seeds in the forest floor. Along in September the katydids are no

longer found at night on the still abundant and seed—charged Melampyrum

 

plants, but occur on shrubs and small trees and are singing. The
nights are cooler, and perhaps the animals feed on seeds in the litter
of the forest floor at various times of the day if they feed at all.
After the middle of August, loss of branches and terminals by

Melampyrum is almost zero, and only a small loss of leaves occurs.

 

This small amount of feeding can probably be attributed to other in-
sects.

The change in the feeding habits of Atlanticus may be responsi-

 

ble for the changes in slope of the curves showing damage to Melampyrum

 

in (Fig. 3). Between 22 June and 6 July, a period of 14 days, about
62% of feeding on branches took place during 1965 in the ”HGQ" plot.
During the next 36 days, only an additional 25% occurred. The rest of
the feeding is divided between the remainder of the summer and what
took place before 22 June. Field observations support the conclusion

that most of this feeding can be attributed to grasshopper feeding

\

20

Fig.5-- Insects feeding on Melampyrum branches for
100 randomly locattd plants in treated and untreated plots.

l965;""127" plot

 

 

 

 

 

g 60
: ." Untreated
0 /
E 45 .
O
G
(6
B
‘“ 25 To
0 ’1‘. 'IIIIWIIQ'I‘. Treated
H O
m 10
"a” o
:3
z o
200' 1965--—"HGQ" plot. Untreated
Afi 4".
o"””
G
0
’8 150
0
0) O
4)
£1
0
£3
E’.
13 100
k
‘H
O
0
'3 . _
g 50 Treated
_- 0 '4'... Ilflll'lla Q“ Q VIIIIA O
‘0
22 I 6 22

lline luly “Aug 3;“

21

and particularly to Atlanticus. Although some Lepidoptera larvae

 

feeding occurred in June, the kind of damage shown (Fig. 1) would not
include much of this. Further, the Lepidoptera larvae were not common
enough in the study sites to produce a major portion of these damage

symptoms.

COLEOPTERA

Bruchidae, Acanthoscelides sp.

 

A single species of the genus, Acanthoscelides, family Bruchidae,

 

is associated with Melampyrum lineare. The beetle is found on

 

Melampyrum during August. Several individuals were collected on

 

12 August. The insect was noted in the ”HGQ" area for only a short
time, during which it was not uncommon on the plant. The insect is a
small beetle, solid blue-black in color, and is 2—2.5 mm in size. The
insect appeared always to be near the terminal portion of the plant
associated with the flowers and was observed on different occasions

to crawl into the flowers of Melampyrum. The species is a strong

 

flyer, and when its capture was attempted in the field, it would

vanish from the flower, making it difficult to collect by hand. It
did not show up in sweepings. While associated with the flower the
species was never observed to feed upon the flower or damage it in

any way.

Curculionidae, Panscopus sp.

Panscopus maculosus was not often collected, and all collec-

 

tions of the species were made with the use of a flashlight at night

22
in the ”HGQ" area. The adult beetle is probably nocturnal in habit
and hides during the day.

The insect was found moving over the Melampyrum plants and

 

feeding on the leaves. Caged specimens would readily feed on the

leaves of Melampyrum lineare, consuming most of the leaf in some cases,

 

while in others eating only small portions.
The insect is solid brown and of moderate size. It looks
typically like a curculionidae.

Collecting records were from late June 1965.

Conotrachelus posticalus

 

TWO Specimens of this insect were collected from Melampyrum

 

lineare in the "HGQ” untreated plots on 8 July, 1965 about 10:00 p.m.
The specimens were moving about on a group of plants but were not

feeding and did not eat Melampyrum lineare in the laboratory. No

 

other individuals were observed.

Acalyptus curpins

 

A very small individual was collected from a Melampyrum plant

 

on 24 June 1966 in the ”HGQ” area. It was not observed to feed on

the plant.

Lathridiidae

Large numbers of these beetles were collected from plants
pulled by Dr. Cantlon on 14 Septemper 1966 from near the 127 plots.
Individual plants were pulled, placed immediately in plastic bags,
and carried back to the laboratory. There the plants were spread

out for air drying. Many of these small beetles were observed

23
crawling on the plants and over the paper-covered laboratory bench

on which the plants were drying.

Derodontidae

One specimen was collected while sweeping Melampyrum plants

 

near the "HGQ” plot with an insect net.

Chrysomelidae
Three species of beetles from this family are found associated

with Melampyrum lineare. Two of the species, Disonycha sp. and

 

Dibolia boralis are fairly common and are known to feed on Melampyrum

 

 

in both larva and adult stages. The third species Microrhopala xerere

 

was collected only once on the plant in the area of M10, Michigan and

was not observed to feed on the Melampyrum lineare.

 

Disonycha sp.
Disonycha sp. is a moderate sized (5—6 mm long) beetle which
is oblong-oval and convex. The species of this genus which is found

on Melampyrum lineare has a solid dark colored elytra, black or blue-

 

black. The pronotum is orange or yellow with a black marking which
somewhat looks like the letter ”M”. Adults are found early in Spring
and then again in August. Larvae are found during July and early
August.

It would appear that the adult stage over’winters. I have col—
lected adult beetles as early as May in the "HGQ” area. Eggs are
probably laid in June. Larvae can readily be found during July on the

leaves of Melampyrum lineare.

 

24

On July 7, 1965 three larvae of Disonycha sp. were collected
and placed on a caged plant in the field. The larva fed for several
days and then formed pupal chambers in the sand which had been placed
on the cage floor. On August 23, 1965 the adults were observed in the
cage feeding on the leaves. Both adults and larvae are leaf feeders.
The larvae were most easily collected at night when they were on the
upper surfaces of the leaves and moving about. They remained on the
under side of the leaves during the daylight hours, except on cloudy
days when they were collected from the upper leaf surfaces. Feeding
damage to the leaf, consisting of holes chewed in the leaves, can
readily be spotted during the day and the insect collected from the
underside. The larvae were usually found in groups. When disturbed,
the larvae and adults often drop from the leaf and become hidden in
the ground litter.

On 8 July several larval specimens of this species were col—

lected from Melampyrum plants at T18N?R6W-Sec. 34 in Clare County.

 

Dibolia borealis (Chrysomelidae) is a small dark—colored beetle which

 

is commonly found on Melampyrum lineare and most difficult to hand—

 

collect. The insect, while perhaps not of any great importance to

the over-all population of Melampyrum lineare, can in isolated spots

 

cause fairly extensive damage and in some cases, materially contribute
to the death of individual plants.

Both larvae and adults attack Melampyrum lineare and can do

 

equal damage. The adult is an external feeder most common on the more
tender leaves at terminal and branch ends. Its feeding consists of

many holes eaten in the leaf, and under heavy feeding of several

25
beetles, the holes run together, leaving the leaf well out up. Since
adults are most common near the terminal parts of plants, damage to
immature buds and seed producing parts is common.

The larva, on the other hand, lives in the leaf as a leaf
miner. When the larvae are young, they appear to remain inside a
single leaf for several days or longer. By the last instar, larva are
fairly large and move from one leaf to another more frequently. Some
plants with one or two miners may have many of their leaves eaten.
During late instars, larvae are found inside and on the surfaces of
leaves with about equal frequency, and they appear to move from plant
to plant more often. Where plants touch each other, there appears to
be no hesitation about moving to a new plant. I observed nothing that
suggests that the larvae normally move over the forest floor to new
plants. However, if dislodged, they crawl around on the forest litter
until they encounter a plant and then crawl up to a leaf.

Adult beetles are found in early spring. It appears that the
eggs are layed in early summer. The young white larvae appear in June.
The later instars move freely over the plant and from time to time cut
a hole in the leaf epidermis, mine for a while, and then come out and
move to another leaf. The final instar is colored a light yellow, and
can easily be distinguished from the early stages.

It would appear that in some cases, the late instar larvae move
and feed in a group. At times, five or six larvae would be found on
a single leaf or on nearby leaves of the same plant. By feeding in a
group, they soon completely destroyed the leaf, after which they moved

to a new feeding site. Such late instar behavior destroyed most of

26
the leaves on some plants at various places in the study sites, but
severe damage was not general in any of the areas.

When the larvae are mature and ready to form pupae, they move
to the ground and form pupal chambers in the soil. In the laboratory,
it was observed that the compactness or hardness of the soil would be
unlikely to deter these larva from pupating. TWO larvae were ready
to form pupae before I added soil to the charcoal and plaster-of-
paris base of the cage. Both attempted to form pupal chambers in the
plaster-of—paris and one became half buried in this hard material.
When sand was added over the hard substrate, the larvae formed pupae
in the sand.

The pupal stage lasts about 15 days. One group that was ob-
served closely formed pupae on the 28th and 29th of June. The first
adults emerged on the 13th of July, and the rest emerged the following

day. Upon emerging, the adults moved directly to the Melampyrum

 

lineare plants in the cage and began feeding on leaves near the ter—
minal. Apparently the adults are fairly long lived and feed for quite
a period of time. In the laboratory, the above insects fed upon

Melampyrum lineare for three weeks before being placed in alcohol.

 

It seems possible that the insect could complete two cycles in
a year, but perhaps it does not. Dilion and Dilion (1961) state that
this beetle spends the winter as an adult under bark of sycamores.
All the literature concerning these insects indicates that they are
miners in Platanus leaves. Sycamores are not found near any of the

study areas. The adults could spend the winter under bark of pines or

27
forest floor debris. The adult beetles can be found throughout the
second half of the summer.

Egg laying in the spring must vary greatly because larvae are
found over a long period of time and in different stages. Larval
populations appear to reach a peak near the end of June. It is in-
teresting that adults of this insect were collected all summer long
from the first of June until the last part of August. Adult specimens
were even collected in late June at the peak of larval production. It
is possible that more than one stage over-winters and that there is
more or less continous reproduction, with a peak reached in mid-

summer.

Coccinellidae, Hyperaspis sp.

 

Hyperaspis sp. is a small, oval, black Coccinellid, having the

 

elytra spotted with yellowish marking. The insects were not found on

Melampyrum lineare except at Mio, Michigan, on 5 July, 1966 where the

 

beetles were fairly common on the plants. The insects were not ob-
served to feed on the plants. They moved rapidly over the plants and

appeared to be looking for insects to feed upon.

Alleculidae, Isomira sp.

Isomira sp. was collected from Me1ampyrum lineare only twice.

 

The beetles have been reported by Dilion and Dilion (1961) on flowers
and this may have been the explanation for their presence on

Melampyrum on the 7 July 1965 at the ”HGQ” site.

 

28

Elateridae, Limonius basillaris

 

The family Elateridae is found to be associated with Melampyrum
as larva and adults. Toward the fall of the year, Elaterid larva have
been found to eat the plant's seeds in the forest litter. On dif-
ferent occasions, individuals have been found with half eaten seeds.

Limonius basillaris is a small Elaterid found abundantly around

 

the "HGQ" site. The adults vary in length from 5-5.5 mm. Dilion and
Dilion (1961) describe them as black, with sparse grayish pubescence
and with reddish yellow legs. Their second and third antennal segments
are short, with their combined length not equaling that of the fourth
segment. The elytral striae are deeply punctate.

The beetles are usually reported on oak, which probably explains
their presence in the ”HGQ” plots. The beetles are often found
crawling over the plants but appear to be particularly active near the
flowers; and have on two occasions been observed to eat parts of

Melampyrum lineare flowers.

 

Scarabaeidae
TWO genera of Scarabaeids (Serica and Phyllophaga) were found

to feed on the leaves of Melampyrum lineare in the adult stage. Both

 

of these genera are night feeders and were not seen during the daylight.
0f the two genera Serica sp. was the most common and was found in the

largest numbers on Melampyrum plants. Extremely large numbers of

 

Serica sp. were collected at a black light when it was run near the

"HGQ" plot. Phyllophaga sp. was also found on Melampyrum and on

 

29
July 8, 1966, individuals of both species were collected from

Melampyrum at the same site during night observations.

 

Serica sp.
Serica sp. is a rather small Scarab type beetle. The beetle

looks much like a small May beetle (Phyllophaga) from which it can be

 

distinguished by its regularly spaced elytral striae and its smaller
size.
Serica sp. is a leaf feeder and for a period of time is fairly

common on Melampyrum plants. During night observations, the beetles

 

were noted to feed on the leaves of the plants. The species was most
common during the last part of June and the first of July. During the
daylight hours these beetles hide beneath logs and other forest debris.

They emerge from hiding shortly after dark and start feeding.

Phyllophaga sp.

 

Phyllophaga sp. are the beetles commonly known as ”June bugs"

 

or ”May beetles." While not extremely common, adult beetles were

found during night observations to be feeding on the leafy tissue of

Melampyrum lineare.

 

The beetles appear to restrict their feeding to the leaves,
but are able to inflict fair amounts of damage. Large plants had
leaves eaten off by the beetles and often more than one insect would

be found on a plant. Both Phyllophaga and Serica were noted feeding

 

on blueberries and are general feeders not restricted to Melampyrum.

 

30

Carabidae

Carabids, particularly Synuchus impunctatous and to a lesser

 

degree Calathus sp., form batches (”caches" of Cantlon, Curtis &

Malcolm, 1964) of mature Melampyrum seeds among the litter material

 

of the forest floor or under logs. The seeds, after being discharged
from the plant, are picked up from the forest floor by the beetles
and carried to these clusters.

While it might seem likely that this type of "cacheing" activity
would be for the purpose of food storage the opposite appears to be
the case. The seed piles might more nearly be compared to refuse
heaps. The only part of the seed eaten by the beetle is the soft,
spongy caruncle at the seed base. The remainder of the undamaged
seed is discarded at these particular points.

While natural field observations of this activity have not been
possible because of the depth and continuity of the litter and the
furtive behavior of the beetle, laboratory experiments have been
successful. The insect has been observed building seed caches of up
to 50 seeds. Apparently, the carabid moves slowly over and through
the forest floor in search of food. When contact is made with a

Melampyrum seed, the mouth parts grasp the caruncle end and the seed

 

is carried to its hiding place. There, the caruncle is eaten from
the seed, discarding the intact remainder at the same location. After
the caruncle is eaten, the beetle leaves its lair and searches for
another seed. This activity may be repeated a number of times before

the insect will rest. Once the caruncle is eaten, the beetle appears

31
to have no more interest in the seed, which becomes part of the refuse
heap.

It appears necessary for the carabid to come in actual contact
with the seed before it is noticed. Seed abundance and carabid activity
appear to determine the size and distribution of seed clusters. The
caruncle must be present on the seed or the carabid will do nothing
with it. The carabid appears to pick only seeds with caruncles for
two reasons. First, the caruncle is the edible part of the seed for
these insects. Second, the beetle does not appear to be able to grasp
the seed after the caruncle is gone. Laboratory experiment indicates
that when a beetle comes in contact with a seed from which the caruncle
is missing, the seed will be pushed around a bit and a search made for
the caruncle, but if not soon found, the insect will give up and go
about looking for another.

Seeds are of significance to the carabid for only a brief
period after being discharged from the plant. The caruncle does not
remain on the seed very long after it reaches the forest floor.
Microorganisms attack this part of the seed quite soon if moisture
is available and within a few days it has disappeared. Also, other
macroscopic organisms appear to eat the caruncles, e.g., millipeds,
which are abundant at the ”HGQ” site in fall, have been found to eat
large numbers of caruncles under caged conditions. They do not aggre-
gate the seeds the way carabids do but eat the caruncles and leave
the seed where they encounter it. It would appear that carabids are
fairly effective seed collectors. In the "HGQ" area, almost all the

Melampyrum seeds are so clustered. For this to occur, the carabid or

 

32

some organism with similar seed aggregating behavior would have to
get to the seed before any other organism removed the caruncles.

Seed aggregating is interesting to watch. While the beetle is
searching, it moves slowly looking for food. When a seed is found,
the entire mood of the insect appears to change. The beetles' rate
of activity greatly increases. Its movements which were slow while
the insect was looking, become very rapid and it appears to run as
fast as possible to its place of hiding with the seed. The increase
in activity rate produces a striking contrast to its earlier pace.

Four species of carabidae are common in the plot areas.

Yrigonognatha, Bothriopterus, Synuchus and Calathus. Synuchus and

 

 

Calathus have been observed to eat caruncles and move seeds. Synuchus
is of particular interest since it appears to be the most common
during the time that seeds are being released from the plants and it
appears to have the strongest tendency to aggregate seeds in large
numbers at a particular spot.

For the purpose of watching insect seed aggregation behavior in
the laboratory, two methods were used. In the first method a 12” x 6”
rectangular metal pan was used. The pan's bottom was filled with a
couple inches of soil and one piece of bark and wood was placed on the
soil in the dish. Three carabid beetles were placed in the dish and
seeds scattered around on the soil.

Soon, seed batches began to show up and as time progressed,
they continued to grow larger. MDre seeds were added as the ones
placed in the cage were carried out of sight. Seed batches found

in the dish looked very much like those found in the field. While

Total number of beetles

Percent number of beetles of each species

 

33

Fig.4-- Carabid beetles collected in pit traps

in all plots in 1905.
,////S;huchus impuntatous

 

 

 

‘20
Pterostichus sp.
IO
5 \\ Calathus sp.
\ /'.,.—0
"‘K
\\

8O Synuchus impuntatous

Pterostichus sp.

\\
“\
*3

 

30

lune Isuly A112

2-

a 2
Sept

34
this set-up was fairly natural and worked well for getting batches it
was hard to keep track of the beetles and every time the wood was
picked up, the insects were disturbed. It appeared that after a while
the beetles stopped using the under—the—wood site and began to hide
seeds in holes in the soil instead.

Another method was a variation of the first and consisted of
the same dish, but the bottom was covered with a mixture of plaster-
of-paris and charcoal which made a hard surface. On this substance
was placed a single piece of bark, one carabid beetle, and several
seeds. This method worked well and the beetle went right to work
building a seed batch. All the seeds placed in the container could
be kept track of as well as the beetle. Also the bark could be lifted
up without disturbing the seeds greatly.

Most all of the seeds placed in the cage were carried under the
bark and their caruncles eaten. The beetle remained under the bark
with the seeds except when it was out hunting for others. The beetle

was fed nothing but Malampyrum seeds for several weeks and appeared

 

to remain healthy. Many seeds were aggregated during this time.

In these experiments, not all seeds were aggregated. Occasion—
ally the insect would eat the caruncle from the seed without taking it
to the hiding place. However, most seeds were carried back under the

bark where their caruncles were eaten.

LEPIDOPTERA

While several lepidoptera larvae are known to feed on Melampyrum

 

lineare, none were found commonly enough to do damage over a wide area.

35
Many of the lepidoptera larvae were collected only once or twice
during the two summers of the study. The exception to this was

Sparenaothis reticulatana, a leaf tier on Melampyrum lineare, which

 

 

was common and easily collected almost anywhere that Melampyrum

 

occurs.
Some Lepidoptera pupae were collected in the field from

Melampyrum the adults of which were identified. It is not known

 

whether the larva of these species feed on Melampyrum or whether they

 

happened just by chance to pick the plant for pupation.

Spareanothis reticulatana

 

Sparenaothis reticulatana is a small, yellow-colored moth. It

 

is the most common species of lepidoptera found on Melampyrum lineare.

 

The larvae are common and easily collected. Often the larva webs

together two or even three young branches. It lives inside this nest

where it feeds on the plant; frequently destroying the branches.
Several individuals of this species were raised through to

adults on living plants of Melampyrum lineare caged in the field.

 

The larvae of the species can be collected throughout June. By the
last of June and early July, the larvae are starting to transform into
pupae. The pupa is formed within the mass of leaves pulled together
by the larva. Just prior to the onset of pupa formation much more
webbing is added to the inside of the nest and a tight cocoon-like
structure is formed around the pupa.

Individuals raised on caged plants emerged as adults near the
middle of July. The first one emerged on July 15 and the others

shortly after.

36

Also observed is a larva which lives in the stem of Melampyrum,

 

and which appears to be Sparenaothis reticulatana. None were raised

 

to adults for positive identification. The larva destroys the ter-

minal of the plant.

Abbottana clemataria

 

This is a typical moth of the family Geometridae. It was
described by Forbes as follows: "The adult is brown on a gray-
colored clay base, irregularly shaded and mottled. Both the ground
and the markings vary greatly in shade of color. Discal dot black,
fine. 45-60 mm., female larger.”

Two larvae were collected during the summer of 1966 and raised
to pupae. One was collected as a very small larva (10 mm.) near Mio,

Michigan on 5 July 1966. This individual was fed Melampyrum until it

 

formed a pupa in early September. The pupa was placed among crushed
leaves and kept moist outdoors throughout the fall. In late NOvember,
it was brought into the laboratory and pieces of ice added occasionally
for moisture. The adult emerged in early January.

The other larva were found crawling over the ground near the
"HGQ” site. It was placed in a cage indoors and soon formed a pupa

which died.

Papaipema sp., Noctuidae
Only one larva of this insect was collected and it was not

raised through to an adult. The larva was found on a Melampyrum

 

plant on 2 July 1966 near Mio, Michigan. It was taken back to the

laboratory and fed on Melampyrum lineare for about three weeks. The

 

37

feeding of this lepidoptera larva was unlike that of other lepidoptera
collected. Feeding always started from the center of the leaf. A
hole would be cut in the leaf and then enlarged. After feeding in
that spot, the animal would stop. When feeding resumed, a new hole
would be cut in the leaf.

The specimen belongs to a large genus and according to Forbes,
many of the Species are host Specific. The larva are said to mature

from July to September. The one collected from Melampyrum was pre—

 

served as a specimen before pupating.

Anacamptodes humaria Geometridae

 

A single larva of this genus was collected from Melampyrum

 

lineare on the 7th of July 1966 in Grand Traverse county.
A group of plants showed signs of considerable damage. After
some looking, the above larva was found. It was taken back to the

laboratory and fed on fresh Melampyrum leaves twice daily until

 

18 July 1966, at which time it formed a pupa. The pupa was placed
on wet sand and covered with crushed leaves. The adult emerged on

26 July 1966.

Autographa epigaea Noctuidae

 

Autographa gpigeae was first collected from Melampyrum lineare

 

 

on 16 June 1965 near the "HGQ” plot. The larva was large, green

and had a smooth skin. It was discovered feeding on Melampyrum at

 

10:00 a.m. and in the immediate vicinity, several other plants were

found which had the terminals eaten off and many leaves eaten. The

38
damage was typical of this insect and most of the plants were almost
completely destroyed.

The larva fed readily on Melampyrum leaves when placed in a jar.

 

On 17 June 1965, the larva was placed outside on a caged plant. After
a few hours of feeding, all the leaves along with the terminal were
eaten off. At 1:30 p.m. on the 18th of June, the larva was moved to

a new plant which had 9 leaves plus two small ones at the terminal.

At 8:00 a.m. on the 19th of June, the larva had eaten all but 11 cm.
of bare stem. During the afternoon of 19 July, after the larva had
moved to a third plant, it stopped eating and started to pull the top
leaves together with strands of Silk.

At 9:30 a.m. on June 20, the larva was busy covering itself
with silk, but was not yet completely enclosed. The larva kept working
until completely enclosed and then lay still in the cocoon for several
days. On 7 July, a green pupa was noted inside of the cocoon. This
green pupa later turned brown. On August 19, 1965, it was observed
that the adult had emerged.

The larva of this species was found on Melampyrum lineare only

 

once during the two year study. It is a vigorous feeder and consumed
almost the entire plant. The larvae are commonly found on jack pine

in the area, but appear to feed only infrequently on Melampyrum. It

 

appears to be one of the few insects outside of the katydids that can

kill vigorous young plants.

Pupa only:

Four species of insect pupae were found associated with

39

Melampyrum lineare. It is not known whether the larvae feed on

 

Melampyrum or not.

 

They are:

Archips rosaceana Harris

 

Eubaphe auranticaca Hfibner

 

Xanthotype urticaria Swett - spreading wings on plant just
after emergence

 

Archips argyrospila Walker

 

Larva only:
In addition to the larvae which were raised through to adults

several other immature Lepidoptera were collected on Melampyrum, and

 

fed on it for some time without successfully developing into adults.

Mbst Of these were either NOctuidae or Geometridae.

Noctuidae
1. TWO individuals were collected 21 July 1966 near the 127 plots on

plants that were part of good populations Of Melampyrum. These were

 

fed on the Melampyrum leaves in the laboratory. However, both larvae

 

contained Tachinid parasites and could not be raised through to adults.
2. Collected in the litter near the 131 plots was a seed eating
Lepidoptera larva. Several Of the insects were collected. In all
cases they were collected in the litter near or with small batches Of

Melampyrum seeds. Whether the larva actually aggregated the seeds or

 

took advantage Of existing aggregations is not known. Partially eaten
seeds were found and the larva appeared to have been staying with the
batch for some time as suggested by a large amount Of frass associated

with the larvae and seed sites. In addition to those batches

40
harboring a larva, other batches were Observed which contained a
large amount of frass but no larvae. Specimens were collected on
11 September 1965.
3. Several times around the 14th of September, 1965, capsules were
collected from the "HGQ" untreated plot which contained a small
Noctuid larva inside of the capsule. The small larvae were seed
eaters and in capsules which contained these insects, seeds were
destroyed in varying degrees. In the extreme cases, brown frass re-
placed the seeds completely. It is not known whether the insect com-
pletes its cycle in one capsule, if it moves from one to another, or
where it spends the winter.

4. A small green noctuid larva was collected twice from Malampyrum

 

lineare. The first was collected on 24 June 1965 but was parasitized
and could not be reared through to adult. The second collection was
made on 5 July 1966, and the adult emerged on 14 July from a pupa
formed on 7 July. Unfortunately the adult escaped. I have the pupa
but not the adult.

5. On 6 July a brown colored Noctuid was collected from Melampyrum

 

lineare in Grand Traverse county. The larva measured 32 mm. long and

fed on Melampyrum in the laboratory. It was not reared to an adult.

 

Geometridae
1. During the latter part of the summer many small geometrid larva
appeared on the plants. Collections of these larva were made from

14 August to 13 September.

41

HEMIPTERA

Two families of Hemiptera were observed feeding on Melampyrum

 

lineare. The two families are Pentatomidae and Corimelaenidae.

Pentatomidae is represented by the genus Euschistus sp. and Cori-

 

melaenidae by Corimelaena sp. Both species are found during July

 

and August.

The insects were observed feeding on the plant's juices from
the stem, capsules, and seeds, in particular from the capsules.
Hemiptera were Observed on the plants both at night and during the
day and appear to feed both times.

Corimelaena, a black-colored bug, feeds on the capsules in the

 

following manner. The beak is inserted through the capsule wall into
an immature seed, the juices of which are sucked out. After feeding,
the bug moves and repeats the operation on a new seed. As a result
of this feeding, the capsule and seeds appear shriveled. Capsules
which had been fed upon were opened and examined in the laboratory
under a microscope. Holes were found passing through the capsule
wall and into the seeds. It appeared that the inside of the seed had
been sucked out. A hole was also found in the seed.

In the field it is not uncommon to find one or two seeds in

capsules of Melampyrum that are shriveled up and hard. This could

 

well be the result of past feeding by this insect. Often field popu-
lations Show capsules in which the seeds are black and dried up. Seeds
in this condition have been shown to contain a fungus. It seems quite

possible that Corimelaena sp. is responsible for the wounds and

 

42
perhaps even for the innoculum of fungi inside the capsule. Seeds
collected from litter frequently have small black spots on their
otherwise golden brown exterior (Cantlon, 1967). It is possible that

feeding by Corimelaena or some similar insect may be responsible.

NEUROPTERA

During the summer several specimens Of Chrysopa, family

Chrysopidae were collected from Melampyrum lineare. The specimens

 

appear to be Chrysgpa oculata. TWO specimens collected on 14 September
were covered dorsally with a shell made up Of debris. The shell con-
tained a great many things cemented together with what appeared to be
body secretion of the animal. Some of the debris found on the animal
included the following: small chunks Of dirt, plant parts, many

legs, heads and other insect parts, whole aphids, and oribatid mites.
Some Of the plants from which the Chrysopa were collected contained
large numbers Of aphids and it seems likely that the insect was

feeding on them.

THYSANOPTERA

Thysanoptera appear to be fairly common on the plants. When
freshly pulled green plants were heated in a berlese funnel, many Of

these animals were collected.

HOMOPTERA

By August in both years, aphid populations in some areas had

reached large numbers. Populations, however, appeared to be very

43
spotty. The insects would be very common on a small group of plants
and a few feet away no aphids could be found. Populations appeared

to be heaviest in the 127 plots.

HYMENOPTERA

One specimen Of Tenthredinidae was collected from Melampyrum

 

lineare on 2 July 1966 near Mio, Michigan. It was taken back to the
laboratory and fed on the plant for some time but was not raised to

an adult.

Formicidae
Ants are perhaps the single most common kind Of insect found

on Melampyrum. No direct relationship has been found between the

 

ants and Melampyrum injury. Ants move over the plant and cover a

 

great deal of its surface area. Most of their time is spent carefully
patrolling the leaves with their head close to and their antennae
constantly tapping the leaf surface. Every SO Often, the ant will
come to a stop and appear to feed. The ants could be getting plant
juices from the tips of the glandular hairs or through wounds caused
by other insects. Second, they may simply be using the plant as a
hunting ground for Thysanoptera and mites.

Since information from an earlier study (Curtis and Cantlon

1965) had suggested that ants might be of importance to Melampyrum

 

populations, considerable time was spent watching ants on this plant.
NO visible damage appeared to be caused by the activities of ants

described above. Ant presence on this plant species does not appear

44
to be related to the presence of aphids. The ants appear neither to
be interested in aphids they encounter, nor are they more abundant on
plants with aphids. Further, ants are found on the plants in the
spring, summer and fall of the growing season.
Ants caged in the laboratory for considerable periods showed

no interest in Melampyrum seeds provided them.

 

ARANEIDA

Spiders, while apparently not directly harmful to Melampyrum,

 

are common and abundant on the plant, where they appear to feed upon
insects. Families found are Salticidae, Thomisidae, and Araneidae.

Thomisids are most commonly found on Melampyrum. The spiders

 

are often seen apparently waiting for insects near terminal portions
of the plant where the leaves are thicker. They appear very fond of
ants, and the most common Thomisidae is Often observed with an ant in
its grasp. Araneidae,while not abundant, can often be found. Very
small spiders of this family build webs between branches or more
commonly among the terminal leaves.

Salticids are often seen running over the plants in search of
food. They are particularly common during the first part of the

summer .

VERTEBRATES

Chipmunks--Damage to capsules by chipmunk chewing was Observed
and in some cases, these mammals were Observed to be the predator

responsible for missing capsules.

RESULTS AND DISCUSSION

Melampyrum lineare populations can be inventoried accurately

 

from the green, emerging cotyledons of late April seedlings through
the blooming and seed producing plants Of late summer and into
autumn. Some mortality occurs throughout this period and all indi-
viduals of this annual plant are dead by late October. The potential
population for the next year exists in the seeds that reach the
forest litter. In late fall the forest floor seed population is
largely from the preceding growing season but depending on the rela-
tive production and dormancy percentages it also includes seeds from
earlier years (Cantlon, Curtis and Malcolm 1963; Curtis and Cantlon
1968). Thus insects could reduce the plant's population by eating
young plants, grazing on potential seed bearing tissue of older plants
and by preying on seeds on the plants or in the litter. It was be-

lieved that a comparison of the number of Melampyrum plants in these

 

various life cycle states between pesticide treated and untreated
control plots should yield a minimal estimate of the impact of the
pesticide-sensitive organisms on this species.

Experimental Studies with Field Populations
of Melampyrum

 

Melampyrum seedlings in populations studied over a two year

 

period indicate that pesticide—treated plots tend to increase in
numbers over untreated controls.

45

46
Spring seedling counts followed by late summer harvesting Of
mature plants for seed production estimates were made from the one
meter square plots. These inventories added some interesting and

important information to the Melampyrum picture.

 

The major influence Of treatment with insecticides appeared

to be that treatment released the Melampyrum population from its

 

arthropod checks and allowed the population to increase at a more
vigorous rate than it had under normal conditions. Since each plot
has its own characteristics, each will be discussed separately.

The ”HGQ” plots showed a most dramatic population switch after
treatment (Figs. 5, 6, 11). If the first counts made in July 1965
were projected back to May, the untreated plots would contain five
times as many M. lineare seedlings as the treated area. By 1966,
after one year of pesticide treatment, the treated plot had 1.6 times
more plants than the untreated. The 1967 counts showed the treated
area to contain 3.8 times as many plants as the untreated. In total,
the treated population had grown 8.8 times that of the untreated area.
In the untreated, the population size dropped at a steady rate. In
the treated plot, insecticide application pushed the population to a
high in 1966 and held it at a relatively high level in 1967 when com-
pared to the untreated area.

The "127” plots reached the highest populations, but in this
area the treated plots started out 2.5 times higher than the untreated

area in 1965 (Figs. 7, 8, 11). In the untreated plots, the Melampyrum

 

populations remained fairly constant. It would appear that in this

area Melampyrum and insects have maintained a good natural balance.

 

 

 

 

 

 

 

 

.“ “ " W?“ ' ""T‘“'”' “ "‘ “7...“. "' T *‘f"‘“‘ "T" "" 7': : l . 1

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.__.1.numb¢r of Melampyrum plants On July 25, 1965 and H.1M.-WNH

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£11..1. Fig. 6-— Replicated survivorship curves shcwing ..-..1 A
§;--~.number of Melampyrum plants on May 11,1966 and ;_--111111

’

 

numbers surviving until harvest_ at two—weekly ' f‘ " ;O
i

 

T“ r—“1

’Jntervals after seed prOduction began ( August 2 l960)
-_.-_ for a five meter square area in the "HGQ" plot. -11-11111

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'plants alive

 

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111F1g.7-- Replicated survivorship curves1showing1_
number 6f melampyrUm plants -on JuIy 25“, I965 and11111111_
numbers sur_Viving until harvest at twoeweekly "
. .Lintervals after segd production began ( August 3V
111111£or a five meter square area in the "127"-1plot.;1.111111_1

 

 

 

 

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50

J-..

' I
1.... .1 _u—o

.Wf.number of Melampyrum plants on Ifiay 11, I966 and , ‘T't‘
-[numbers surviving until harvest at twoeweekiy I-:I_i1' ._;
‘intervals after seed production began ( August 2,1966)

Jor a five meter square area i.n the "127" plot.

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11 gq.numbers of Melampyrum plants on July 25,11955 and _g

._ 11.1.1

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_ MAY ‘ JUNL JULY AUGUoT SEPT.
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_» _fnumbers surv1v1ng until harvest at two-weegly

 

___... __H __ __ ._ ___...

intervals after see:d pr6ductien began ( August 5, 1905)
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11111Ifor a fiVe meter square area in the

plants alive

Number of

H.———-.- . .—_. fi———-—~
-._ .__.. ....., —. ___. .1 _
h- — - —. _ - ..._._._

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.11iFig. lO—- Replioated surVivorship curves showing --1
inumber of Melampyrum plants on May 11,1966 and : .11
numbers surviving until harvest at two-weekly ‘ "

-1_.__._ -.-

I intervals after seed production began ( August 2,1966)

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67

 

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I
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?

 

 

 

 

 

 

ated spring1counts
_rorzé;r

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i
WWW--.....W—WW1 _

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l

 

 

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54

The pesticide treatment drastically reduced insect predation on the
_g. lineare population and it responded with a very large increase in
numbers. The treated plots in the "127" area had an estimated 2.5
times more seedlings than the untreated plots in 1965 but the dif-
ference increased to 8.6 times more seedlings in the pesticide plot
in 1967.

The "131” plot (Figs. 9, 10, ll) differed from the other two
areas. Plant population estimates from projecting the survivorship
curves back to May indicate that the treated area may have started

out in 1965 with a Melampyrum seedling population which was as much

 

as 2.5 times smaller on the treated than on the untreated plot. In
1966 the actual spring seedling counts on the two plots at "131”
indicated essentially the same numbers. If the 1965 estimates were
correct the treated populations increased and the plant inventories
converged in a pattern similar to the other areas. The 1967 seedling
populations were essentially the same on the treated and the untreated
areas. This would suggest that these populations are limited by
something other than pesticide sensitive arthropods. In all the plots
the 1967 spring seedling estimates are minimal since they were made

in quadrats from which seed—bearing plants had been harvested in 1966

at four intervals as described in the methods and materials section.

Arthropod Influence on Melampyrum

 

The increase in Melampyrum population sizes in insecticide

 

treated plots could indicate that their numbers are held in check,

at least partly, by pesticide sensitive organisms. Inadequate

55
replication in this study makes it impossible to assert this was the
case, but other studies (Cantlon §t_§l, 1968) and my own observations
are strongly suggestive that this is true. The numbers of invertebrate
species on these sites that would be expected to be pesticide sensitive
is very large and observations were concentrated on those Arthropods
that were actually found on the plants or suspected of feeding on

Melampyrum seeds in the litter. Of the 53 species observed, the one

 

most likely to exert the strongest influence is the shield—backed

Katydid, Atlanticus testaceus. The kinds of possible population

 

suppressing effects that can be identified as arthropod in origin
are: eating of entire young seedlings, grazing on leaves, stems or
branch tips of vegetative parts of plants, leaf tying on branch tips,
grazing on flowering or fruiting branches and predation on seed or
interference with the seed population--either while the seeds are
still on the parent plant or after they have been dispersed to the
litter of the forest floor.

Predation on the_y. lineare seedlings occurs and in some years
(Cantlon, pers. comm.) is high. Field observations suggest that

Atlanticus testaceus could be largely responsible for these losses

 

since its nymphs emerge at about the same date as the green cotyledons

of Melampyrum appear above the litter. Data in the present study do

 

not permit accurate assessment of the importance of arthropod preda—
tion on g. lineare seedlings but evidence of feeding on the vigorously
vegetative plant is conspicuous.

Grasshoppers, particularly Atlanticus testaceus, the shield-

 

backed katydid, appear to be the major invertebrate feeder on

56
_g. lineare in northern lower Michigan, and certainly was the most
important insect in the study area in 1965-1966. They were not abun-
dant enough to bring about the collapse of any of the_§. lineare
populations studied, however.

Grazing of potentially seed bearing parts for the most part
takes place before the middle of July (Fig. 3). For this reason June
and first part of July strongly determine the extent of vegetative
feeding that takes place during a summer. No data are available on

the number of seeds eaten by an Atlanticus katydid per day, nor were

 

katydid populations estimated. We do not know in any precise terms
the extent of damage to capsules or just what this type of damage
means to the plant population during the year. However, various notes
were recorded on capsules that were missing or damaged and in some
areas it could be presumed from the high frequency of damaged capsules
that the effect was considerable. Also, from observations in the

laboratory, it was noted that Atlanticus, when placed with a plant

 

overnight, could destroy many capsules and seeds. Seed and capsule
production per plant for treated and untreated plots is shown in

Fig. 12. Note that the number of capsules per plant is higher for the
treated plots in most but not all plot years. The amount of feeding
on branches is shown in Fig. 13. In the untreated plots it makes an
early summer peak being especially prominent in ”HGQ" in 1965. The
difference in grazing damage between the treated and untreated plots
is shown in Fig. 13. The largest differences occur in the same plot
for years in which the largest differences in numbers of capsules per

plant occur. It would not be unlikely that severe grazing suppresses

WW
0

Capsules per plant '
c>

 

I-‘KN
0

Capsules per plant
c> EL;

 

'57

Fig.12-- Treated and untreated plots in relation
to the number of capsules per plant for 100

‘ randomly located plants around the ten by ten meter
perimeter.

Plot "HGQ" 1965

Plot “127" 19b5

 

WW
0 O

...;
O

 

capsules per plant

 

Plot ulalu 1965

.,/’"
./'

 

July Aug. Sept f—

 

 

 

 

p _ .
g I Plot "HGQ" 1966
ii
2
0.50
mi
3350
a. /
g 10 4;, a‘
1:3 ...—3;
g Plot 51273 l9b6
H
0..
F4
2:50
m
.3 50
g .
o. 10 ;, "'
a 1...,”
treated

 

4.) ‘ ‘

5 Plot “131" l96b
H

Q:

3 ,

3 50
.a /. ’o.—”

/’
EilO 5/

 

58

Fig.15-- Difference in numbers of missing
branches between treated and untreated plots
for 100 ramdonly located plants on the ten by
ten meter perimeter. Difference equals damage
in the treated plot minus untreated plot.

I20
' 1965

   
  
 
  
  

100"

 

Plot "HGQ"

t}.

villa- Plot "131..

Plot "127"

Number of branches eaten
a:
O

 

 

 

 

 

59
capsule production or that the same insect eats both capsules and
vegetative parts.

The importance of vegetative feeding during the summer should
not be overestimated. It was frequently observed in the field that
damage to the vegetative structures of the plant were compensated for
by the production of new branches, particularly early in the season.

Mortality of seeds in the litter and in mature capsules un—

doubtedly contribute to population losses in Melampyrum. Field obser-

 

vations indicate that microorganisms kill some seeds and in the
laboratory the frequency of infection is greater where seed coats show

insect damage (Cantlon, pers. comm.). In the laboratory Atlanticus

 

has been observed to eat seeds placed on the floor of the cage. It
seems logical that they may also eat seeds from the forest floor in
their native habitat. This could explain the decline in the number

of grasshoppers found on Melampyrum plants during the later summer

 

after seed dispersal into the litter begins in early August. Also
certain insect larvae such as wire worms have been observed in situa—
tions suggesting they eat some seeds from the litter. The overall

effect of seed aggregating by insects on seed mortality is not known,

but Carabid beetles, which make sizeable seed concentrations in the
forest floor, could influence population numbers through this activity.
Seed germination percentages are lower in these large seed concentrations
(Cantlin and Curtis 1968) and some seed eaters (e.g. the wireworm) were
found mostly in such seed concentrations. It also seems likely that

various mammals and birds eat some seeds from the litter.

60

As suggested above, Melampyrum lineare can withstand a fairly

 

large amount of grazing damage and still produce seeds. Feeding on
leaves and on terminal and branch ends are the most common types of
damage. Leaf feeding is the most common, while branch feeding is the
most destructive. Leaf feeding varies greatly and may range from
just a small piece missing from the leaf to total defoliation. Many
types of leaf feeding can be assigned to particular insects while
others are characteristic of several insects.

Grasshoppers often take the entire leaf, but most other insects
eat only a part of it. Leaf feeding for the purpose of this work was
divided into five classes or degrees of damage (Fig. 19). Class 1
consists of only a small portion of the leaf missing. Class 3 indi—
cates that about half of the leaf was eaten and class 5 indicates
that one or more leaves were eaten in their entirety. Class 1 is by
far the most common while class 5 was the least common (Fig. 19).
Classes 1, 2, and 3 are the result of a large variety of insect feeding,
while Classes 4 and 5 were caused mostly by grasshoppers and certain
Lepidoptera larva. Except in early summer and spring when the plants
are small, leaf damage was normally less than complete defoliation.

Branch and terminal feeding are probably the most important
type of vegetative feeding. Without branches and terminals no seeds
would be produced. Also, the time of the year that branch and ter-
minal feeding takes place is very important.

Branch or terminal feeding results in the loss of the entire
growing end. Subsequent plant growth takes place from axillary buds

at the base of the severed branch. If branch feeding takes place

61
early in the year while the young plant is growing rapidly, recovery
may be quick and nearly complete, with the plant being nearly normal
in shape and branch number. When branch damage takes place toward the
time of seed formation, the result may be a considerable loss of seed
production. Although new branch growths may be initiated, fewer
capsules will have time to mature. It is also interesting to note
that these replacement branches appear more susceptible to grazing,
possibly because they are the most tender part of the plant and are

preferred by Melampyrum grazers.

 

Branch chewing is of two types. In one, the branch is chewed
off near the end, leaving leaves and perhaps secondary branches
farther down the stem. When this occurs, secondary branches usually
take over and replace the old stem. In the second type of feeding,
the branch eaten off is the main stem or only major branch. In such
cases the plant may die or a new branch may be formed from a surviving
axillary bud. This type of recovery was often noted and if the damage
occurred early enough, capsules and seeds would be produced.

Insect feeding upon Melampyrum plants is responsible for only

 

a slight reduction in survival of the local plant population (Fig. 17).
The main effect is on seed mortality and its impact on subsequent
generations (see Figs. 12, 14, 15).

Late in the summer, large and mature Melampyrum plants have

 

been observed cut off about 10 to 15 cm. from the ground and severed
plants left lying on the ground. Although the responsible organisms
were not observed, it is possible that cutworms account for this type

of damage. Mortality of a large plant at this stage results in a loss

62

of many capsules. However, this type of damage was observed only in
isolated spots and probably has little effect on the overall population.

It is interesting to note that mortality in the 100 staked
plants appeared to take place in groups. The poor and smaller plants
would have a tendency to be clumped and the same was true of the
healthy plants. Cantlon_g£ El. (1963) have pointed out that patterns
of mortality may be associated with changes in the roots of host trees

to which Melampyrum plants are attached. From this, plus the fact

 

that the survival rates between treated and untreated plots showed
little difference, I would conclude that in the areas studied factors
other than insect predation, e.g., drought have a greater effect on
plant mortality, at least after the plants are established and growing
well.

It should be kept in mind thatzgy lineare may sustain more in-
sect caused mortality on certain sites than on others. Specifically,

the response of an insect to Melampyrum may be influenced by the

 

character of the latter's host plant, soil moisture and other physical
or biological features of the habitat, and the particular local popu-

lation of the insect at that site. The katydid, Atlanticus testaceus,

 

is a good example of this latter point since it exhibits a close

ecological relationship with Melampyrum lineare in the "HGQ” study

 

area. On the other hand, Atlanticus populations only a short distance

 

away can show completely different feeding habits and behavior traits

when Melampyrum is absent.

 

In the habitats characterized by oak—pine vegetation on sandy

soils in northern Michigan, the understory vegetation is not very rich

63

in species of herbaceous plants, and Melampyrum is often the most

 

common herb. Feeding experiments and field observations both suggest

that Melampyrum lineare is the only plant from this forest that these

 

populations of Atlanticus testaceus will eat. If this is the case,

 

these populations of Atlanticus are in fact dependent upon Melampyrum.

 

 

The factors which influence the population size of_M. lineare
may well vary from place to place over its range as climatic, micro-
climatic, soils, forest history, local biota and other situations
are different. This is substantiated by observed differences in col-

lections of Melampyrum feeding insects made in different parts of the

 

state. Several specimens of various insects were collected on this

plant in areas outside of the study regions which were never collected
in the study areas. Moisture stress on populations also shows regional
differences. Drought and predation may well be the two most important

factors. These could work together to influence Melampyrum populations.

 

Population dynamics, biology, behavior, and ecology of

Atlanticus testaceus must be understood before the populations of

 

Melampyrum lineare in the study areas can be completely understood and

 

related to their environment.

The persistence of branch damage to Melampyrum after the first

 

week in July is due to several things. The first is that the change

in feeding of Atlanticus takes place over a period of time and this

 

katydid undoubtedly continues some branch feeding after beginning to
feed on capsules and seeds. Secondly, branch and terminal feeding by

grasshoppers other than Atlanticus may keep on at a normal rate. If

 

we assume that the feeding of other grasshopper species continues all

64
summer, it is possible that their feeding does not do a great deal

of damage early in the summer and that Atlanticus is responsible for

 

the large amount of feeding at that time. It seems unlikely that non-

Atlanticus grasshoppers could be responsible for major fluctuations

 

in Melampyrum population sizes. Grasshoppers other than Atlanticus

 

 

were not observed to feed on the seeds of the plant. A third pos-
sible cause of the continuing smaller branch loss may be other insects,
particularly Lepidoptera. Fourth, weather, mammals, and birds may
from time to time be responsible for the loss of plant parts.

Fig. 3 shows a marked drop in feeding on branchs in July.
It also shows that after this initial sharp drop in the number of
branches eaten, losses occur at a fairly uniform rate the rest of
the summer. Rate of branch loss becomes less during the summer until
by the last part of August it is essentially nil. I would further
suggest here that by the middle of August, all grasshopper feeding

on Melampyrum branches stops and what little branch loss does take

 

place could well be done by insects other than grasshoppers.

Grasshopper—produced damage to Melampyrum occurs mostly to

 

leaves, terminal ends and later on, to seeds. Other types of damage
have been observed in sites and on plants collected in the field.
Among this miscellaneous damage are chewed stems or stem cutting re—

sulting in bent-over branches. Feeding Melampyrum to caged Atlanticus

 

 

indicates that this damage may be due to varying amounts of stem
tissue removed by the grasshopper.

Night observations of actual feeding by Atlanticus are less

 

numerous than simple records of presence on Melampyrum plants. The

 

65
disturbance created by the observer and the light used to locate them
caused feeding to stop.

The presence and specific location of Atlanticus on Melampyrum

 

 

is shown in Fig. 18 for August of 1966. I observed that 84% of the
katydids are on sections of the plant, such as terminals, stems, and
capsules where they could be eating capsules or seeds. Only 13% were
on leaves and parts not related to capsule feeding and only .04% were
eating flowers.

Some interesting facts about insect predation on M. lineare
are shown in Fig. 20. The sharpest rise in leaf feeding matches up

with branch and terminal feeding during the time that Atlanticus is

 

eating entirely green plant parts. However, leaf feeding does not
drop off nearly as much as branch feeding after the first of July for
what I feel are two major reasons. First, grasshoppers other than

Atlanticus are feeding mostly on leaves and they do not stop feeding

 

on them in mid—summer. Second, many of the other insects which feed

on Melampyrum feed on the leaves. Therefore, leaf feeding continues

 

at a higher rate than branch and terminal feeding throughout the
summer.
In at least one instance (Cantlon oral communication 1966),

predation on a Melampyrum population was great enough to reduce one

 

year's seed output to near zero. Whether the predation was by

Atlanticus or not is unknown. If it was this katydid, no new seeds

 

were available for the latter stages of the insects' life cycle and
its reproduction could suffer, unless it found an adequate alternative

food.

66

 

 

 

 

Fig.14-- Seeds per plant Fig.15-- capsules per_
from harvested plots in plant from harvested plots
the "HGQ" area in 1965. in the "HGQ"area in 1965.
' an

O
O/
l
12 . .5
.. to E201
c - cm
:9. .. .
j 8. l/
o ‘ m
9* " 10 /
3 5H ' - 7% ,"
O) . p, O
a
:3 / \\. ._, ’l
/' _
/ ,- /
:x , I/
0 2 4 i 0 2 4 5
Time in weeks. '.Time in'weeks
' treated

 

— — — untreated

Number of flowers per plant

_ 100 €\
Fig.16-- Number of ‘Et\
.
flowers per plant for \
100 plants in the "HGQ" a so ‘\
plot for August 15,1965- '3 \
m \
‘c’: \-
t: treated g 60 \-
ut= untreated 0‘ \ D
“5' \
3 \
l 4c): ‘0 \
3 o
6 g ,3
g i Q‘ _Fig.l7-- Percent of
g E 20 plants alive for five
1}
i g square meters in the
I 3 g "HGQ" plot, 1965.

 

 

 

 

 

0 2 ( 'uS

Time in weeks

67

Fig.18-- Observed position of
Atlanticus on melampyrum plants
during night observations.

 

 

  
   
  
 
 
   

 

 

 

 

35 T-- Terminal
a S-- Stem
* é?“ U-- Capsule
B B—- Branch
8 F-- Flower
m
5&2“ SE-- Seeds
% I!“ leaf
2 O—- Other
.910 f
a r
:3 '.
z 5
5
i

Fig.19-- Total number of leaves
with eabh degree of damage for
100 plants in the "HGQ" plot for
August 15.'1965.

UT

N
0.
C3

120'

Number of leaves for 100 plants

 

 

 

 

of
T

 

Degree of feeding damage

 

68

Fig.20-— Number of leaves per plant in treated
(9—0) and untreated (o—--o) plots for 100 plants,
"HGQ" 1965.

t
E

100

U!
a

 

 

Number of leaves per plan

N
(J!

 

 

TIME

Fig.21-— Number of flowers per plant in treated
(""0 and untreated (O-—-0) plots for 100 plants, _
"HGQ" 1965. -

fl
6
‘—

 

 

flh: ‘ —
30 5 24 13

22 q 13
June . July me Aug ' Sept

number of flowers per plant
"I

69

In some years, Melampyrum populations have been observed to

 

collapse from drought (Cantlon oral communication 1966). Such a drop

in the plant population during the Atlanticus feeding period un-

 

doubtedly would affect local Atlanticus populations adversely. Since

 

a large Melampyrum seed population carries over in the litter, the

 

plant's fluctuations are moderated (Cantlon, EE_El: 1963, Curtis &

Cantlon 1966).

CONCLUSION

In light of the fact that Atlanticus appears to be the major

 

insect influence on Melampyrum population much attention is directed

 

at this relationship.
In a forest such as is found in the ”HGQ" area but in which

_M. lineare is absent, it is possible that Atlanticus would have no

 

stable food plant and that large populations of this insect could not

be supported. Since no abundance surveys of Atlanticus have been

 

made, the hypothesis has not been tested. One could speculate that
where these two populations co—exist they exhibit some dynamic balance
between them.

It is possible that under low Melampyrum population levels

 

predation by Atlanticus could keep the plant from increasing. It

would appear that some factor needs to give Melampyrum a chance to

 

obtain a headstart on the katydid. An unusually high germination
percentage of litter—stored seed is one possibility. Another is a

severe drop in the Atlanticus population. After obtaining a lead,

 

Melampyrum is probably able to keep ahead of Atlanticus for a year

 

 

or so until Atlanticus populations catch up again. Other factors

 

such as the frequent droughts in the region help to bring about a
decrease in the plant population and this in turn could be reflected

in a reduced Atlanticus population. The two to three year seed

 

carry-over from a Melampyrum "high” would tend to dampen violent

 

oscillations in this predator-prey relationship.

70

71

The extremely close relationship that is found between Atlanticus

 

testaceus and M. lineare is very interesting when we consider the pre—
vious studies (Gangwere 1966). These suggest that, within an area of
only two or three square miles, or even smaller, there may be found

two populations of Atlanticus acting in a completely different manner.

 

In our case it is possible that the species could be represented by
two groups: one, the old field, ecotone variant and the other, the
woodland variant with which this study is involved.

From an ecological point of view the two populations are dif-
ferent in many behavioral and biological characters. The two probably
have quite different population dynamics. The old field populations
probably have a much larger variety of food and perhaps a more re—
stricted habitat area, while the woodland unit has a more restricted
diet and is more limited by food than habitat. It would be most in—
teresting to explore whether these two populations are genetically
different or simply local nongenetic adjustments of a wide-ranging
katydid to different available foods. Since Melampyrum is about the
first herb available in spring to the emerging nymphs, they may become
"imprinted” toward it and since it remains available they retain
their narrow range of food preference. .5. testaceus thus may serve as
a regulatory factor ongM. lineare populations in the natural system in
which this experiment was conducted. Population densities of

Melampyrum are directly dependent to various degrees on the amount of

 

predation, and the amount of predation is directly related to the

number of seeds and capsules produced by Melampyrum lineare. Melampyrum

 

 

can only build up to large numbers under favorable conditions, probably

72

including low predation by Atlanticus. In areas treated to control

 

insects, populations of Melampyrum tend to increase relative to un—

 

treated areas.
Plant populations show a response to the predatory activities

of Atlanticus and are reflected in the reduced number of Melampyrum

 

 

capsules (Fig. 12) and in long term fluctuations of the Melampyrum

 

population. The greater the amount of predation between treated and
untreated plots the greater is the difference in the number of capsules
per plant between treated and untreated plots (Figs. 12, 13). It seems
reasonable that in areas of low differences in branch damage between

treated and untreated plots Melampyrum population fluctuations are

 

slower, taking a longer period of time to show differences than is the

case under very heavy predation by Atlanticus.

 

Other insect—Melampyrum relationships are of significant propor-

 

tions only in isolated situations. Ecological conditions favorable to
a particular insect may, in a given area, allow an insect to influence

Melampyrum populations, but these situations are of short duration and

 

the effects are only felt among a few plants. Also, seed carry-over
cancels out these small influences.

While Atlanticus may be the only insect species inflicting

 

significant damage to a wide ranging Melampyrum population, the combined

 

influence of non-orthoptera insects should not be overlooked.
Two insects which are not really understood in relation to the

dynamic Melampyrum population are the carabids and the formicids.

 

The influence of seed batching by carabid's needs more study in rela—

tion to its influence to the plant population. The formicid problem

73
is interesting and perhaps more complex than first appeared. These

ants may be either beneficial or harmful to the Melampyrum population.

 

SUMMARY

Their remains no doubt that insect herbivores have an effect

upon the Melampyrum population in the areas where this study took

 

place. The influence of insects varies from location to location, but

Atlanticus appears to be the major insect influence over the plant

 

population. It eats vegetative plant parts early in the season and
later switches to eating capsules and seeds. The influence of insects

other than Atlanticus is viewed in this study as a combined influence

 

but separate from the over all Melampyrum population. Certain pre—
cautions must be placed on insect influences because of a lack of
understanding of carabid influence, formicid behavior, and seed litter
destruction.

Areas of Melampyrum populations when treated with an insecti-

 

cide show positive response and populations increase in size due to

the lack of insect predation.

74

 

LITERATURE CITED

Arnett, Ross H. 1963. The beetles of the United States. The
Catholic University of America Press, Washington, D.C.

DeBach, Paul. 1964. Biological Control of Insect Pest and Weeds.
Reinhold Publishing Corporation, New York.

Cantlon, J. E., Curtis, E. J. C., and Malcolm. 1963. Studies of
Melampyrum lineare. Ecology 44:466—474.

 

Curtis, E. J. C., Cantlon, J. E. 1963. Germination of Melampyrum
linearezInterrelated effects Afterripening and Gibberellic Acid.
Science 140:406-408.

 

1965. Studies of the Germination Process in Melampyrum
lineare. Amer. Jour. Bot. 52(6):552-555.

 

1966. Cell wall of Melampyrum lineare SeedzCarbohydate
Components. Science 151(3710):580-581.

 

1968. Seed Dormancy and Germination in Melampyrum lineare.
Amer. J. Bot. 55(1):26-32.

 

Dillion, E. S. and Dillion, L. S. 1961. A Manual of Common Beetles
of Eastern North America. Row, Peterson and Company.
Elmsford, New York.

Forbes, W. T. M. 1948. Lepidoptera of New York and Neighboring
States. Cornell University Experiment Station. Memoir 274,
Part II, Geometridae, Sphingidae, Notodontidae, Lymantriddae.

. 1954. Lepidoptera of New York and Neighboring States.
Cornell University Experiment Station. Memoir 329. Part III,
Nbctuidae.

1960. Lepidoptera of New York and Neighboring States.
Cornell University Agricultural Experiment Station. Memoir
371. Part IV, Agaristidae through Nymphalidae Including
Butterflies.

Gangwere, S. K. 1966. The Behavior of Atlanticus Testeaceus
(Orthoptera: Tettigoniidae) on the E. S. George Reserve,
Michigan. The Michigan Entomologist. V61. 1, No. 3.
pg. 95-100.

75

76

1967. The Feeding Behavior of Atlanticus testaceus
(Orthoptera:Tettigoniidae). Annals of the Entomological
Society of America. V61. 60, No. 1. pg. 74—81.

 

Huffaker, C. B. 1959. Biological Control of weeds with insects.
Annual Review of Entomology, V61. 4.

Huffaker, C. B. and Kennett, C. E. 1959. A Ten-Year Study of
Vegetational Changes Associated with Biological Control of
Klamath Weed. J. of Range Management 12(2):69-82.

Slobodkin, L. B. 1964. Growth and Regulation of Animal Populations.
Holt, Rinehart and Winston. New York.

APPENDIX I

INSECTS OF MELAMPYRUM LINEARE DESR.

 

 

 

 

 

 

 

 

 

 

 

 

ORTHOPTERA
Tettigoniidae
Atlanticus testaceus (Scudder)
Acrididae
Melanoplus bivittatus Say
Melangplus fasciatus F. Walker
Pseudopomala brachyptera (Scudder)
Chloealtis conspersa Harris
Spharogemon bolli bolli Scudder
COLEOPTERA
Carabidae
Synuchus impunctatus (Say)
Calathus sp.
Bruchidae
Acanthoscelides sp.
Curculionidae
Panscopus maculosus Blatch
Conotrachelus posticalus Boh.
Acalyptus curpins (Herbst)
Lathridiidae
Derodontidae

77

78
Chrysomelidae
Dibolia boralis Chevrolat

Disonycha sp.

Microrhopala xerene (Newn.)

 

Coccinellidae

Hyperaspis sp.

 

Alleculidae
Isomira sp.
Elateridae

Limonius basillaris (Say)

 

Seed eating larva in the litter
Scarbaeidae
Serica sp.

Phyllophaga sp.

 

LEPIDOPTERA
Tortricidae
Spareanothis reticulatana Clemens

Archips rosaceana Harris

 

Archips arngospila walker

 

Geometridae
Abbottana clemataria Smith and Abbot
Anacamptodes humaria Guenee
Xanthotype urticaria Swett

Several unknown Geometridae larva

79
Noctuidae
Papaipema sp.
Autographa epigaea Grote
Noctuidae larva inside capsules
HYMENOPTERA
Tenthredinidae
Formicidae
Tapinoma sessile (Say)
Myrmica sp.
Camponotus noveboraceusis (Fitch)
Crematogaster lineloata (Say)
Formica pallidefulva Latreille
Camponotus nearcticus Emery
Apidae
Bombus sp.
NEUROPTERA
Chrysopidae
Chrysopa sp.
THYSANOPTERA
HOMOPTERA
Aphididae
Macrosiphum solanifolii (Ashmead)
Scale
HEMIPTERA
Pentatomidae

Euschistus sp.

 

80
Corimelaenidae

Corimelaena sp.

 

DIPTERA
Melichiidae

Unknown Diptera leaf miner

Non-insect arthropods

ARACHNIDA
Araneae
Salticidae
Thomisidae
MYRIAPODA

Diplopoda

APPENDIX II

FEEDING HABITS OF MELAMPYRUM INSECTS

Synuchus impuntatous . . . . . . . . . . S, P

 

calathus O O O O O O O O O O O O O O O O S, P

Acanthoscelides . . . . . . . . . . . . F

 

Pansocopus maculosus . . . . . . . . . . L

 

Dibolia boralis . . . . . . . . . . . . L, BU, F

 

Disonycna . . . . . . . . . . . . . . . L

Microrhopala xerere . . . . . . . . . . L

 

Limonius basillaris . . . . . . . . . . F

 

serica O O O O 0 O O O l O O D O O O O O L

Phyllophaga . . . . . . . . . . . . . . L

 

Spareanothis reticulatana . . . . . . . L, TE, BE

 

Abbottana clemateria . . . . . . . . . . L, TE, BE

 

Anacamptodes humaria . . . . . . . . . . L

 

Papaipema . . . . . . . . . . . . . . . L

Autographa epigaea . . . . . . . . . . . L, TE, BE

 

Diprionidae . . . . . . . . . . . . . . L
Chrysopa . . . . . . . . . . . . . . . . P
Aphididae . . . . . . . . . . . . . . . S, B
Scale . . . . . . . . . . . . . . . . . ST

EUSChistus O O O O O O O O O O O O O O O C, S, B

 

Corimelaena . . . . . . . . . . . . . . C, S, B

 

81

Atlanticus testaceus .

 

Acrididae
Diptera
Spiders

Millipeds

O

82
L, TE, BE, c, F, 3, ST, B, P
.......L,TE,BE,C
......P

S

FEEDING HABITS OF MELAMPYRUM INSECTS

TE .

BE

ST .

BU

 

LEGEND

leaves

terminals of plant

branch ends

stem

branch

capsules

seeds

flowers

Predatous on other arthropods

buds

HICHIGQN STQTE UNIV. LIBRR

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