THE TESTlNG OF POSSIBLE ALTERNATE HOSTS 0F
ANAPHES FLAVIPES FOERSTER (HYMENOPTERA: MYMARIDAE)
AN EGG PARASBTE OF THE CEREAL LEAF BEETLE,
OULEMA MELMOPA L (COLEO PTER-A: CHRYSOMELIDAE)

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ABSTRACT

THE TESTING OF POSSIBLE ALTERNATE HOSTS OF ANAPHES FLAVIPES
FOERSTER (HYMENOPTERAjMYMARIDAE) AN EGG PARASITE OF THE CEREAL
LEAF BEETLE, OULEMA.MELANOPA L. (COLEOPTERA:CHRYSOMELIDAE)

 

 

by Anastasia Thanassoulopoulos

The use of "unnatural" hosts for the laboratory propagation of
biological control agents such as parasites and predators has been re—
viewed.

Anaphes flavipes, an imported egg parasite of the cereal leaf

 

beetle (Oulema melanopa), was tested to determine if it would attack

 

beneficial insects in its new home, and to determine if the eggs of
native insects would be suitable alternate hosts for the survival of
the parasite.

The eggs of several species were tested, and emphasis was
placed on finding eggs of species belonging to the same family as the
cereal leaf beetle or of related species. The results showed that
none of the tested eggs were suitable for the parasite. In the case
where the parasite apparently oviposited in the eggs of the Colorado

potato beetle, Leptinotarsa decemlineata (Say), and one of the several

 

"species"(?) of the three-lined potato beetle, Lema trilineata (Olivier),

 

no development of progeny occurred.
The tests were not extensive enough to conclude that_§. flavipes

is a parasite restricted to cereal leaf beetle eggs.

Anastasia Thanassoulopoulos
The acceptability and potential use of biological control agents

obtained from species other than the target species is reviewed.

THE TESTING OF POSSIBLE ALTERNATE HOSTS OF ANAPHES FLAVIPES

 

FOERSTER (HYMENOPTERAfMYMARIDAE) AN EGG PARASITE OF THE CEREAL

LEAF BEETLE, OULEMA.MELANOPA L. (COLEOPTERA:CHRYSOMELIDAE)

 

BY

Anastasia Thanassoulopoulos

A THESIS

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

MASTER OF SCIENCE

Department of Entomology

1967

ACKNOWLEDGMENT

The author would like to express her thanks to Dr. F. W. Stehr,
for his guidance and help during the course of this work and in the
preparation of the manuscript.

The author would also like to thank the other members of her
committee, Drs. G. E. Guyer, J. E. Bath, and J. L. Lockwood, for
their assistance during her studies.

Thanks are due to Mr. L. Barton for providing the continuous

supply of parasites necessary for this work to be completed.

ii

TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . ... . . . . . . ii
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . v
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . vi

PART I. THE ACCEPTABILITY AND USEFULNESS OF UNNATURAL HOSTS
IN PARASITE AND PREDATOR REARING PROGRAMS . . . . . . . 1

Discussion . . . . . . . . . . . . . .s. . . . . . . . 6

PART II. THE TESTING OF POSSIBLE ALTERNATE HOSTS OF .
ANAPHES FLAVIPES . . . . . . . . . . . . . . . . . . . 8

 

Introduction . . . . . . . . . . . . . . . . . . . . . 8
Materials and Methods . . . . . . . . . . . . . . . . . 10

Tests of Anaphes on the oviposition of the

OLE eggs grouped on end in clusters . . . . . . 14
Results . . . . . . . . . . . . . . . . . . . . . . . . 15
Discussion . . . . . . . . . . . . . . . . . . . . . . 21

PART III. THE ACCEPTABILITY AND POTENTIAL USE OF BIOLOGICAL
CONTROL AGENTS OBTAINED FROM SPECIES OTHER THAN
THE TARGET SPECIES . . . . . . . . . . . . . . . . . 25

IntrodUction . . . . . . . . . . . . . . . . . . . . . 25

Use of parasites and predators . . . . . . . . . . . . 26
Use of microorganisms . . . . . . . . . . . . . . . . . 30
The use of viruses . . . . . . . . . . . . . . . 31
The use of rickettsiae . . . . . . . . . . . . . 32
The use of bacteria . . . . . . . . . . . . . T 32
The use of nematodes . . . . . . . . . . . . . . 33

iii

The use of protozoa
The use of fungi .
Discussion . . . . . .

LITERATURE CITED .

iv

Page
34
35
36

4O

LIST OF TABLES

Table Page

1. Tests of eggs as possible alternate hosts of the
cereal leaf beetle egg parasite Anaphes flavipes. . . . 23

 

LIST OF FIGURES

Figure Page

1. Females of_A. flavipes on cereal leaf beetle egg .V. . . 11

vi

PART I

THE ACCEPTABILITY AND USEFULNESS OF UNNATURAL HOSTS IN

PARASITE AND PREDATOR REARING PROGRAMS

Entomophagous insects are classified on the basis of certain
functional relationships with their hosts into three categories:
1. Parasites——the immature stages develop at the expense of a single
individual which is termed the host. The host does not necessarily
belong in the same taxonomic class with the parasite. Examples are
the various lice and ticks that attack mammals. 2. Parasitoids--they
differ from true parasites in that the development of an individual
destroys its host; the host is usually of the same taxonomic class.
In comparison with their hosts, parasitoids are of relatively large
size, and they are parasitic as larvae only, the adults being free-

living forms. Anaphes flavipes Foerster is a parasitoid of the cereal

 

leaf beetle Oulema melanopa L. 3. Predators--in which the larvae con-

 

sume more than one individual prey to reach the adult stage. There is
no clear-cut line of demarkation between parasites and predators. The
larvae of some Hymenoptera develop in a host egg mass and might be
called egg predators. There are some coccinellids which are able to
develop in one large coccid individual, and in this case would tend to
meet the definition of a parasite (Doutt, in_DeBach 1964). For these
reasons the term host will be used instead of prey for predators as

well as for parasites.

2

In nature under field conditions parasites and predators usually
attack a host, the progeny are fertile, and this suitable host is
described as a natural host. Parasites and predators in the laboratory
will sometimes attack hosts on which they never develop in the field,
but which will serve a very useful purpose for mass rearing.

The use of these "unnatural” hosts has proven to be a most effec—
tive means for the production of biological control agents when the
provision of natural hosts in sufficient quantity is difficult or im-
possible. Some of the natural hosts have a single generation per year
which makes them poor species for mass-rearing programs; others have
different habits such as living in the larval stage in parts of growing
plants which are difficult to handle to produce mass infestations.

Some natural hosts become very susceptible to epidemics of diseases
when kept in large numbers and the mortality is heavy. Because of
these factors the propagation of large numbers of natural hosts in the
laboratory may be very expensive (Simmonds 1944).

Salt (1938) pointed out the characteristics of a suitable or.
unsuitable host: 1. Physical characteristics, such as the permeability
of the egg shell, the hardness of the shell, the rigidity of the shell,
the fluidity of the contents, and the quality of the contents. 2.
Chemical characteristics, which might affect the parasite within it in
2 ways, as environment and as a food (nutritional adequacy).

The possibilities for a parasite to develop on its unnatural
host were summarized by Simmonds (1944). First, the unnatural host is
attacked by the parasite and the subsequent development is normal.

Examples are the mass breeding of Trichogramma evanescens westw. on

 

Sitotroga cerealella Oliv. eggs and the breeding of Chelonus texanus

 

 

3

Cress. on Anagasta kfihniella Zell. eggs (Simmonds, 1944). Trichqgramma

 

 

was reared for liberation against Diatraea saccharalis F., Carpocapsa

 

 

pomonella L., and Grapholitha molesta Busck. (Flanders, 1929, Schread

 

and Garman, 1933). Chelonus was reared for use against the beet web-

worm Loxostege sticticalis L. (Simmonds, 1944).

 

Second, the unnatural host is attacked by the parasite and sub-
sequent development is subnormal, so a_heavy mortality occurs to the

progeny. Salt (1938) found that by using eggs of Bruchus obtectus Say

 

for Trichogramma only 1.5% of the attacked eggs produced parasites.

 

Third, the unnatural host is not attacked but the parasite's
eggs are transferred to it manually. In this situation three things
might occur; the parasite development is normal, subnormal or no devel-
opment of the progeny occurs.

A large number of examples through the literature illustrate
the usefulness and the importance of mass~rearing on unnatural hosts
in a biological control program, and the success with which the methods
have been used. In the mass production of Chrysopa californica Coq.,
Finney (1948, 1950) used both fresh eggs and the mature larvae of the

potato tuber moth, Gnorimoschema operculella (Zell.), as a host.

 

Flanders (1929, 1930) reported the mass rearing of Trichogramma

 

minutum (Riley) on the eggs of the Angoumois grain moth, Sitotroga

cerealella Oliv. for the control of the codling moth, Carpocapsa

 

 

pomonella L., the oriental fruit moth, Grapholitha molesta Busck., and

 

the sugarcane borer, Diatraea saccharalis F.

 

Bradley (1941) utilized the eggs of the Mediterranean flour moth,

Anaggsta kfihniella Zell., for the mass propagation of Chelonus annulipes

 

 

Wesm., a larval parasite of the European corn borer, Ostrinia nubilalis

 

4
Hb. The same host was used by Simmonds (1944) for raising a large,

number of Chelonus texanus Cress, an egg parasite of the beet webworm,

 

Loxostege sticticalis L.

 

In the laboratory propagation of Macrocentrus ancylivorous

 

Rohw., a parasite of the oriental fruit moth, Grapholitha molesta, the

 

parasites were reared on the larvae of the potato tuber moth,

Gnorimoschema operculella (Finney, Flanders and Smith 1947). They

 

demonstrated that the unnatural host is more amenable to insectary
techniques than the larvae of the strawberry leaf roller, Ancylis

comptana fragariae (walsh and Riley), the natural host.

 

Simmonds (1944) reared Spalangia drosophilae Ashm., a parasite

 

of the frit fly, Oscinella frit (L.) using as hosts the puparia of

 

Drosophila melanogaster Mg. Although this is apparently a good example

 

of the use of an unnatural host, Simmonds stated that "it is difficult

to be sure that Drosophila is not a natural rather than an unnatural

 

host".
Doutt and Finney (1947) reared economically, and in quantity,

Dibrachys cavus (walker) using as the "unnatural" host mature larvae

 

of the potato tuber moth,_§. operculella which had been killed in hot

 

water and coated with paraffin wax. Mnesebeck (1953) had reported

about 93 hosts attacked by Dibrachys cavus (walker) including

 

E, operculella, but in the above experiments the conditions of the

 

host were entirely "unnatural" since they were killed and coated with
wax.
Finney (1953) successfully propagated Stethorus vagans

Blackburn, a predatory beetle attacking the two-spotted mite,

5

Tetranychus bimaculatus Harvey, by using a colony of the six-spotted

 

mite, Tetranychus sexmaculatus Riley.

 

The control of the red scale Aonidiella aurantii Mask., in

 

California by Flanders (1951), gives another example of the usefulness
of unnatural hosts in mass-rearing programs. The economic and effi-

cient production of the Chinese golden chalcid, Aphytis chrysomphali

 

(Mercet) was accomplished by using the ivy scale (= oleander scale)

Aspidiotus hederae (vallot).

 

DeBach and Fisher (1956) and DeBach and White (1960) utilised

a pink variety of banana squash (Cucurbita maxima) as the host plant

 

and the uniparental strain of the oleander scale, A, hederae (vallot)

as the host insect for the mass production of Aphytis lingnanensis

 

Comp. This insect is used in the control of the California red.sca1e,

Aonidiella aurantii. They also found that the San José scale,

 

Aspidiotus perniciosus Comst. was a suitable host for the mass propa-

 

 

gation of_A. lingnanensis.
Noble and Hunt (1937) in order to release imported parasites

for the pink bollworm Pectinophora_gossypie11a Saund., bred Chelonus

 

 

 

 

blackburni Cam. on Anagasta kfihniella. The parasite oviposits in the

 

egg of its host (P._gossypiella) but completes its development in the
larval stage.

Schread and Garman (1933) pointed out that the eggs of 11 or
more hosts have been used to breed various strains or species of

Trichogramma. Some of these hosts such as the flour, meal and fig

 

moths, Anagasta spp., and the meal moth, Pyralis farinalis (L.),

 

 

have been studied or used experimentally. The disadvantage of these

hosts is the destructive habit of the young larvae of eating the

6
unhatched eggs after hatching. The same authors suggest that the most

used host is the Angoumois grain moth, Sitotroga cerealella Oliv., be-

 

 

cause it lays large eggs that are preferred by Trichogramma.

 

Discussion

 

It is apparent from the examples mentioned above that the rearing
of parasites on unnatural hosts is of great importance and usefulness
in biological control work.

One question is often raised in relation to the roaring of
parasites on non-natural hosts. Are the parasites capable of attacking
their natural hosts in the field, or will they lose this capacity to
some degree and possibly only attack their unnatural hosts when re-
leased? The same objection is raised in the case of rearing phytopha-
gous insects. Hall (1943) found a distinct biological race of the .

apple maggot, Rhagoletis pomonella Walsh., which shows a restricted

 

preference to dogwood fruits (Cornus amomum Mill.), and which does not

 

interbreed with the race from apple and hawthorn, nor accepts these
fruits as hosts. A very interesting example of the same nature is that
given by Hopkins (1917). He found that the mountain pine beetle,

Dentroctonus ponderosae Hopk., attacks ponderosa pine, lodgepole pine

 

and the sugar pine, but if it develops in one host species it does not
attack trees of any other species, but shows a decided preference for
the species in which it developed. Larson (1927) after 5 years of
study reported that the host-selection principle as outlined by Hopkins

does not appear to hold with the cOWpea weevil, Callobruchus quadri-

 

maculatus Fab. This insect, which normally breeds in cowpeas, will
breed in many varieties of leguminous seeds, no matter which species

of seed they developed in as larvae.

7
In respect to entomophagous insects Thorpe and JOnes (1937)

reared the ichneumonid parasite Nemeritis canescens Grav. on Anagasta

 

kfihniella Zell., on_A. elutella (Hb.) and on the lesser wax moth,

Achroa grisella (F.). They found that parasites produced from Achroa

 

did not change their preference for Anagasta eggs.

In the course of breeding the parasite, Dibrachys cavus Wlk.,

 

 

on both larvae and pupae of Carpocapsa pomonella L., Simmonds (1944)
found that the parasite had a definite preference for the larva, and
after rearing several generations on pupae this strain's preference
for larvae did not change.

It is apparent that it is sometimes possible to change the host
preference of a parasite by forcing it to oviposit on another host.
In this instance a heavy mortality occurs, but as Simmonds (1944) in-
dicated, in this way strains should be selected out of the population
which show adaptability for the new host, and then this adaptability
can be accentuated by continued selective mating. When they do not
adapt to a new host a very heavy initial mortality occurs and the sub—
sequent development of the remaining individuals is often abnormal.
When parasites reared in the laboratory on unnatural hosts are-released
in field, they may attack the new host (Simmonds,l944). An example

of this cited by Simmonds (1944) was the release of Chelonus texanus,

 

reared on eggs of Anagasta, in South Africa for the control of the

beet webworm, Loxostege sticticalis L. The parasite was obtained from

 

Loxostege eggs from Montana.

PART II

THE TESTING OF POSSIBLE ALTERNATE HOSTS OF ANAPHES FLAVIPES

 

FOERSTER (HYMENOPTERAJMYMARIDAE), AN EGG PARASITE OF THE

CEREAL LEAF BEETLE, OULEMA.MELANOPA L. (COLEOPTERA:CHRYSOMELIDAE)

 

Introduction

 

The cereal leaf beetle, Oulema melanopa L., (hereafter called

 

"CLB”) a serious pest of grain crops such as oats, barley, and wheat
was unrecognised as a pest in the United States until 1962 when it was
first identified from Indiana and Michigan. It was probably intro—
duced from Europe where it is widespread, covering most of the Pale—
arctic region from Siberia, westward to the Scandinavian countries,
Central Europe, Great Britain and the Mediterranean countries (Wilson,
1964).

This new pest has received much attention in the United States,
and an intensive effort has produced a large body of knowledge about
the biology, ecology and control of the insect. Chemical control pro-
grams have been developed and resistant varieties have shown promise
(Wilson,l965; Schillinger,1966). Another promising possibility for
control is the introduction and propagation of natural enemies, in-
cluding parasites, predators, and pathogenic microorganisms.

Since the pest became established in the United States, no
parasites have been recovered from it although very little effort has
been spent in looking for natural parasites. Some common predators

8

9
such as coccinellids, a pentatomid, an unidentified scarab, and a mite

are reported (Ruppel, 1964). The lady beetle Coleomegilla maculata

 

lgngi_Timberlake, appeared to be an egg predator of cereal leaf beetles
(Yun and Ruppel, 1964).

The advantages of biological control work are its permanence,
safety, and low cost. The objective in the CLB biological control work
is to select and successfully introduce biological agents from any
place in the world that may help to control the CLB. Hopefully, these
agents will reduce CLB population to a low enough level where insecti-
cidal control will not be necessary.

In Europe several predators have been recovered from CLB. Among

these are Nabis ferus L., Chrysopa‘gp,, Thea s23, an unidentified

 

staphylinid (Ruppel, 1964). The parasites Anaphes flavipes Foerster,

 

Tersilochus carinifer, Tersilochus £23, Tetrastichus julis, and

 

 

 

Lemophagus curtus Townes, have also been recovered.
The objective in this research project was to search for pos-

sible alternate hosts of Anaphes flavipes, an egg parasite of CLB,

 

imported from France and Yugoslavia. The specific objectives were to
determine 1) if Anaphes would attack the eggs of beneficial insects
such as coccinellids and 2) if the eggs of native insects would be
suitable alternate hosts if one were necessary for Anaphes survival.
Emphasis was placed on testing eggs from species of the same
family as the CLB (Chrysomelidae). The use of alternate hosts that
can be continously reared should help very much in the propagation of
the parasites, especially at times when the natural host is not avail-
able in large numbers, and/or when rearing on the natural host would

prove to be more expensive. Cereal leaf beetles are difficult to rear

10
for various reasons, not the least of which is their aestival diapause
which must be broken by storage at cold temperature for 12 weeks.

Salt (1938) pointed out 3 distinct and consecutive phases in—
volved in the parasite's selection of host: 1) Host finding or
ecological selection-~a parasite initially and fundamentally seeks to
locate the host's habitat. Laing (1937) distinguished that the first
step of an insect is to find the host's habitat and then by random and
non-random movements to approach the host itself. 2) Host selection--
each parasite has among the large number of species available, a cer-
tain number which it will attack. The process of the inclusion in
this number or the exclusion from it of some species is known as host
selection (Salt, 1934). 3) Host suitability or physiological selection
—-a suitable host is defined as one on which the parasite can produce
fertile offspring.

In the testing described below, Anaphes were closely confined
with the test eggs, so there was no problem of host location. The
other two phases, host selection (acceptance) and host suitability,

were being tested here.

Materials and Methods

 

The parasite, Anaphes flavipes, (Fig. 1) used in this work

 

originated in Nanterre, France and was obtained from Robert Anderson,
Department of Entomology, Purdue University.

The parasite is sexually dimorphic; the males are easily recog-
nised by their long, slender antennae, and females by the terminal
antennal knob. Both males and females may emerge from a single para-

sitized Oulema egg, and mating takes place within an hour after

ll

“'3 *" as;

 

 

Fig. l.--Females of A, flavipes on a cereal leaf beetle egg
(80X, natural size).

12
emergence. Eggs parasitized by virgin females consistently result in
male progeny, whereas both male and female parasites emerge from eggs
parasitized by mated females. Adult females are active from the moment
of emergence and start laying eggs. The total days required for emer—
gence of the parasite from parasitized eggs varies from 8-11, depending
on the temperature. Adults may live 4-5 days under laboratory condi-
tions. It is not known where the parasites overwinter under natural
conditions.

Eggs of the cereal leaf beetle, Oulema melanopa (L.), were used

 

for rearing a stock culture of parasites and for viability controls

of Anaphes used in testing. The CLB eggs were removed from barley
plants and placed on glass slides which were placed in plastic petri
dishes. When the CLB eggs are fresh, they are covered by a sticky
material in which Anaphes may be come stuck. Therefore, the eggs were
air-dried under room conditions for about 12 hours to reduce the
stickiness before the parasites were placed on them for oviposition.

After the eggs were parasitised, moisture was provided by
adding sterilized water to the filter paper. The dishes were sealed
and placed at room conditions (70-80 F) until the adults emerged.
Moisture was added every few days to maintain the relative humidity
near 100%. The eggs to be tested were field-collected or obtained
from laboratory-caged insects.

The adults of Coccinellidae were first kept in cages containing
different potted plants as pepper, young potatoes, barley, wheat and
different weeds. Aphids collected on alfalfa or on weeds served as
food for the coccinellids. No eggs laying was observed on these

plants but a few eggs were laid on the cage screen or on the wooden

-13
material of the cages. For that reason another technique was tried.
Adult coccinellids were kept in petri dishes and provided daily with
live aphids, or a 10% sucrose solution on a wet piece of cotton; in.
some cases both aphids and sugar solution were offered. The petri
dish bottoms were covered with wet filter paper and a wet piece of
cotton was provided for more moisture. In every petri dish a fresh
ileaf or small twigs were provided as oviposition sites. The best
oviposition was obtained by using the sugar-solution method. One
beetle was placed in each petri dish because if there were more, they
ate the eggs of each other.

Asparagus beetle (Crioceris asparagi.(L.» eggs were collected

 

in the field.-

Adult Colorado potato beetles (Leptinotarsa decemdineata (Say))

 

were placed on potato plants in pots, in cages in a growth chamber.
The-eggs were laid on the potato leaves.

Beetles of Trihabda 22, were collected from golden rod (Solidago)
in the field. Also, various weed plants without eggs were collected
and placed in pots in cages in the greenhouse. All plants were checked
frequently, so the eggs obtained were fresh and 12-24 hours old.

Eggs of different species of insects and mites or spiders found
in the field on different cultivated plants or weeds were also tested.

Gelatin capsules and small vials were used for testing the
eggs. TWO or three female parasites were placed with about 10 eggs.
Eggs and parasites were observed under a binocular microscope until
it was.clear that the parasites did or did not show any interest in
the eggs. The parasites:were then removed and exposed to control CLB

eggs where their behavior was again observed.

14
Both test eggs and control CLB eggs were placed in petri dishes
and held until emergence occurred or until it should have occurred if
the eggs had been successfully parasitized and development was possi-
ble. In all tests the parasites developed and emerged normally from
the control CLB eggs.

Test of Anaphes on the oviposition of the CLB eggs grouped on end in

 

 

cluster. Fresh CLB eggs (24 to 48 hours old) were placed side by side
on end to simulate the conformation of egg clusters of insects such as
the Colorado potato beetle, some coccinellids and the Moxican bean
beetle. Clusters of eggs ranging from 15 to 100 were placed on a
slide, exposed to females Anaphes, and their behavior was observed.

In all replications the parasites preferred to sting only those eggs
which had the sides exposed on the edge of the egg cluster or whose
sides were exposed because the eggs were somewhat slanted within the
clusters. If the sides of the eggs were exposed in some way they did
not sting the ends of the eggs exposed in the center of the cluster.

In a second test clusters of eggs were placed in a plastic
cavity so that only the ends were exposed. In this~case the parasites
stung the ends of the eggs in the cluster by standing on one egg and
placing their antennae on the end of a neighboring egg.

Another test was done in which only the ends of single eggs
were exposed. This test was done to determine if Anaphes will para-
sitize eggs which are inserted in plant tissue with only the end ex—
posed similar to the way the tarnished plant bug lays its eggs. In
this case the parasites approached the eggs several times but did not

sting them, probably because their antennae could not touch the eggs.

15
When the same eggs were fully exposed parasitization was quickly accomr
plished.

CLB eggs when fresh are coVered by a layer of sticky material
which makes it difficult for the parasite to walk over the eggs and
examine them before parasitizing them. .This material in the laboratory
work supports the development of mold and sometimes appears to prevent
the successful emergence of the parasites from the eggs. Therefore,
the eggs were dipped in 1% bleach solution (5.25% NaClO) for 20-30
minutes after they were removed from the leaves to remove the adhesive
material. After that they were rinsed several times in distilled water
to remove the remaining bleach, and then placed in the above described
clusters. Only one egg in one cluster and two eggs in another one were
stung. No eggs were stung in the remaining five clusters that were
tested. This indicates that the adhesive material may attract the
parasites (assuming that the bleach treatment did not adversely affect

the attractiveness or suitability of the eggs in some other way).

Results
The results for each species tested are presented in Table.l.
A short description of each trial follows:

1. Unknown eggs. Ten eggs were found on the ground in Bear lake bog.

 

The eggs were in a mass and resembled coccinellid eggs in color
and shape. They were placed in a gelatin capsule with 2 female
parasites, which did not show any interest in them. Four of the
-unknown eggs hatched, while the rest dried out in the petri dish.

2. unknown eggs. Six eggs were found on pine needles and were tested

 

with 3 female parasites which did not approach them. These eggs

3.

5.

a.

16
were reddish-brown to pink with two light yellow bands on each
side. The eggs were a little larger than CLB eggs and were placed
in pairs on each pine needle. Four of the eggs hatched.
unknown eggs. A.mass of them were found on wild mustard leaves.
The eggs were covered by a thick silk covering on both sides.
The parasites did not show any interest in the unknown eggs, which
did not hatch.

Spider eggs. Twelve eggs, laid in a mass and covered by a silken

 

material were found on weed leaves. The parasite did not approach
the eggs at all.

Mite eggs. Eggs belonging to the genus Glycyphagus-(Glycyphagidae)

were found in a petri plate containing CLB eggs. The CLB eggs

~were covered by.hyphae of fungi within which were 3 adult mites

and 12 eggs. The eggs were collected from the mold and placed in
a gelatin capsule with female parasites, but the parasites did not
approach.the mite eggs.

Coleoptera.

 

Chrysomelidae.

 

Crioceris asparagi (L.). Three replications of 133 asparagus

 

beetle eggs were tested at 3 different times. The parasites did
not approach the eggs. All but 15 of g, asparagi eggs hatched.

Crioceris duodecipunctata (L.). Thirty-two eggs of the spotted

 

asparagus beetle 24-36 hours old were tested in two replications
at different times. As in 9,.asparagi the parasites did not show
any interest in the eggs.

Lema trilineata (?). A.mass of 12 eggs of unknown age was found

 

in Beal Botanical Garden on the undersurface of leaves of sacred

17

datura plants (Datura meteloides). The species ranges from Texas

 

to California and northern Mexico. Thirteen other eggs less than
24 hours old which had been laid in a vial were also tested. The
'parasites approached the eggs several times and finally one of
the parasites appeared to oviposit in 3 of the 12 eggs.: IEEEE
larvae hatched from 2 of these 3 eggs. In the second trial of

13 fresh eggs the parasites approached the eggs several times

but they did not appear to sting them. No parasite developed
successfully. .Robert Anderson at Purdue (personal communication)

has had some development of Anaphes in Lema trilineata obtained

 

from New Jersey, but there is a suspicion that "Lema trilineata"

 

may contain several species. The "species" used in the present
work may not be the same as the New Jersey "species" and may not
be suitable.

Leptinotarsa decemlineata (Say). A total of 77 eggs of the

 

Colorado potato beetle, 24—36 hours old were tested in 4 dif-
ferent trials. \The parasites appeared to sting 8 eggs; all but
2 hatched normally. No parasites developed successfully.'
Trihabda g2, Seventy-nine,eggs were tested in 3 replications of
35, 15, and 29 eggs. The age of the eggs was 24-36 hours. The
eggs were laid on the upper surface of golden rod (Solidago§2:)
in cages in greenhouse conditions. ’The parasites did not have
any positive reaction to the eggs; 57 of the 79 eggs hatched.
The other 22 eggs did not hatch, probably because of the high
temperature and the low humidity during the time the work was

done.

18

b. Coccinellidae.

 

l. Adalia bipunctata L. Twelve eggs of unknown age of the two-

 

spotted lady beetle found as a mass on a maple leaf were tested
but no interest was shown by the parasite. Ten of the 12 eggs
hatched normally.

2. Coleomggilla maculata lengi (Timb.). Three replications totaling

 

76 eggs of this lady beetle were tested at different times. The
parasite did not approach the eggs.

3. Hippodamia convergens Guerin. A total of 62 eggs.of the con-

 

vergent lady beetle were tested with the same results as in
E, maculata.

4. Hippodamia lB-punctata Say. Sixty-nine eggs of the thirteen-

 

spotted lady beetle were tested. The eggs were laid on the
petri dish_cover and were 12-24 hours old. One parasite approached
the eggs but did not sting.

5. Unidentified eggs. A total of 15 unidentified coccinellid eggs,

 

24-36 hours old, were tested but without positive results.

7. Lepidoptera.

 

a. Noctuidae.

1. Trichoplusia_gi (an.). Three eggs of the cabbage looper were

 

found under the leaves of wild mustard. The parasites did not
approach the eggs.
b. Arctiidae.

l. Unidentified eggg. A total of 90 eggs of unknown age were found

 

on the under surface of the leaves of smartweed (Polygonum.§g.).
The eggs were spherical and laid in a mass. Although the para—

sites approached the eggs and passed over them several times they

19
did not sting them.

2. Haploaigg, Ten eggs reared from captive females were tested
with the parasites without success. The Haploa eggs were laid
as a mass, and all of them hatched.

c. Pyralidae.

1. Galeria melonella L. Thirty-nine eggs of the waxmoth of 12-24
hours old from Michigan State University stock were tested, but
the parasite did not show any interest in the eggs.

2. Ostrinia nubilalis (Hubner). Eggs masses of the European corn
borer were found beneath wild mustard leaves. The eggs were
laid in clusters of 14-20 and overlapped one another like fish
scales. Some of the tested eggs were fresh and some in the
"black head" stage. In no case did the parasites approach the
eggs.

d. Pieridae.

l. Colias eurytheme Boisduval. Seventeen eggs of the alfalfa
butterfly, 0-24 hours old were tested, but the parasites did not
approach the eggs. The Q, eurytheme eggs were laid on a weed
leaf petiole placed in a glass jar. All the eggs hatched.

2. Pieris rapae (L.). Thirty eggs of the imported cabbage worm

 

laid on leaves of wild mustard were tested. During the tests
some of the eggs were-removed from the plants and placed in a
gelatin capsule with the parasites. Some other eggs were placed-
in a gelatin capsule without being removed from the plant. In
both cases the eggs were not approached by the parasites. All of

the eggs hatched.

20

 

e. Saturniidae.

l. Antheraea polyphemus (Cramer). A total of 42 eggs of the poly-

 

phemus moth were tested. Ten of those eggs were 0-24 hours old
and the rest of unknown age. The eggs were laid in a glass jar.
The parasites did not approach the eggs. The eggs did not hatch.

8. Hymenoptera.

 

l. Unidentified eggs. Three eggs of an unknown species were found

 

on the underside of the leaf of Polygonum_§g. The eggs were in-
serted in the leaf epidermis, were of a transluscent color and of
unknown age. The parasites did not approach the eggs.

9. Homogtera.
a. Cicadellidae.

 

l. Scaphytopius magdelensis (Prov.). Twenty-seven eggs on blue-

 

berry, obtained from Michigan State University stock, were
tested but the parasites did not show any interest in them.

2. Unidentified eggg. Twelve eggs, probably Cicadellidae, were

 

 

found in the stem of Polygonum g2: The eggs were elongate and
inserted fully into the stem. The outer end of the egg was
pointed with a black spot at the end. At a small distance from
the outer end there were two black eye-like spots. The para—
sites did not approach the eggs in the stems nor when they were
dissected out of the stems and placed on slides. The eggs on
slides had not hatched after 12 days. At that time they were
covered by a deep layer of fungus mycelium.

10. Hemiptera.

a. Miridae.

l. Lygus pratensis (L.). Nineteen eggs of the tarnished plant bug

21
were found in petioles and near the midribs of sugar beet leaves.
The eggs were placed in a gelatin capsule with the parasites
without removing them from the plants. Eggs were also tested
after they had been removed from the tissues. In no case was
an approach of the eggs by the parasites observed. The tarnished
plant bug eggs did not hatch because the juicy sugar beet leaves
became covered with mold and both plant and eggs rotted. The
eggs which were removed from the plant tissue dried out in the
Petri—dish.

ll. Diptera.
a. Cecidomyiidae.

 

1. Mayotiola destructor (Say). The Hessian fly eggs-were obtained
from a Michigan State University culture on barley plants in
greenhouse. The eggs were laid in the grooves of the upper sur-
face of barley leaves. About 420 eggs 24 hours old were tested

but the parasites did not show any interest on them.

Discussion

 

The results obtained in the present work showed that none of
the tested eggs were suitable for the development of the parasite,

Anaphes flavipes .. Many of the tested species belong to families dif-

 

ferent than that to which the CLB belongs, so the shape, size, and
general appearance of the eggs is different from CLB eggs.

As far as the eggs of species belonging to the family Chrysomel-
idae are concerned, although the parasite showed interest, progeny did

not develop. In the case of the Colorado potato beetle, Leptinotarsa

 

decemlineata, and Lema trilineata where the parasite stung a few of

 

 

22
the eggs but no emergence of the progeny developed, two things might
have occurred. First, the parasite may not have laid eggs, possibly,
because chemicals or physiological factors inhibited oviposition.
Second, the parasite may have oviposited, but the host was unsuitable
for parasite progeny development. Salt (1938) demonstrated that even
if a parasite can reluctantly or with difficulty attack the unnatural
host, the progeny may not develop.

Anaghes did not approach the tarnished plant bug eggs although
another egg parasite, Anaphes ovijentatus (Crosby and Leonard), para-
sitises the eggs of the plant bug, Lygg§_hesperus Knight., in California
(Romney and Cassidy, 1945).

From these results obtained by testing the eggs of the above
species it is not certain that Anaphes is restricted to eggs of the CLB.
Many more eggs of different species should be tested before any such

statement can be made.

23

Table 1. Tests of eggs as possible alternate hosts of the cereal leaf
beetle egg parasite Anaphes flavipes

 

 

 

Number Age of Reaction Number of Hatched eggs

 

 

 

 

 

 

 

 

 

 

 

 

 

. of eggs of parasite eggs Number of:
SpeCIes tested , exposed in to eggs rapparently NOt
' eggs days stung Stung Stung
1. Unknown eggs a b c
from soil 10 ? NI 0 0 4
2. Unknown eggs
.from pine needles 6 ? NI 0 0 6
3. Unknown eggs on
mustard plant mass ? NI 0 0 0
4. Spider eggs 12 ? ' NI 0 0 .10
5. Mite eggs 12 . ? NI 0 0 7
6. Crioceris asparagi_ 100 24—36 NI 0 0 85
7. Crioceris
duodecipunctata 32 24-36 NI 0 0 22
8. Lema trilineata l2 ? AS 3 2 9
9. Leptinotarsa
decemlineata 77 24—36 AS 8 6 69
10. Tri habda £2, 79 24-36 I 0 0 57
ll. Adalia
bipunctata 12 ? NI 0 0 10
12. Coleomegilla
maculata 76 24-36 NI 0 0
l3. Hippodamia
convergens 62 24-36 NI 0 0
l4. Hippodamia
lB-punctata 69 12-24 I 0 0
15. Unknown Coccinellid
eggs 15 24-36 NI 0 0
16. Trichoplusia.gi_ 3 ? NI 0 0
l7. Unidentified eggs
of Arctiidae 90 ? NI 0 0
.18. Haploa g2, 10 ? AS 0 0 .10
19. Galeria
melonella 39 24 ' NI 0 0 3o
20. Ostrinia -
nubilalis mass ? NI 0 0 12

21. Colias erytheme 17 24 N1 0 0 .17

 

24

Table 1. Continued.

 

Number Age of Reaction NUmber of Hatched eggs

 

 

 

 

 

. of eggs of parasite eggs Number of:
SpeCIES tested exposed in to eggs apparently Not
eggs days stung Stung Stung
22. Pieris rapae 30 2a NIb 0 0° 30
23. Antheraea 10 24 NI 0 0 0
polyphemus 32 ? NI 0 0 0
24. Unidentified eggs
of Hymenoptera? 3 ? NI 0 0 3
25. unidentified eggs
of Cicadellidae? 12 ? NI 0 0 0
26. Scaphytopius
magdelensis 27 ? NI 0 0
27. Lygus pratensis l9 ? NI 0 0 0
28. Mayotiola
. destructor 420 24 NI 0 0

 

 

a
? indicates unknown age.

bNI: no interest, AS: apparently stung, I: interest.

cIn no case did parasites emerge from apparently stung eggs.
Oviposition and emergence of parasites used for tests was normal in all
cases on the control CLB eggs.

PART III

THE ACCEPTABILITY AND POTENTIAL USE OF BIOLOGICAL CONTROL

AGENTS OBTAINED FROM SPECIES OTHER THAN THE TARGET SPECIES

Introduction

 

The speed of transportation in recent years and the trade
throughout the world has increased the chances of introduction of in-
sect pests from one country to another. Also, the large movement of
commodities has been the means whereby many peSts have been able to
extend their range in the same country. One of the reasons newly
introduced insects become pests is because the natural enemies para-
sitizing or preying upon them in their native land have not followed
them to their new location. The separation of harmful insects from
their natural enemies is not an uncommon occurrence and the most suc-
cessful biocontrol programs have been based upon the-reuniting of
introduced exotic pests with their parasites and predators (van den Bosch
and Telford, i§_DeBach 1964).

In biological control work the objective is to reduce the insect
pest's damage to a non-economic level. This can be accomplished by
using biological agents such as parasites, predators and microorganisms.
Some higher organisms such as amphibians, birds, snails have been re-
ported to be utilized as biological agents (Metcalf,1951; Franz,1961),
but the present review will deal only with.the utilization of the insect
parasites and predators, and the so-called microbial insecticides,

25

 

26
which have been responsible for the great majority of the successes in
biological control of insect pests.

Relatively few attempts have been made in the past to control
native pests with introduced parasites and predators, because it was
generally believed that a pest is best controlled by native organisms.
In the past, parasites, predators and biotic mortality factors of
allied species were sought only when all else failed (Pimentel, 1963).
Also, it has been thought that the possibilities of biological control
are limited in each country to those pests which are of foreign origin.
But there is a growing realisation that biological control may be
effectively applied to native pests too (Doutt, i_r_1_ DeBachl964). It
is not at all uncommon for pests to acquire effective natural enemies
from allied native insect hosts. The present review will deal with
the most outstanding examples of biological control by introduction of
natural enemies from related species as well as with the introduction
into new areas of native enemies with a limited distribution.

The destruction of the native Bermuda cedars by the accidentally

imported diaspine scales, Lepidosaphes newsteadi (Sulc.) and Carulaspis

 

 

visci (Schrank), and the destruction of the chestnuts in the Uhited

States by the chestnut blight, Endothia parasitica (Murr.) And. and

 

And., from oriental sources are good examples which suggest that native
weeds and trees can be suppressed by the introduction of biotic agents

from foreign sources (Doutt and DeBach iE_DeBach 1964).

Use of parasites and predators

 

It is believed that certain insects have become-more harmful in

their new environment because their natural enemies could not adapt

27
with equal facility even if established, and the native enemies are
more specific and do not attack the introduced species (van den Bosch
and Telford, iE_DeBach.l964).
Clausen (1956) has given examples of the successful use of

native parasites. The squash bug, Anasta tristis (Deq.), occurs

 

throughout the united States,.but a strain of its principal parasite

Trichopoda_pennipes (F.), was limited to the Eastern region of NOrth

 

America. When introduced and colonized in the Pacific Northwest it
gave successful control. A second example given by the same author is

that of the woolly apple aphid, Eriosoma lanigerum (Hausm). This pest

 

has extended its range from the Northeastern portion of the United

States to the Pacific coast, but its native parasite,_Aphelinus mali

 

(Hald), was left behind. By colonization and establishment of the
parasite in the new area the control was satisfactory. Clausen (1956)

also reported that the parasite Tetrastichus asparagi wad., which

 

attacks the asparagus beetle, Crioceris asparagi (L.), in the eastern

 

United States had a limited distribution, but when it was introduced
into the Pacific northwest it became an effective control agent there.
Some native parasites are quite specific and often do not

attack introduced species from foreign countries. However, Brunson
and Allen (1944) give a good example of a native parasite which became

effective against an introduced pest. The native parasite, Macrocentrus

 

ancylivorus, of the strawberry leaf roller, Ancylis comptana fragariae

 

 

(W. and R.) adapted to a serious introduced pest, the Oriental fruit

moth, Grapholitha molesta (Busk), and gave very substantial control.

 

Another example similar to the above is that given by Howard

and Fiske (1911), concerning the behaviour of certain hyperparasites

28

of Apanteles fulvipes (Ha1.). They found that the.cocoons.of_é.

 

fulvipes, which.is a parasite of the gypsy moth, were attacked by 25
species of hyperparasites in Europe and Japan. Great care was taken
to screen out all these hyperparasites from America where the parasite
was.introduced and established. However, after the establishment of
the species it was found that several native hyperparasites attacked
.it to practically the same extent as in its native home.

Is it possible to use parasites or predators obtained from
species or genera closely related to the pest to control an insect
pest? There are some examples through the literature which give a
positive answer.

A tachinid fly, Ptychomyia remota Aldrich, a parasite of the

 

moth Artona catoxantha Hmps. in Malaya, was introduced in Fiji and

 

successfully controlled the coconut moth, Levuana iridescens (B. and

 

B.), (Tothill, Taylor, and Paine, 1930). Both hosts belong to the
same family Zygaenidae, but the two genera do not have close simi-
larities.

Doutt (1950) found that the Japanese parasite Anabrolepis

 

extranea Timb. successfully controlled the red coconut scale, Furcasgis
oceanica Lind., when introduced in the Caroline Islands. of Ulethi,
Atoll, Yap and Palau. The native host of the parasite is the scale

Ceroplastes rubens Maskell. (Yasumatsu and Tachikawa, 1949). Doutt

 

(1951) showed that initial heavy infestations on gardenias in the

greenhouse by the mealybug, ngudococcus_citri (Risso), could be re—

 

duced by using natural predators such as the lacewing Chrysopa

californica Coq., and the encyrtid Anggyrus kivuensis Comp. instead of

 

 

its most common predaceous Coccinelid, Cryptolaemus montrouzieri,

 

29
which cannot act under greenhouse conditions, because of the extreme
humidity. Fleschner (1958) has reported that the citrus.red mite,

Metatetranychus citri (MbG.), an Oriental pest introduced into

 

California, was satisfactory controlled by the native predators, the

coccinellid Stethorus picipes Casey and the staphylinid Oligota oviformis

 

 

Casey. Marshall (1953) found that the apple mealy bug, Phaenococcus

 

aceris (Sign.), introduced from Europe, became a serious pest in

British Columbia. The parasite Allotropa utilis Mues., a native para-

 

site in eastern Canada had proved to be effective against the mealybug
on the east coast before being introduced to the west coast.

The coccinellid beetle, Enochomus quadripustulatus,

 

imported from Italy into California to control certain Coccidae,.was
found to be capable of checking heavy infestations of the native woolly

apple aphid, Eriosoma lanigerum (Hausm.), in some parts in California.

 

This is valuable because it can supplement the native parasite of the.

aphid, Aphelinus mali (Hald.) Michelbacher and Borden (1944).

 

From the above examples it is clear that parasites and/or
predators obtained from either the native host species or from allied
species can sometimes provide satisfactory to successful control of
insect pests of native or foreign origin.

Why have native and introduced pests been successfully controlled
by parasites and predators obtained from species different from the
target species? Pimentel (1963) states that the severe feeding pres-
sure exerted by parasites from allied species on their new hosts is
due primarily to the new association between parasite and host. A
parasite which can invade a new host species usually inflicts extreme

damage on that host. In contrast, parasites which have evolved with

30

their host seldom increase to outbreak levels on the host because a
stable and balanced economy (homeostasis) is developed between the
interacting species. He believes that the use of native parasites
does not provide the expected control, because this ecological homeo-
stasis exists between host and parasite.

Peterson (1955) has reported that the European corn borer became
a pest of major importance in Guam. Several parasites were introduced

from the United States and Japan. One species, Dydella stabulans

 

grisescens R.D., became established and for a number of years success-

 

fully controlled the corn borer, but then seemed to disappear. The
factors responsible for this disappearance are not known. Pimentel
(1963) suggests that a sort of resistance of the host to the parasite
may develop in this.kind of association and the disappearance of the
parasite in Guam may be due to this phenomenon, although the actual

reasons are unknown (Peterson, 1955).

Use of microorganisms

 

Steinhaus (1954) has pointed out three attributes characterizing
microbial agents capable of causing epizootic diseases in insects and
thereby reducing their populations. These are: (1) The capability of
the agent to invade and infect the insect host. (2) The capacity to
survive. (3) The capacity to spread from one insect host to another.
Recent years have seen a rapid development of the field of insect
pathology and the knowledge of microbial diseases of insects is
rapidly accumulating.

In the present review the examples of microbial control will be

restricted almost entirely to those manipulated by man and to those that

31
appear to be of outstanding significance and importance in biological
control, since many_papers on insect pathology have recently appeared
and it is not possible to adequately treat all of them.

The use of viruses. There are five groups of virus diseases of insects:

 

nuclear and cytoplasmic polyhedroses, granuloses, polymorphic inclusion
viruses and the non—inclusion viruses (Tanada 1959). Some of these
diseases, such as the nuclear polyhedrosis of the silkworm, were known
as diseases several centuries ago, but were not recognized as virus
diseases. Recently (Steinhaus ig_DeBach 1964) recognized about 250
viruses infective to 175 insects and arachnids. About 170 of these are
nuclear polyhedroses, 30 are cytoplasmic polyhedroses, 35 granuloses,
8 are known that do not appear to be associated with inclusion bodies,
and a few infections are suspected to be caused by viruses, but for
which there is no definite proof.

Bird (1953) used a polyhedrosis virus obtained from Sweden to

control the European pine sawfly, Neodiprion sertifer (Geoffrey),

 

attacking the Scotch-pine plantations in southern Ontario. The same
author found that this disease was so effective that the use of in-
secticides was no longer necessary. The same virus has been used
successfully for the same insect in the United States and in Europe
(Breny_l951).

Polyhedrosis viruses have been applied against the alfalfa

caterpillar, Colias eurytheme Boisduval, in California by Steinhaus

 

and Thomson (1949) and Thomson and Steinhaus (1950). They showed that
the virus applied as a spray is capable of causing infection and re—
ducing the population of the alfalfa caterpillar to sub-economic

levels.

32
Tanada (1956) successfully controlled lepidopterous pests of

crucifers in Hawaii, including the imported cabbage worm, Pieris rapae

 

(L.), the cabbage webworm, Hellula rogotalis (Hulst.), the diamond

back moth, Plutella maculipenis (Curtis), and the cabbage looper,

 

Trichoplusia_gi (an.), by using a granulosis virus, Bergoldia

 

virulenta Tanada. The virus was the same one which attacks the alfalfa
caterpillar (Tanada, 1953).

The use of rickettsiae. Recently it has become clear that rickettsiae

 

are capable of causing fatal infections in insects (Steinhaus, £5
DeBach 1964), and they would be useful as biological control agents.
Some rickettsial infections have been reported such as the fatal "blue"

disease in the larvae of the Japanese beetle, Popillia japonica New.,

 

(Rutelinae) which also affects the larvae of Melolontha vulgaris L.,

 

(Melolonthinae) (Angus, 1960). Both insects belong to the Scarabaeidae.

The use of bacteria. Hawley (1952) has reported that the Japanese

 

 

beetle, Popillia japonica New., a serious pest introduced into the
northeastern united States from Japan, was seriously affected by the

bacterium Bacillus popilliae Dutky, which was first found in the

 

northeastern part of the United States. The discovery of Bacillus
popilliae as the causative agent of milky disease in the Japanese
beetle gave additional encouragement for the utilization of it to con-

trol other insects. The European chafer, Amphimallon majalis (Razoum.),

 

has been found to be susceptible to "milky" disease and according to
Tashiro and White (1954) it might be of value in the biological control
of this insect.

Another example showing that pathogens can be obtained from non-

target species is that given by Steinhaus (1951) for the control of

33

the alfalfa caterpillar, Colias eurytheme Boisd., by Bacillus

 

thuriggiensis Berl. The pathogen was originally isolated from larvae

 

of the Mediterranean flour moth, Anagasta kfihniella (Zell.), in Europe

 

in 1911. Since that time, it has been subjected to repeated tests to
determine its potential as a microbial pathogen, and a large number

of insects, mostly Lepidoptera, have been found to be susceptible to

 

it. Heimpel (1967) has compiled a list of various insect species and

their sensitivity to an exotoxin from_§. thuringiensis var.

 

thuringiensis Berl.

 

The use of nematodes. Little work has been done with nematodes for

 

insect control. However, nematodes may provide a significant number
of effective agents because of the large numbers which are internal
parasites of insects. Also, nematode parasites are particularly in-
teresting as control agents because their motility allows them greater
opportunities than some other pathogens to contact the host (Tanada
1959).

Insect pathologists in the U.S. Department of Agriculture
laboratory at Beltsville, Maryland, isolated a parasitic nematode from
larvae of the codling moth. The nematode showed a very wide host
range and caused a fatal infection in many insects. Among the insect
species found to be very susceptible were the wax moth, Galleria

melonella L., the Mediterranean flour moth, Anagasta kfihniella Zell.,

 

sawflies Neodiprion 33., and the European corn borer Ostrinia nubilalis

 

 

(an.) (Dutky and Hough, 1955). The nematodes were found to contain
an associated bacterium. The bacterium does not infect insects

readily when ingested, but when introduced by the nematode into the

34
body cavity of the host, it flourishes and not only kills the insect
but also serves as food for the nematode.
Chamberlin and Dutky (1958) used a semiparasitic species of

Neoaplectana known as "Dutky's" nematode or DD—136 for the control of

 

the tobacco hornworm. This was first observed in the codling moth by
Dutky (1954). The DD—136 acted as a carrier of a bacterium which
actually killed the hornworms. The results in the field test gave a
reduction of 80% within 3-4 days of the hornworm population. working
with the name nematode Schmiege (1963) reported the advantages and the
disadvantages of the nematode for the control of some forest insect

pests such as the introduced pine sawfly, Diprion similis (Hartig.),

 

jack-pine budworm, Choristoneura_pinus Freeman, the European pine

 

shoot moth, Rhyacionia buoliana (Schiff.), and some others. So far

 

no complete control has been achieved by using the above nematode,
but it is possible that additional tests will reveal situations where
the nematode can be used for successful control of a number of its
susceptible hosts (Hall, i§_DeBach 1964).

The use of protozoa. Tanada (1959) suggests that although protozoa

 

offer promise in biological control, their application is limited be-
cause they cause chronic rather than acute infections.' According to
Tanada (1959) Weiser has listed some protozoa which show promise in
biological control work. weiser also showed that the amounts of

chemical insecticides to kill Otiorrhynchus ligustici L., the sugar

 

beet weevil, are reduced when the insect is infected by a microsporidan

pathogen Nosema otiorrhynchi Weiser. Zimmack et al. (1954) found that

 

the microsporidian pathogen Perezia pyraustae Paillot, infected the

 

 

European corn borer, Ostrinia nubilalis (an.) in the North Central

35
states. The infected insects laid fewer eggs than the healthy ones.
The protozoan parasite reduces the fecundity of the female and this
probably helps in the control of the pest.

The use of fungi. Fungi as biological control agents have seen rather

 

limited use because of their dependence on appropriate humidity condi—

tions. Certain groups, such as Entomophthorales, appear to have

 

potential use as biological control agents. Because of their high

 

parasitic nature species of Entomophthorales have played an important

role in reducing populations of the spotted alfalfa aphid, Therioaphis

 

maculata (Buckton), in California (Hall and Dietrich, 1955). TWO of
the fungi have been isolated or observed from aphids collected from
India, Iraq and Israel. This indicates that the fungi are contributing
to the control of the spotted alfalfa aphid in its native home (Hall
and Dunn, 1957).

Among the Fungi Imperfecti, a classic example of effective

microbial control is the use of a strain of Beauveria bassiana

 

(Balsamo) Vuillemin isolated from an unidentified species of Crambus

from Oregon, and used against the sod webworm, Crambus bonifatellus

 

(Hulst.) (Hall, 1954).

By bassiana was known to attack the silkworm, and since 1835
the disease was considered to be noncontagious in nature. One of the
first attempts to use B. bassiana as biological control agent was made
by Tangl in 1893 in Europe for the control of the larvae of the nun

moth, Lymantria monacha L. In the United States the fungus was intro-

 

duced from Manchuria on larvae of the European corn borer (Lefebvre,
1931). Paschke (1965) noted an infestation in the cereal leaf beetle,

_9. melanopa, by the fungus Beauveria bassiana. There appeared to be

 

36
definitive strain differences between various isolates. The author
suggested that single spore isolations of these strains may provide a

particularly virulent strain for the control of Q. melanopa adults.

Discussion

 

From the examples given above it is apparent that in B.C. work
it is very difficult to predict whether or not B.C. agents obtained
from target species or from non-target species will be most successful
for the control of a native or introduced pest.

What criteria must the investigator have for selecting biological
control agents obtained from species other than the target species?

DeBach (1964) has presented various hypotheses as to why par-
ticular natural enemies controlled or failed to control particular hosts
in particular areas. Some of these hypotheses are: -l) Parasites are
better than predators (or vice versa). 2) Monophagous enemies are
better than polyphagous (or vice versa). 3) Many species of enemies
attacking one host are better than one. 4) The natural enemy should
come from the same host in the country of origin. 5) Natural enemies
should be imported from areas ecologically equivalent to the area of
introduction. 6) Immigrant pests offer best opportunities for biological
control.

Although many examples support these hypotheses, there are also
numerous instances in which the hypotheses have not been supported.

In support of the hypothesis (4) Turnbull and Chant (1961) stated that
the relative success of a parasite species against a pest in its native
environment is a reasonable basis to predict its success on the same

pest in a new locality. They pointed out that a parasite which plays

37
an insignificant role in its native locality may succeed in a new
area because it may be freed from the interference of competitors that
are better adapted than itself to the native environment. An example

of this is Opius ilicis, a rare parasite of the holly.leaf miner in

 

England. The parasite was introduced into the British Columbia main-

land and vancouver Island. On vancouver Island Opius ilicis was of

 

minor importance, whereas Epilampsis gemma, another parasite introduced

 

from England, caused 90% of the total parasitism. But on the mainland,
_E_. m was of minor importance and _(_). ilicis became the dominant
parasite of the pest (SO-90% parasitism).

Pimentel (1963), in regard to the same hypothesis, stated that
imported parasites, predators and pathogens from allied species from
different habitats can be used to control introduced pests, and may be
effective against native pests. In the last case he pointed out that
no ecological homeostasis is involved, so the association between
parasite and host, or predator and prey is new.

With regard to hypothesis (3)-—whether or not many biotic agents
are better than one--Turnbu11 and Chant (1961) stated that the more
species of biotic agents attacking the pest the sooner competition
between the parasites will start and the more severe will be its
effects on all biotic agents. Therefore, they maintain that the best
results would be obtained by introducing a single efficient organism
without competitors, and if it fails, then replace it with another one.
Another point of viewis Smith, 1929), that the importation of a
second parasite would add to the effectiveness of the first. Possibly
the intrinsic superiority of one parasite over another may result in

the waste of some parasites, but this effect is an insignificant factor

38
in the comparative field efficiencies of the two competitive forms.
Also Bartlett and Ball (1964) have shown that the intrinsic competitive

superiority of Metaphycus luteolus (Timberlake) over Microterys flavus

 

 

Howard in the laboratory which are both internal gregarious parasites

of Coccus hesperidum L. does not prevent the second parasite-from

 

assuming overwhelming dominance in the field.

There are some exceptions to hypothesis 69 that the climate of
the native location and that.of the land of introduction must be
similar for the establishment and succeSS of the natural enemies. For

example the egg parasite of Gonipterus scutellatus Gyll. was obtained

 

from a subtropical area of Australia and spread from areas of a similar
climate to more temperate parts of South Africa (Tooke, 1953). Also

Comperiella bifasciata How and Prospatella perniciosi Tower., both

 

 

successful parasites of the California red scale were established in
regions in California where the climatological conditions are quite
different from the tropical areas where the parasites originated
(DeBach, 1963).

All possible ways should be tried to control the cereal leaf
beetle. Research aimed at finding parasites from allied species could
give satisfactory results. Introduction of all the European parasites,
predators, and pathogens of CLB should be attempted. But in addition,
biological control agents from species related to the CLB from areas
in the world ecologically equivalent to the area in Europe where the
CLB is found is desirable.

Satisfactory control could result from the introduction of

parasites obtained from allied species such as Lema_oryzae Kuwayama

 

 

 

(Kuwayama,l935), Oulemg tristis, and Oulema flavipes in Japan. The

39
following are suggested as good possibilities for trial. Townes,

Mbmoi and Townes (1965) refer to some ichneumonid parasites on Oulema

 

melanopa and the above species related to it. Bathytrix kuwanae Sonan,

Pezomachus lemae Sonan, and Habrocryptus ruficoxatus Sonan, are reported

 

 

to parasitize "Oulema melanopa" (probably a misidentification of

 

Oulema oryzae). Nesopimpla maranyae Kuwayama, is reported as a para-

 

 

site of Oulema tristis and Oulema oryzae.

 

 

Parasites may also be obtained from Oulema gallaeciana, a close

 

 

relative of Q. melanopa in Europe. Anaphes nipponicus Kuwayama, an

 

egg_parasite of_9. oryzae in Japan possibly will be useful in the con-

trol of the pest in the United States.

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40

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