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LEPIDOPTERA, Epipyropidae -- <Images>
& <Juveniles> All Epipyropidae are true parasites (not parasitoids) mainly on
Homoptera of the family Fulgoridae, and occasionally from Cicadellidae and
one species occurs on Cicadelidae in Japan.
The family is abundant in Australia, Perkins (1905b) having observed
millions of cocoons on the foliage of Terminalia
in Queensland, which gave the appearance of a heavy infestation of Pulvinaria. A number of species occur in India also. Westwood (1876) observed larvae of Epipyrops anomala Westw. on the bodies of Fulgora candelaria L.
and concluded that they were feeding mainly on the cottony secretion covering
the body of this insect. The larger
larvae of E. fuliginosa Tams scraped the side of the host body with mandibles,
probably feeding on secretions (Subramaniam 1922). No injury seemed to be inflicted, and the leafhoppers looked
healthy long after the larvae had abandoned them. However, later observations by various researchers showed that the
larvae of some species are definitely parasitic and that the scraping and removal
of wax are incidental to the efforts of larvae to penetrate the host body
wall. Clausen (1940) stated that one
of the main arguments to support a parasitic relationship is that fact that
the hosts of some species have no wax body covering. In such cases it was asserted that feeding
may take place on the honeydew, which is produced in abundance. The larvae have very long slender
mandibles more fitted for penetrating the body wall than for use in feeding
on external secretions (T. B. Fletcher cited by Clausen, 1940). Krishnamurti (1933) studied E.
eurybrachydis Fletcher, that
develops as a solitary or gregarious external parasite on the adult females
of the fulgorid, Eurybrachys tomentosa F. in India. Nymphs or male adults are not
attacked. The eggs are a dirty
gold-yellow, oval in form, and measure 0.5 mm. long. They are laid in series of irregular rows
on the foliage of the host's food plant.
Each female produces a total of 400-500 eggs. Incubation is complete in 6-8 days, and
the young larvae wander about on the foliage in search of hosts. They are often observed in an erect
position, clinging to the leaf margins by the prolegs, and waving back and
forth as if waiting for a host. There
are 5 larval instars, the 1st of which is 1.25 mm. long with 13 body segments
which decrease in width toward the back.
The legs are short, 5-jointed, and end in a curved claw; mandibles are
bidentate. Younger stages are found
on different parts of the host body.
Older individuals are usually beneath the wings, at one side of the
median line, and they lie with the head directed toward the back. The presence of one of these parasitic
larvae on the fulgorid body is always indicated by the elevated position of
the wing on one side. The mandibles
are embedded in an aperture in the abdominal integument. The effect of parasitism on the host is
slight, for the amount of body fluids abstracted is comparatively small in
relation to the size of the host and is manifested only by a small amount of
weakness. Adult life is not much
shortened, nor is egg production reduced.
The parasite's larval feeding period is 42-45 days and adult life 8-10
days. When feeding is finished, the
mature larvae, not 7-8 mm. long, leaves the host and spins its oval,
milky-white cocoon on the underside of a twig. The pupa emerges partly from the cocoon just prior to the
issuance of the adult moth, and oviposition begins 24-36 hrs. after emergence
from the cocoon. Other species that have been studied in smaller detail are Agamopsyche trenodes Perk. (Perkins 1905b) and Epipyrops doddi Roths.
(Rothschild 1906). There is
considerable variation with regard to the sex and stage of the host
attacked. A. trenodes attacks the
adults of both sexes of Cicadellidae.
However, other species of the family have been found on nymphs as well
as adults (Perkins 1905b). Feeding of
the larvae seems to produce little or no effect on the host. However, in A. trenodes the
parasitized leafhoppers show a distinctive collapse of the abdominal dorsum,
and death may occur the day following the departure from the host (Clausen
1940, citing Koebele). This is also
thought to be true for E. barberiana Dyar, developing on Ormenis pruninosa Say in North America. Epipyrops larvae
assume a rather uniform position on the body, this being on the dorsum of the
anterior portion of the abdomen beneath the wing, and with the head directed
toward the rear. The tip of the
abdomen in E. fuliginosa is apparently attached to the side of the host
thorax. Epipomponia nawai Dyar,
attacking adult Cicadidae in Japan, is small compared to the host and is
found on the thoracic venter or on the venter or dorsum of the abdomen. The fact that the larvae retain a fixed
position on the host further supports the true parasitic relationship
(Clausen 1940/62). The disk-like eggs of Agamopsyche
are laid in large batches on dead grass and leaves in the same environment in
which cocoons are found (Perkins 1905b).
However, there is little doubt that the eggs of other species are also
laid in clusters on foliage or twigs in the vicinity of feeding hosts and
that the 1st instar larvae either search for their hosts or wait until they
pass nearby. There is a relatively short life cycle, from egg to adult of ca.
1 month. About half of this time is
spent as larval feeding. The cocoon
stage of E. doddi takes 13-17 days and that of E. anomala 9 days. Perkins (1905b) found that Agamopsyche is unisexual with no males
known. Fertile eggs were produced by
virgin females under cage conditions.
However, males are known in species of several other genera. First instar larvae of Epipyropidae have adaptive characters
developed as a result of their unusual life style. The very slender, tapering body with comparatively strong legs,
is obviously an adaptation to free-living during the host searching
phase. This larva shows a tendency
towards assuming a planidium form found in other orders, which has been
developed to meet very similar requirements.
It is able to stand erect by the use of anal prolegs, a behavior that
is general among larvae of this type in many other families and orders
(Clausen 1940/62). After the first
molt, the legs become much reduced and the later instars are almost sessile. The head and mouthparts of all instars are
markedly modified as a result of the manner of feeding. The body becomes either oval or almost
circular in outline, and a distinctive form is assumed. This is accentuated by the presence of an
extensive waxy covering over the body.
In Agamopsyche, it was
observed that the larger larvae were able to suspend themselves from the host
body by a silken thread. The cocoons
are white, with a mealy surface.
There is considerable variation in form and surface
ornamentation. Usually there are many
longitudinal ridges. The cocoon of an
undetermined species of epipyropid was observed by Koebele in Australia was
rosette-like and nearly circular, with several vertical lamellae arranged
concentrically about the more solid center.
The empty pupal case is found partly extruded from the cocoon (Clausen
1940/62). References: Please refer to <biology.ref.htm>, [Additional
references may be found at: MELVYL
Library ] |