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File: <cynip1.ima.htm> [For educational purposes only] Terminology Glossary <Principal Natural
Enemy Groups > <Citations> |
Immature Stages
of Cynipoidea
Immature stages of Cynipoidea were discussed in
detail by Clausen (1940), as follows: The Egg.‑‑The eggs of
the parasitic members of the superfamily are uniformly of the stalked type,
with the stalk, which is situated at the anterior end, ranging in length from
less than that of the main body, as in Charips
sp. (Fig. 126A), to several times its length. That of Figites
anthomyiarum (Fig. 128A) is
elongated and somewhat constricted in the middle and has a stalk of about
equal length. In Eucoila keilini,
the stalk is twice the length of the egg body, and in Ibalia leucospoides
it is about four times as long. The
chorion is thin and transparent and without surface ornamentation. First‑instar Larva.‑‑The
known first‑instar larvae of the superfamily are of several distinct
types. The "polypodeiform"
larva of I. leucospoides (Fig. 127A) is
unusually elongated, with a relatively large head, which is somewhat
flattened dorsoventrally and is provided with falcate mandibles. Of the 13 body segments, all except the
last bear a pair of fleshy, finger‑like processes ventrally, which are
of uniform length. There are no
integumentary spines or setae. The
last abdominal segment is prolonged into a dorsally curved tail equal in
length to the four preceding segments. Please CLICK on
picture to view details:
The first‑instar
larvae of the several genera of Eucoilinae that have been described are
distinctive and readily recognized and have been designated as
"eucoiliform." The
essential characters of this larval type that distinguish it from the
polypodeiform are the long, paired, fleshy ventral processes on the thoracic
segments only and an exceptionally long tapering tail. In Eucoila
keilini (Fig. 127B), the
head is large and somewhat conical, and the body segmentation is
indistinct. The fleshy thoracic
processes are about half the length of the body and taper to a blunt
point. The posterior segments of the
abdomen are very much narrowed, being only very slightly wider than the base
of the tail, and the tail itself is appreciably longer than the thoracic
processes, is curved ventrally, and terminates in a sharp point. The segment immediately preceding the tail
bears a fleshy conical lobe on the median ventral line. The integument of the posterior abdominal
segments bears numerous short sclerotized spicules. The larva of Cothonaspis rapae
described by James and Malchanova is similar to that of Eucoila. There are
at least seven distinct abdominal segments in addition to the two or more
that make up the tail, and the latter organ is nearly as long as the entire body. There are a few setae upon the thoracic
processes, and the distal third of the tail bears numerous spines. The eucoiliform larva of Kleidotoma marshalli figured and described by James has 12 apparent
body segments, and the body is much more slender than that of Eucoila or of Cothonaspis. The head is large, with the mouth opening
distinctly ventral. The fleshy
thoracic processes are much shorter, being equal only to one segment in
length, and they bear no setae. Stout
setae are present on the distal portion of the tail. The anal opening is indicated on the
dorsum of the eighth abdominal segment. The first‑instar larva of Figites anthomyiarum (Fig. 128B) is modified eucoiliform the
thoracic processes being even more reduced than in Kleidotoma with
the prothoracic pair only as long as wide, and the tail is short, almost
cylindrical, and bluntly rounded rather than pointed at the tip. The segmentation is distinct, and the 12
body segments preceding the tail bear fleshy spines on the dorsum, these
being largest in the mid‑abdominal region. In the Charipinae, the only first‑instar
larva that was described by 1940 was that of Charips sp. (Fig. 126B) by Haviland. This larva has few characters in common
with other members of the family and must be considered as a modified caudate
form. The head is large, equaling the
thoracic segments in width, and is produced anterioventrally into a conical "proboscis." There are three pairs of sclerotized
"nodules" ventrally and one pair dorsally, which presumably are
sensory organs. The mandibles are
long and slender. There are 13 body
segments, of which the first 12 diminish gradually in length and width
caudad. The last abdominal segment is
broad at its base, tapers sharply, and terminates in a cylindrical, ventrally
directed tail. This last segment is
equal in length to the 9 abdominal segments preceding it. The anal opening is large, situated
dorsally at the base of the last segment, and encircled by a sclerotized
ring. The head, and the body segments
except the last, are heavily sclerotized, and each of the body segments
telescopes into the one preceding it. None of the first‑instar
larvae of the family that has been studied possesses any indication of a
tracheal system, and respiration is consequently by diffusion only. Second‑instar Larvae. --The
second‑instar larvae of the Cynipoidea reveal differences that are
almost as great as those in the first instar. In Ibalia, the
paired ventral processes have disappeared, and the tail is somewhat
reduced. The second‑instar
larva of Cothonaspis rapae retains the eucoiliform
characters of the first instar, but the segmentation is more distinct,
whereas in Kleidotoma marshalli there is a change to
the polypodeiform. The head of the
latter is very large, exceeding the body segments in width and length, and
the segmentation is exceptionally distinct.
The minute paired processes occur ventrally on the first 10 body
segments. The larva of Figites anthomyiarum (Fig. 128C) is similar to Kleidotoma in all essential
respects though the head is small, the segmentation indistinct, and the tail
situated ventrally and at right angles to the axis of the body. An internal tracheal system is present,
but there are no spiracles. The
second‑instar larva of Charips
sp. (Fig. 126C) is still of the caudate form, though the heavy sclerotization
of the integument is lacking. Each of
the thoracic segments bears a pair of small processes ventrally, and a pair
of large conical structures is present at the posterior ventral margin of the
head. James studied the early instars of
cynipoid larvae and came to the conclusion that the eucoiliform first‑instar
larvae of Eucoila and Cothonaspis are derived from
eggs which hatch in the middle of the protopod stage of embryonic
development, whereas the polypodeiform larvae correspond, as the name
implies, to the polypod phase. The
form of the Figites larva,
with its reduced appendages and distinct segmentation, indicates hatching in
a later embryonic stage than does any of the other species discussed. The Charips
larva, being devoid of appendages, is regarded as preceding or as being a
very early form of the protopod stage.
This view of the stage of development at the time of hatching is borne
out by the occurrence of polypodeiform second‑instar larvae following
the eucoiliform first instar in Figites
and Kleidotoma. Only three instars have been
distinguished in the species studied, with the exception of Ibalia leucospoides, which has four. The third‑instar larva of Ibalia is cylindrical in form with the tail still further
reduced and may be readily recognized by the presence of spiracles on the
second and third thoracic segments. Mature Larvae.--The mature larvae
of the various species differ in only relatively minor characters. That of Ibalia has the integument smooth and shining except in the
pleural areas of the second to eleventh body segments, which bear rounded
"bases" studded with minute spines. The mandibles are tridentate, whereas they ere bidentate in Figites and Charips. There is a somewhat surprising variation
in the number and position of the spiracles.
Ibalia has 10 pairs,
situated on the second and third thoracic and the first eight abdominal
segments; Eucoila keilini and Figites anthomyiarum have nine pairs, on the last two thoracic and
the first seven abdominal segments; Cothonaspis
rapae eight pairs, on the third
thoracic and the first seven abdominal segments; and Charips sp. has only six pairs, on the second and third
thoracic and the first, second, fourth, and sixth abdominal segments. References: Please refer to <biology.ref.htm>, [Additional references may
be found at: MELVYL Library ] |
