File: <helor1.ima.htm> [For educational purposes only] Terminology Glossary <Principal Natural
Enemy Groups > <Citations> |
Immature Stages
of Heloridae
Immature stages of Heloridae were discussed in detail by Clausen
(1940), as follows: The early stages of Heloridae were known only in the case of Helorus paradixus, and consequently no general description can be
given for the family. It is
noteworthy, however, that the instars here described bear a striking
similarity to those of Phaenoserphus
and Paracodrus of the
Proctotrupidae and of Collyria
of the Braconidae. The newly laid egg of H.
paradoxus (Fig. 122A) is
white, oblong in form, and slightly wider at the anterior end and bears a
minute conical micropyle. The first‑instar
larva (Fig. 122C) is elongated and polypodeiform, with 13 body segments, of
which the posterior ones are indistinctly indicated. The head is heavily sclerotized and bears
a peculiar oral "sac," which is structureless and transparent. Within this sac are the mandibles, which
are large and heavily sclerotized.
Each abdominal segment except the last bears a pair of large fleshy
processes ventrally. Those of the
caudal segments are of decreasing size.
The last segment is drawn out into a short, ventrally curved tail. The respiratory system is vestigial and
consists only of two short lateral trunks with a small number of simple
branches but no commissures. The second‑instar larva (Fig. 122D) is unlike the preceding
one; for it lacks the heavily sclerotized head capsule and the fleshy paired
ventral processes, and the tail is greatly reduced. The mandibles appear to be entirely lacking. There are no cuticular spines or
setae. The respiratory system
comprises well‑developed lateral trunks extending the length of the
body, with spiracular spurs in many segments and extensive dorsal and ventral
branches, but no commissures or spiracles. Please CLICK on picture to view details: The mature third‑instar larva (Fig. 122E) is robust in form
and is distinguished principally by the markings of the head. There is a peculiar dark‑brown
melanized band (Fig. 122H) encircling the lateral posterior margins, which
appears gradually and is apparently oxidative in nature. The mandibles are widely spaced and
vestigial. Eight pairs of spiracles
are present, these being situated near the anterior margins of the second
and third thoracic and the first six abdominal segments. Blind spiracular stalks occur in the
seventh and eighth abdominal segments.
The posterior commissure is still absent in this instar. In the second and third instars, there is a peculiar modification
in the mid‑gut, apparently not noted heretofore in parasitic larvae,
consisting of a series of five membranous sacs, each within the next largest
one, and connected by a definite cellular neck to the juncture of the fore-
and mid-gut (Fig. 123). They are
termed "peritrophic sacs" by Clancy and they increase greatly in
size as larval development progresses.
It has been determined that these sacs serve as a form of filter to
extract the excess moisture from the meconial mass, and the solid materials
are then retained in the body until the emergence of the adult (Clausen
1940). References: Please refer to <biology.ref.htm>,
[Additional references may be
found at: MELVYL Library ] |