The remarkable biology of a new species of Gelis Thunberg, 1827 (Ichneumonidae, Phygadeuontinae), a solitary endoparasitoid of fresh eggs of Timarcha (Coleoptera, Chrysomelidae)

By

Shaw, Mark
Kan, Pieter
Kan, Pieter
Schwarz, Martin

Type

Article

Date of Publication

2021

Original Publication

Journal of Hymenoptera research

Volume

82

Pages

161--186

Subjects

Cocoon , Diapause , Egg , first instar larva , France , Gelis timarchae , oviposition , plastic phenology

Contributed by

Pensoft Publishers

Language

English

Published by

Washington, D.C International Society of Hymenopterists

Identifiers

DOI: https://doi.org/10.3897/jhr.82.64657

 

Abstract

A new species, Gelis timarchae Schwarz, Shaw & Kan, is figured and described from specimens reared as a solitary endoparasitoid of fresh eggs of Timarcha nicaeensis in the south of France. Oviposition behaviour of the adult parasitoid, directly into the host cytoplasm, is described and links to videos are given. This appears to be the first record of any ichneumonid developing as an endoparasitoid of an insect egg, and it is a major departure from hitherto known ectoparasitoid (or spiders’ egg-predation) behaviour in the genus Gelis. Fluid from the host egg issuing from the base of the parasitoid’s ovipositor early in the oviposition process is interpreted as a necessary reduction of hydrostatic pressure before the parasitoid egg can be forced down the ovipositor. The egg and first instar larva are figured; the latter is caudate, with the caudal appendage very unusual in being bifurcate. The complex phenology and diapause of the parasitoid were investigated partly experimentally; it is broadly bivoltine with a prepupal diapause in summer, but extra generations and prolonged diapause were both also seen.