The venom of Megarhyssa (Hymenoptera: Ichneumonidae): Putative proteins and possible functions

Species of the genus Megarhyssa are ectoparasitic idiobionts that parasitize the larvae of siricid wasps. Siricid larvae bore deep into tree trunks and parasitizing them necessitates the penetration of wood, a feat achieved by the gracile ovipositor of the parasitoid in a matter of minutes. We hypothesize that the venomous secretions of these wasps not only alter host physiology but also contain enzymes which rapidly degrade wood. Using a joint transcriptomic-proteomic approach, proteins in the venom, and the genes which code for them, are being identified.

RNA isolated from the abdomen of female wasps was sequenced and the resulting contigs were transformed into a database against which known hymenopteran venom proteins and wood degrading enzymes were queried. In this bioinformatic study more than 150 hymenopteran venom proteins showed significant sequence similarity to Megarhyssa transcripts. The enzymes laccase and glycosyl hydrolase, which are associated with wood degradation, also returned significant hits from the wasp transcriptome.

Separation of venom proteins using gel electrophoresis indicates that the composition of the venom is variable among species and the results of a mass spectrometry analysis of each venom sample will be discussed.