GC-EAD responses of Microplitis croceipes (Hymenoptera: Braconidae) to headspace volatiles from cotton plants damaged by host (Heliothis virescens) and non-host (Spodoptera exigua) caterpillars

Parasitic wasps are known to utilize as host location cues volatiles released by plants in response to damage by herbivorous insects. Previous research has documented qualitative and quantitative differences in the volatile chemical profiles of cotton plants damaged by different species of caterpillars, which may play a major role in mediating host specificity by specialist parasitoids. In this study, we compared GC-EAD (coupled gas chromatography electroantennogram detection) responses of the specialist parasitoid, Microplitis croceipes to headspace volatiles of cotton plants damaged by Heliothis virescens (a host species) versus Spodoptera exigua (a non-host species). In general, M. croceipes females respond to similar GC-EAD peaks of volatiles induced by host and non-host caterpillars. However, a few peaks which occurred only in the headspace of cotton damaged by H. virescens also elicited GC-EAD response in M. croceipes. Identification of these host-specific GC-EAD peaks may support our ongoing research on mechanisms of olfaction in this parasitoid.