Plasticity of response to host plant volatiles in two parasitic wasp species

Olfactory plasticity has been documented as an important characteristic involved in foraging behavior of many insects. Natural enemies, such as parasitoids, are known to use volatile organic compounds (VOCs) released by herbivore damaged plants to locate their hosts. The parasitoid Microplitis croceipes (Hymenoptera: Braconidae) utilizes VOCs to locate hosts for oviposition. We investigated the effect of physiological state on the behavioral and electrophysiological responses of M. croceipes to VOCs. It is hypothesized that parasitoid olfactory response is plastic and dependent on physiological states such as age and mating status. Y-tube olfactometer bioassays and electroantennogram (EAG) were used to test the effects of age and mating status on olfactory responses of M. croceipes to a single VOC and Heliothis virescens-damaged cotton. Female parasitoids tested were either mated or unmated and separated into age groups of 1-3, 4-6, 7-9 and 10-12 day old.