Olfactory plasticity in Microplitis croceipes is influenced by nutritional status

Parasitoids utilize nectar resources found in nature which impact their longevity and energetic needs. Common sugars found in nectar include fructose, glucose and sucrose. It is likely that without a sugar diet, odor reception in parasitoids may be reduced and this may affect host searching ability. However, little is known about the effect of nutrition on response of parasitic wasps to odor. In this study, we used Microplitis croceipes (Hymenoptera:Braconidae), a larval endoparasitoid of Heliothis virescens, as a model insect to test the hypothesis that nutritional status of parasitic wasps affects their olfactory response. Using electroantennogram bioassays, we tested the responses of female M. croceipes fed sugar solutions of different concentrations (50%, 25%, 10% or 0% by volume sucrose/water) to four odor stimuli commonly found in cotton, including a green leaf volatile (GLV), a constitutive monoterpene, a binary mixture of the GLV and monoterpene, and VOCs obtained from H. virescens-damaged cotton. The ecological consequences and potential field applications of the results are discussed.