Absence of odour learning in the stemborer parasitoid Cotesia flavipes

Abstract

Parasitic wasps are commonly found to learn olfactory and visual cues that are associated with successful host location. For many parasitoids the cues that are associated with hosts vary in space and time, and are therefore unpredictable. An ability to learn allows the wasp to concentrate on those cues that will lead it to new hosts most effectively in a particular area. In contrast, parasitoids that forage in a predictable homogeneous environment and/or make only a few foraging decisions do not need to learn and should rely on innate responses to specific cues. The role of learning in host foraging was studied in Cotesia flavipes (Hymenoptera: Braconidae), a parasitoid of stemborer larvae with an ecology where learning is expected to be of low adaptive value. There was no evidence that C. flavipes uses odour learning in host-micro-habitat location. There was no significant effect of the development and emergence environment on the response level or preference towards the odour of infested plants. Neither was there evidence that experience with a particular plant-host complex during foraging influences subsequent foraging decisions in C. flavipes females. The absence of learning in C. flavipeswhich seems an exception among the parasitoids studied, is discussed in relation to its ecology.