Boletín de la AeE

In parasitoid insects, the issue of offspring development depends on female ability to find a suitable host. Specific recognition is often based on responses to olfactory cues, but their origin and nature have been rarely determined (Vet el ai, 1995).

We studied the recognition of odours involved in host location by Lepíopilina boulardi, a larval parasitoid of Drosophila species that develop in fermenting fruits. We investigated the nature and origin of volatile stimuli recognised among complex fruit odours (infested., uninfested fruits), and the impact of learning on this recognition. Oriented responses to tríese odours were observed in a four-armed olfactometer. We tested different banana odours: commercial banana aroma of which fractions are known and mature bananas differently treated (infested, uninfested, wounded, fermented). Our results show that naturely infested bananas induced spontaneous responses. The attraction was not related to larval development. Experiments are currently conducted to determine the role of adult Drosophila, their oviposition activity, and the association of Drosophila and fruit odours. An oviposition experience on an infested banana allows female parasitoids lo memorise the fruit odour itself through associative learning (Kaiser & De Jong, 1995). We discuss the adaptative trait of this process. Otherwise, our data suggest that key compounds are involved in the fruit odour recognition and that olfactive learning has an effect on the sensibility threshold to odours.