Drosophila Free-flight Odour Tracking is Altered in a Sex-specific Manner by Preimaginal Sensory Exposure

Abstract In insects such as Drosophila melanogaster, flight guidance is based upon converging sensory information provided by several modalities including chemoperception. Drosophila flies are particularly attracted by complex odours combining volatile molecules from yeast, pheromones and microbe-metabolized food. Based on a recent study revealing that adult male courtship behaviour can be affected by early preimaginal exposure to maternally-transmitted egg factors, we wondered whether a similar exposure could affect free-flight odour tracking in flies of both sexes? Our main experiment consisted to test, in a wind tunnel, flies differently conditioned during preimaginal development. Each fly was presented to a dual choice of food labelled by groups of D. melanogaster or D. simulans flies of each sex. The combined effect of food with the cis-vaccenyl acetate pheromone (cVA), involved in aggregation behaviour, was also measured. In parallel, using the head-space method, we determined the "odorant" identity of the different labelled food tested. We also measured the antennal electrophysiological response to cVA in females and males resulting of the different preimaginal conditioning procedures. Our data indicate that flies differently modulated their flight response (take off, flight duration, food landing and preference), according to sex, conditioning and food choice. Our head-space analysis revealed that many food-derived volatile molecules diverged between sexes and species. Antennal responses to cVA showed a clear sex specific variation for conditioned flies, but not for control flies. In summary, our study indicates that preimaginal conditioning can affect Drosophila free flight behaviour in a sex specific manner.