Body Odor and Sex: Do Cuticular Hydrocarbons Facilitate Sexual Attraction in the Small Hairy Maggot Blowfly?

Cuticular hydrocarbons (CHCs) play an important role as contact pheromones in insects, particularly in flies. However, for many fly taxa our understanding of the importance of CHCs in sexual communication is limited. Within the family Calliphoridae (blowflies), sex-specific differences in CHCs have been reported for several species, but there is no evidence that CHCs facilitate sexual behavior. In order to elucidate the function of CHCs in Calliphoridae, studies combining behavioral and chemical analyses are required. The present study used gas chromatography/mass spectrometry, along with behavioral assays, to assess whether CHCs facilitate sexual attraction in the small hairy maggot blowfly, Chrysomya varipes. The specific aims were to: 1) determine if CHCs differ between the sexes and 2) assess whether flies exhibit positive chemotaxis to CHCs of the opposite sex. Fifty-two hydrocarbons common to both sexes were identified, and quantitative differences for numerous CHCs were observed between the sexes. However, behavioral assays provided no evidence that flies were attracted to CHCs of the opposite sex, challenging the hypothesis that CHCs facilitate sexual attraction in Ch. varipes. In contrast to other blowflies, Ch. varipes males invest heavily in courtship displays and ornamentation, so we speculate that visual communication in this species may have relaxed sexual selection for chemical communication. More broadly, our findings support suggestions that CHCs may not always facilitate insect sexual communication.