Ontogeny of Drosophila melanogaster female sex-appeal and cuticular hydrocarbons

The chemical communication system in Drosophila melanogaster Meigen, 1830 plays a major role in courtship and consists of the male-specific cis-Vaccenyl acetate and sex-specific contact pheromones, cuticular hydrocarbons (CHC), which build up during ontogeny (first 4 days). They replace longer CHCs, common to both sexes and present only after the imaginal eclosion. A detailed quantitative description of the evolution of cuticular unsaturated hydrocarbons with age is presented here for males and females of different D. melanogaster strains, which have been bred in well controlled environments. Monoenes appear in both sexes at around 12 h, before female dienes. The present paper argues that this is likely linked to the switching on of a new set of genes. Ecdysone, which is more abundant in females than in males during this critical period, might control this switch. Parallel behavioral studies show that whereas female of all ages trigger early mature male courtship steps like wing vibration, only females older than 1 day trigger late courtship steps like attempted copulation. This supports the hypothesis that late male courtship steps might be triggered by the CHCs, which build up after this age, especially female-specific (Z,Z)-7,11- and (Z,Z)-5,9-dienes