Data from: Analysing small insect glands with UV-LDI MS: high-resolution analysis reveals the chemical composition and use of the osmeterium secretion in Themira superba (Sepsidae: Diptera)

For many insect species pheromones are important communication tools, but chemical analysis and experimental study are technically challenging because they require the detection and handling of complex chemicals in small quantities. Traditional mass spectrometry has the drawback that most methods require whole-body extractions from one to several hundred individuals with the consequence that intra- and inter-individual differences cannot be detected. Here we used the recently introduced UV-LDI MS (Ultraviolet Laser Desorption/Ionization Mass Spectrometry) to profile the “osmeterium” of the sepsid fly Themira superba that is located on the edge of the hind-tibia of males. Based on analyses of individual legs, we established that the gland produced a secretion that consisted of oxygenated hydrocarbons and putative isoprenoids. The secretion was first detected 24 hours after eclosion and we used UV-LDI MS to demonstrate that it was transferred to the wings of females during mating. We then tested whether the secretion had an anti-aphrodisiac function, but experimental transfer of the secretion to virgin females did not affect mating success or copulation duration. Throughout the study, UV-LDI MS proved invaluable, because it allowed for tracking the natural and experimental transfer of small quantities of pheromones to specific body parts of small flies.