Sari Anschütz

• For most terrestrial species, the detection and decoding of a special set of olfactory signals, known as pheromones, are crucial for communication, reproduction and survival. These chemosensory cues are typically secreted by specialized glands or tissues and elicit stereotyped behavioural or physiological responses such as attraction or avoidance in subjects of the same species. In this study, developing Drosophila melanogaster larvae were investigated, with a focus on behaviour-determining pheromone compositions from a wild-type strain and transgenic lines lilli189Y-Gal4 > UAS-CsChrimson and lilli189Y-Gal4 > UAS-GtACR1. While former analysis of pheromone excretion in Drosophila was mainly performed in adult flies, this work presents a novel method to examine secreted pheromones in the larval stage using gas chromatography and mass spectroscopy (GC/MS). For CS (wild-type) larvae, ten cuticular hydrocarbons were identified, including several alkanoic acids and the pheromones (Z)-9-tricosene, tetracosane, pentacos-1-ene, 2-methylhexacosane and 7,11-heptacosadiene. Adult flies of the same strain contrarily showed much higher concentrations, as well as a considerably different pheromone profile and a greater diversity of pheromones. Examination of the transgenic larvae showed a very similar profile of cuticular CHs, including one novel compound, erucic acid, which was found in addition to those already detected in the wild-type. It was further revealed that, while the differences in the unstimulated state of the genotypes tested were consistently significant, stimulation of the lilli189Y-Gal4 > UAS-CsChrimson and lilli189Y-Gal4 > UAS-GtACR2 larvae did not cause any significant changes in their profile of cuticular hydrocarbons.