Determination of double bond position and stereochemistry in unsaturated cuticular hydrocarbons of Drosophila species

The cuticular lipids of insects consist of complex mixtures of alkanes, alkenes and more highly unsaturated hydrocarbons, and polar compounds.  Some of these compounds act as contact pheromones and so accurate identification of sex- or species-specific compounds in cuticular extracts is a prerequisite to determining their roles as pheromonal signals. Whereas saturated hydrocarbons can be completely identified by GC-MS alone, GC-MS usually provides no information as to the positions and stereochemistries of double bonds in alkenes. 

Methods for the fractionation of crude cuticular extracts will be described, along with methods used to determine the double bond positions, for the four species Drosophila persimilis, D. pseudoobscura, D. simulans, and D. willisoni .