Identification of pupal exuviae of Nasonia vitripennis and Muscidifurax raptorellus parasitoids using cuticular hydrocarbons

Parasitoids are often members of species complexes and are difficult to ide ntify by conventional morphology, although most indigenous parasitoids of m uscoid flies can be identified from adults. Pupal exuviae of the gregarious parasitoids Muscidifurax raptorellus Kogan and Legner and Nasonia vitripen nis (Walker) were dissected from parasitized house fly (Musca domestica L.) puparia. Their hydrocarbons were extracted, isolated, and analyzed via col umn and gas chromatography, as were those of adult parasitoids. Quantificat ion of 7-methylhentriacontane and 3,7,15-trimethylpentatriacontane allowed calculation of peak ratios of these two methyl-branched components that sho wed statistically significant differences between the species. Since the pr ofiles were dramatically different, a confident identification resulted. An alysis of adult parasitoids or the mummified host remains from parasitized host puparia also revealed distinctive hydrocarbon profiles between species , and the same peak ratios were definitive for each species. Since there ar e no morphological keys for pupal life stages, hydrocarbon profiles provide a simple and reliable method to identify parasitoids from parasitized host puparia, before or after the adult parasitoids have left the host. In addi tion, the parasitoid species found in parasitized pupae can be determined f rom analysis of the empty puparium or even the mummy itself.