Cuticular hydrocarbons of Gonipterus weevils: are there species differences?

Gonipterus weevils have been a taxonomic challenge for many years, with implications on our understanding of invasive species, host plant relationships and natural enemies. We assessed cuticular hydrocarbon (CHC) analysis as a tool for discrimination of some of the many species of Gonipterus occurring in Australia. Weevils were collected across several localities and kept under identical conditions prior to a whole-body wash for extraction of CHCs in hexane. Weevil identifications were confirmed using morphology and molecular tools. CHC extracts were analyzed by gas chromatography–mass spectrometry (GC–MS) and the relative peak areas in profiles were compared; compounds were identified according to MS fragmentation and retention indices. CHC profiles of the seven species of Gonipterus analyzed differed from each other, and from another weevil genus (Oxyops), used as an outgroup. The compounds that contributed most to species differences were alkanes, alkenes and methyl branched alkanes. Within some species, locality of collection affected CHC profiles. Our study presents CHC analysis as a promising tool for distinction of Gonipterus species.