Antagonistic selective pressures in the evolution of species specific cuticular hydrocarbon profiles in solitary Hymenoptera
Apart from hydroregulation, cuticular hydrocarbons (CHC) can serve several derived functions in insects. Such functions are for example communication in social insects and kairomone use by predators and parasitoids. The resulting selective pressures could act stabilizing (in the case of intraspecific communication), diverging (kairomone use) or shifting (climatic factors) on the composition of CHC profiles.
In a comparative study, I aim to evaluate the interactions of different selective pressures in digger wasps of the genus Cerceris. If we hypothesise no selective pressure on the CHC profiles, the similarity of their composition should correlate with the relatedness of the species. Yet, unique sets of selective pressures in groups of species due to ecological, behavioural and abiotic factors should lead to CHC compositions contradicting the former basic assumption.
Selective pressures under investigation:
Prey specificity:
Female Philanthinae wasps hunt specifically either Hymenoptera or Coleoptera to provide food for their progeny. Hymenoptera-hunting species apply a glandular secretion (with the same composition as their CHCs) to prey items stored in brood cells. Coleoptera hunters do not process prey in this way.
Parasitoid pressure:
Evading the chemical mimicry used by specific Chrysididae parasitoids could alter cuticular hydrocarbon profiles.
Biogeography:
Climatic factors might influence the optimal composition of cuticular hydrocarbons with regard to the physical properties.
Sociality:
Cerceris rubida, the only social species of the Philanthinae in Europe, can distinguish nestmates from non-nestmates.
Funding: DFG SCHM2645/1-1 |
