Species-specific mate discrimination based on cuticular hydrocarbon differences in parasitoid waps of the family Pteromalidae (Hymenoptera: Chalcidoidea)
The Pteromalid jewel wasps are a species-rich and diverse Hymenopteran family whose larval stage is characterized by parasitizing the pupae of various Diptera. Many Pteromalid species occur in close sympatry, with high potential for interspecific matings. Postzygotic reproductive isolation has been well studied in this group, where it is mostly mediated through intracellular infections with species-specific Wolbachia bacteria, whose effects range from cytoplasmic incompatibility to induced parthenogenesis. These infections mostly impair the generation of viable and/or fertile hybrids in zones of sympatry, imposing considerable cost on interspecific matings. Therefore, we assume selection pressure on the development of prezygotic hybridization barriers to counteract the fitness losses originating from copulations with heterospecific mates.
Cuticular hydrocarbons (CHC) have already been shown to be involved in prezygotic reproductive isolation in various insect taxa, and we attempt to investigate their potential as species-specific sexual cues in several representatives of the Pteromalidae.
In Nasonia, the best studied Pteromalid genus, it has been shown that female CHC can function as sex pheromones in triggering male courtship. In some Nasonia species, males can discriminate heterospecific from conspecific female CHC. In my diploma thesis, I will focus on two main aspects. First I will investigate whether these findings can be extrapolated to more distantly related genera of the Pteromalidae, comparing male mate discriminatory behaviour across representatives of the genera Trichomalopsis, Muscidifurax and Nasonia.
Second, I will analyse female and male Pteromalid CHC-profiles utilizing gas chromatography coupled with mass spectrometry (GC-MS) and compare these profiles across the genera to screen for genera-specific differences and to check whether these differences reflect the phylogeny of the Pteromalidae.
|
