Prey identification in the polyphagous digger wasp species Cerceris sabulosa (Hymenoptera: Crabronidae)
Females of the digger wasp Cerceris sabulosa hunt for individuals of specific bee species from the genera Lasioglossum and Halictus (Hymenoptera: Halictidae) as food for their offspring. They locate their prey on flowers in the vegetation and paralyse them by a sting in the anterior thorax. Subsequently, the prey is transported in flight to their burrows containing individual brood cells.
Because of its broad prey spectrum, C.sabulosa is considered a polyphagous predator. However, female wasps must discriminate between potential prey and non-prey. Generally, many insects rely on chemical stimuli for prey recognition. Thereby, some chemical compounds on the cuticle of a prey species can serve as kairomone for predator species. Yet, C. sabulosa, too, relies on chemical cues for prey identification.
In my diploma thesis, I investigate the chemical characteristics of the kairomone used by C. sabulosa females for prey choice and identification. My methods include behavioural assays, gas chromatography coupled with mass spectrometry (GC-MS) analysis of cuticular bouquets and the comparison thereof between prey and non-prey bee species.
Finally, I will test the hypothesis, that all prey species are characterised by a common kairomone. In that case, the generalist C. sabulosa might in reality be a “chemical” specialist.
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