Egg laying site preferences in Pterostichus melanarius Illiger (Coleoptera: Carabidae)

In the case of ground beetles, the number of studies investigating the effects plant-related structure and microclimate on the selection of egg laying sites is very limited. The egg laying site preference of Pterostichus melanarius, an important carabid beetle in agricultural fields, was studied under laboratory conditions. The effects of wet/dry substrate, light/shadow and structured/unstructured environment on the number of eggs laid were investigated, as well as the influence of the presence of barley and Brussels sprout plants. We found that there was a strong influence of plant structure and microclimate on the selection of egg laying sites. Results showed a higher numbers of eggs laid in barley compared to Brussels sprouts. These results were supported by a significant preference for moist, shadowed, structurally complex environments as egg laying sites. Results indicate that vegetation characteristics in themselves may influence egg laying site preferences, beside the availability of prey for the adults and larvae, in the different plant systems.