Oviposition Behavior of the Predatory Midge Aphidoletes aphidimyza in Response to Aphid Patch Quality

Female Aphidoletes aphidimyza confronts serious challenges from both aphid prey and conspecifics. These challenges constitute strong selective pressures on the predatory midge to have an adaptive oviposition strategy. We did laboratory experiments to investigate clutch size of A. aphidimyza in response to the aphid Rhopalosiphum padi (density and age) and the presence of conspecific eggs (density) and larvae (age) in aphid colonies. The results of our study show that A. aphidimyza female adjusts its foraging effort by assessing the quality of prey patches. The number of eggs laid increased in response to aphid density. However, patches consisting of older aphids received fewer eggs. The number of eggs laid decreased in response to the presence of conspecific eggs, and in response to the presence of 2-day old conspecific larvae. Our study reveals deterrent effects on A. aphidimyza oviposition decisions on clutch size in response to older aphids and the presence of more conspecific eggs and older larvae.