Do female coleopteran parasitoids enhance their reproductive success by selecting high‐quality oviposition sites?

Summary1 Female parasitoids that lay their eggs away from potential host insects are supposed to have only a minor influence on the fitness of their own progeny, as they do not select and evaluate directly the quality of hosts for their offspring. Aleochara bilineata Gyll. (Coleoptera: Staphylinidae) females oviposit near to cabbage plants infested by larvae of Delia radicum L. (Diptera: Anthomyiidae). Once the mobile A. bilineata larva emerges from the egg, it must then search the soil to find and select a suitable fly pupa. The beetle larvae have a limited time to found pupae and can only parasitize one host pupa during their lifetime. Moreover, because A. bilineata is a solitary parasitoid whether or not the host pupa is parasitized, has a strong influence on the successful development of the beetle larva. 2 We studied the oviposition behaviour of A. bilineata females in laboratory experiments in which females could choose between a range of several oviposition sites. 3 Our results reveal that A. bilineata females, like hymenopteran parasitoid females, show an adaptive oviposition behaviour in response to the quality of the oviposition site. The female beetles adapt their oviposition decisions and their clutch size based on information associated with the presence of a host. Furthermore, our results reveal that the Aleochara females can discriminate between specific cues related to the stage and parasitization status of the host. Such behaviours may greatly enhance the parasitization success of the larvae, and thereby female fitness.