Selective information use in parasitoid wasps

Abstract

Abstract Foraging animals frequently have to decide where to search, what host or prey to accept, and when to leave a patch. To achieve optimal patch exploitation rates, foragers can base their decisions on information about the quality of the current patch and on an estimate of the quality of the entire habitat. The latter has rarely been studied to date. We have analysed the patch-leaving behaviour of the parasitic wasp Asobara tabida Nees (Hymenoptera: Braconidae), a solitary parasitoid of Drosophila larvae, as a function of previous experience. Females were confronted with patches containing different numbers of larvae, which were either unparasitised, or parasitised by a conspecific or larvae of different host species. Our results show that females of A. tabida were able to recognise the different qualities of the patches that we offered but that they used information about host density, host species or parasitism status of the host to different degrees during subsequent patch visits. Encounters with an unsuitable host species had a great impact on future patch-leaving decisions while the effect of host density was relatively weak. If wasps had encountered previously parasitised hosts no response could be detected during subsequent visits. We argue that the various information sources provided are of different value for the searching female and that this might explain the observed pattern of selective information use.