Patch Time Allocation by the Parasitoid Diadegma semiclausum (Hymenoptera: Ichneumonidae). III. Effects of Kairomone Sources and Previous Parasitism

Abstract

We investigated the effects of kairomone sources and previous parasitism on the patch-leaving behavior of Diadegma semiclausum, a solitary endoparasitoid of larval Plutella xylostella. Individual female wasps were released onto an experimental plant, and were allowed to freely leave for an alternative host plant placed upwind of the experimental plant in a wind tunnel. In one experiment, the experimental plant was either intact, contained host damage alone, or contained both hosts and host damage. In another experiment, the plant was infested with either unparasitized hosts, hosts parasitized previously by the female herself, or parasitized by Cotesia plutellae, another larval endoparasitoid of P. xylostella. We analyzed the influence of kairomone sources, host types, and within-patch foraging experience on the patch-leaving tendency of D. semiclausum by means of the proportional hazards model. Presence of host damage, and unsuccessful host encounters as a result of host defenses decreased the parasitoids' patch-leaving tendency, while successful oviposition, self-superparasitism, and rejection of parasitized hosts increased their patch-leaving tendency. A conceptual model of the parasitoid's patch-leaving behavior is proposed on the basis of the results of current and previous studies.