Foraging for Patchily-Distributed Hosts by the Parasitoid, Nemeritis canescens

Abstract

The locomotory responses which influence patch time allocation were investigated for the parasitoid, N. canescens (Grav.). Arrestment in patches was brought about by orthokinetic and klinotactic responses to a host-produced chemical and, indirectly, by oviposition. A series of ovipositions increased patch time in a manner dependent on their rate rather than their absolute number. A behavioral model is developed for the duration of a patch visit at different host densities. The aggregative response predicted is compared with experimental findings. The effect of experience on patch time is investigated. Nemeritis avoids already visited patches. More long-term effects of conditioning on patch time are also suggested. The manner in which Nemeritis forages is compared to that predicted by foraging models, and the nature of the parasitoid foraging process is discussed.