Behavioral Response of the Parasitoid Cardiochiles nigriceps to Kairomones

Abstract

The response of the parasitoid Cardiochiles nigriceps (Hymenoptera: Braconidae) to the contact chemical of its host, Heliothis virescens (Lepidoptera: Noctuidae) is investigated in the following study. In response to an encounter with the host kairomone, C. nigriceps exhibits a kinetic response within the confines of the chemical patch involving increased turning and increased speed over unit time. When the parasitoid encountered a patch edge, it exhibited a klinotactic response which directed the parasitoid back to the interier of the patch. This orientation occurs because of the insect turning an average angle of 143° relative to its orientation at the time of the stimulus. Such an action greatly increases the time spent by C. nigriceps on a patch. Oviposition has the effect of significantly reducing the time spent by C. nigriceps on a patch. The nature of the distribution of H. virescens may be the cause for the observed reduction in patch time-as a result of oviposition. Experience of the parasitoid also appears to be a factor in the host location process.