Foraging Behaviour and Patch Exploitation by Campoplex dubitator (Hymenoptera: Ichneumonidae), a Parasitoid of Bark-mining Larvae

Abstract

This study examines the foraging behaviour of Campoplex dubitator Horstmann (Hymenoptera: Ichneumonidae), a parasitoid of the highly concealed bark-mining host, Enarmonia formosana Scopoli (Lepidoptera: Tortricidae), and how this foraging behaviour is affected by host density. The ultimate aim was to determine whether foraging behaviour and patch fidelity could explain patterns of parasitism in the field. An ethogram was first constructed to portray C. dubitator behaviour prior to and immediately following host attacks. The pre-attack behavioural sequence was highly structured whereas behavioural transitions became less predictable after a sting event. Females spent more time on patches with higher host densities and host encounters caused a significant reduction in the leaving tendency. The giving up time was only slightly affected by host encounters. Campoplex dubitator did not demonstrate the ability to distinguish between occupied and empty host mines. The results show that C. dubitator forages more efficiently at lower host densities and this behavioural phenomenon may result in the patterns of parasitism observed in the field.