Learning and the role of host‐specific volatiles during in‐flight host‐finding in the specialist parasitoid Microplitis croceipes

The effect of antennal contact with host‐related stimuli on the subsequent flight response to host‐specific volatiles was examined in the specialist parasitoid, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae). In a choice test between two species of caterpillars feeding on cowpea, free‐flying female M.croceipes lacking prior contact with host cues landed more often on sources of odour from its host, Heliothis tea (Boddie), than from non‐host Spodoptera frugiperda (Smith). After female parasitoids contacted host cues with their antennae, more landings on sources containing hosts were observed only when caterpillars used in the pre‐flight treatment and in the odour sources fed on the same plant species. The degree to which host‐experienced wasps landed more often on hosts as compared with non‐hosts varied with host‐instar and plant species. The role of learning in host finding in specialist parasitoids is discussed.