Learning used as a strategy for host stage location in an endophytic host‐parasitoid system

Abstract

AbstractThe relationship between host stage selection and foraging behaviour of Pholetesor bicolor Nees (Hymenoptera: Braconidae), a larval parasitoid of Phyllonorycter spp. (Lepidoptera: Gracillariidae), was investigated under laboratory conditions. The endophytic host develops through two larval stages with different feeding habits, accordingly named sap‐ and tissue‐feeders. The parasitoid was able to find and parasitise both larval stages, even though it is most successful in parasitising the sap‐feeder stage. The influence of experience in the parasitoid's searching behaviour was observed in a choice bioassay. Searching activity increased when either contact experience with the sap‐ or the tissue‐feeder host was given. Furthermore, the ability of the parasitoid to locate a sap‐ or a tissue‐feeder infested plant was influenced by the type of experience given prior to the bioassay. Naive females were less active, and were observed with equal frequency on sap‐feeder, tissue‐feeder and non‐infested plants. In contrast, females that were given previous contact experience with sap‐feeders (i.e., the host stage which provided the most successful parasitism) were observed foraging more often on plants infested by the sap‐feeders, than on those infested by tissue‐feeders or on non‐infested plants. Experience with a tissue‐feeder host had no detectable effect on host stage location and only enhanced P. bicolor's foraging activity. The advantages of learning in this tritrophic system are discussed.