Is host selection influenced by natal and adult experience in the parasitoid Necremnus tutae (Hymenoptera: Eulophidae)?

Abstract

Host selection in parasitoids can be influenced by learning cues obtained during natal and/or adult experience. We investigated the effects of natal and adult host experience on host selection by the indigenous parasitoid Necremnus tutae (Hymenoptera: Eulophidae), with an exotic host, the invasive tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), and a native host, Cosmopterix pulchrimella (Lepidoptera: Cosmopterigidae). Colonies of the parasitoid N. tutae were reared on the exotic host T. absoluta and the native host C. pulchrimella, infesting tomato and upright pellitory plants, respectively. Six groups were obtained based on their rearing histories (T. absoluta or C. pulchrimella larvae) and adult experience (no exposure to host larvae or oviposition experience on the two host species). Parasitoid females of the six groups were tested for behavioural responses to the two host–plant complexes (HPCs) in Y-tube olfactometer assays and in two-choice assays in test arenas. The results suggest that host experience during both natal and adult life may affect the HPC preference of this parasitoid species. In particular, adult experience proved to influence the host preference in both olfactometer and two-choice assays. By contrast, natal experience showed a significant influence on host choice only in naive parasitoid females in the olfactometer bioassays. In general, the exotic host T. absoluta–tomato complex was the odour source preferred by the parasitoid N. tutae. The role of natal and adult experience in host-shifting dynamics and how these experiences can combine in adapting mechanisms to a new exotic insect of a generalist parasitoid species are also discussed.