Abstract: Aphidius gifuensis is a predominant parasitoid of aphid pests. To study the nature of its olfactory responses is critical to the successful implementation of biological control of aphids. In this paper, electroantennogram (EAG) technique was used to investigate the responses of A. gifuensis to the aphid sex pheromones, alarm pheromones, and host-plant (tobacco) volatiles. The results showed that both male and female A. gifuensis had responses to sex heromone components ［(-)-(1R, 4aS, 7S, 7aR)-nepetalactol and (+)-(4aS, 7S, 7aR)-nepetalactone］, aphid-alarm pheromone ［(E)-β-farnesene］, and tobacco volatiles, but their sensory perception to these semiochemicals was differed. The females were much more sensitive to nepetalactol, nepetalactone, cis-3-hexen-1-ol, (E)-2-hexenal, methyl salicylate, and (±)-linalool, suggesting that the males and females adopted different chemical strategies to host location, and perceived different chemical fingerprint in relation to host in host-finding behavior. The sensory perception of A. gifuensis to different odor components was also differed, e.g., green leaf volatiles (E)-2-hexenal, cis-3-hexen-1-ol and hexanal elicited larger EAG responses than terpenoids, indicating that the parasitoids might use green leaf volatiles as long-range cues in their habitat location.

Key words: Heat hardening, Photochemical quenching coefficient, Non-photochemical quenching coefficient, Brassica olexacea