Sex-specific elicitor from Adoxophyes honmai (Lepidoptera: Tortricidae) induces tea leaf to arrest the egg–larval parasitoid Ascogaster reticulata (Hymenoptera: Braconidae)

Ascogaster reticulata Watanabe (Hymenoptera: Braconidae) is an egg–larval endoparasitoid wasp of several tortricid species, including Adoxophyes honmai Yasuda (Lepidoptera: Tortricidae). Little information is available on how this parasitoid can find A. honmai eggs using cues produced by tea plants in tritrophic interactions. Therefore, we focused on parasitoid responses to egg-laden tea leaves to determine the source of elicitors of these responses. In two-choice contact bioassays, female wasps spent longer on egg-laden leaves or leaves treated with host female reproductive system homogenates than on intact or untreated leaves at 24 or 48 h after initiating treatment. When tea leaves were treated with diluted host mated-female reproductive system homogenates, wasp residence time was reduced compared with the residence time spent on tea leaves treated with the original concentration of homogenates (reproductive system + 10 μl Ringer’s solution). Moreover, the leaves treated with virgin female reproductive system homogenates also arrested wasps. We conclude that egg deposition by A. honmai induces changes in tea leaves that affect parasitoid behavior. The elicitor of these changes likely occurs in the reproductive system of female moths.