The effects of associative learning of plant chemicals on host-searching behavior in Ascogaster reticulata Watanabe, an egg-larval parasitoid of the smaller tea tortrix, Adoxophyes honmai Yasuda, were investigated. Learned responses of conditioned and non-conditioned plant species were examined by a two-choice assay. Before the two-choice assays, females were given a rewarding oviposition experience or unrewarding experience on a leaf disc or leaf extract of either tea, camellia, sasanqua, bayberry, chinquapin, rose, Japanese cedar, fern pine, mulberry and corn. Following the experience, females were tested in a choice test between tea leaf and an alternative plant leaf. The results of the two-choice assays with leaf square discs were similar to tests using leaf extracts. Females that were conditioned with tea leaf showed a significant preference for tea leaf over the alternative plant species, except for leaves of the genus Camellia (camellia and sasanqua). Wasps conditioned with the other nine plant leaves only showed a significant preference for bayberry, mulberry, fern pine and corn. Females that had rewarding and unrewarding experiences were able to distinguish between tea and camellia. These results suggest that A. reticulata females are able to distinguish different plant species except for closely related species and some plant species; however, combinations with rewarding and unrewarding experiences enabled females to discriminate closely related species.
