Abstract: Jasmonic acid (JA) is a group of important signal molecules carrying information about injury in plants. Application of exogenous jasmonic acid to plants can induce them to produce various defense responses, such as changes in composition of volatiles, which in turn affect phytophagous insects and their natural enemies. We report here the effects of Chinese cabbage and common cabbage volatiles induced by exogenous jasmonic acid on the host searching and selection behavior of a hymenopteran parasitoid Cotesia plutellae. For both Chinese cabbage and common cabbage JA-treated plants produced volatiles more attractive to adult females than untreated plants. Compared with untreated plants, the number of Plutella xylostella larvae parasitized by C. plutellae on JA-treated plants of Chinese cabbage was significantly higher. These results demonstrate that application of exogenous jasmonic acid on Chinese cabbage and common cabbage can make these plants more attractive to the parasitoid, and thereby promote its efficiency of host foraging.

Key words: Exogenous jasmonic acid, Chinese cabbage, common cabbage; Cotesia plutellae; host foraging, oviposition preference