Flight response of parasitoids toward plant-herbivore complexes: A comparative study of two parasitoid-herbivore systems on cabbage plants

We observed the flight response of Cotesia plutellae and C. glomerata, which respectively parasitize Plutella xylostella and Pieris rapae, to crucifer plants. C. plutellae preferred the cabbage and Japanese radish plants infested by the hosts to uninfested, artificially damaged and nonhost (P. rapae)-infested plants. C. glomerata preferred host-infested cabbage plants to uninfested plants. However, C. glomerata showed an equal preference for host-infested plants and nonhost (P. xylostella)-infested or artificially damaged plants. In a comparison between plants infested by both herbivore species and those infested by the respective host larvae, C. plutellae preferred the host-infested plants, whereas C. glomerata preferred the plants infested by both species. These results indicate that (1) C. plutellae shows a specific response toward the host-plant complex, whereas C. glomerata does not, and (2) the presence of the nonhost affects the specificity of the response of the wasps toward the host-plant complex.