Odor from herbivore-damaged plant attracts the parasitoid fly Exorista japonica Townsend (Diptera : Tachinidae)

Abstract

The behavior of female Exorista japonica Townsend (Diptera : Tachinidae) in response to an herbivore-damaged plant was examined in a wind tunnel bioassay. We used the common armyworm, Mythimna ( =Pseudaletia) separata Walker, as a host for this fly and as an herbivore to damage corn plants. Experienced flies conditioned to oviposit on the host/corn plant complex were attracted mostly to the host/plant complex and required a relatively short time to arrive at the plant. Damaged corn plants without host larvae and their frass were also attractive. However, only a few experienced flies were attracted to the undamaged plants. These two responses indicate that the damaged corn plants without the herbivore present emit an attenuated signal odor for female flies. The host larvae per se did not attract the flies. Naive flies had lower responses to the host/plant complex than the oviposition-experienced flies, indicating the importance of oviposition to the host with or without a damaged plant.