Use of Natural Enemy Attractant (Synomone) and Associative Learning in Biological Control

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The ability of Cotesia kariyai females to learn plant volatiles associated with an oviposition experience was investigated. First, we observed the wasps' oviposition behavior when encountering a host. Most naive wasps showed oviposition behavior at the first encounter. Immediately after the first oviposition, only 30% of the wasps showed a second oviposition response after several encounters with the host. Six hours after the first oviposition, ca.80% of the wasps showed a second oviposition response at the first contact. Second, the response of wasps to plant volatiles was investigated in a wind tunnel. Within a few hours after the oviposition experience, the response of females to volatiles was not significantly different from that of naive females. However, eight hours after the first oviposition, females showed significantly higher responses to the volatiles than the naive females. The effect of oviposition experience on the learning response of C.kariyai is discussed.Effect of leaf age on the flight response of a parasitic wasp, Cotesia kariyai, to a plant-herbivore complex was studied in a wind tunnel. Both young and old leaves infested with host larvae (common armyworms : Mythimna separata) attracted more wasps than their respective uninfested leaves. Preference of the wasps to uninfested young leaves vs.uninfested old leaves was not significantly different in choice experiments. However, when young infested leaves were compared against old infested leaves in choice experiments, the wasps showed significant preference to the former. n the single stand experiments, % landing response to young infested leaves was not significantly different from the old infested leaves. The fact that attractiveness of infested corn leaves to wasps differs according to leaf age suggests differential allocation of induced indirect defense in the corn plant.