Habitat Selection by the Introduced Biological Control Agent Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) and Implications for Nontarget Effects
2006
Yong, T.H. | Hoffmann, M.P.
Trichogrammatid wasps are used widely as biocontrol agents against a variety of lepidopteran pests. However, the broad physiological host range of most Trichogramma species raises concerns about the potential impact of released wasps on nontarget Lepidoptera. If wasps exhibit a preference for agricultural over nonagricultural habitats, this could lessen the risk for many nontarget species that occur primarily in natural habitats. In this study, we examined the habitat selection behavior of Trichogramma ostriniae Pang and Chen, an Asian species that has shown considerable promise in the United States as a biological control agent against the European corn borer, Ostrinia nubilalis Hübner (Lepidoptera: Crambidae). On two different farms, we released wasps in a border area between corn (Zea mays L.) and natural forest, at locations equidistant to the two habitats. We monitored wasp movement for 4 wk using sticky cards placed up to 30 m inside each habitat. The results showed that T. ostriniae wasps have no inherent avoidance of entering forest habitat. Overall, however, corn habitat was more attractive to the wasps than forest habitat. The relative attractiveness of corn versus forest habitat also increased over time. We discuss our results on T. ostriniae habitat selection behavior within the context of information on T. ostriniae physiological host range and searching efficiency within different habitats and address the implications for risk to nontarget forest Lepidoptera.
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