Chemical ecology: migration and tritrophic interactions

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The seasonal migration of the monarch butterfly has been well documented yet we still do not understand how the monarchs, born in North America, locate the specific overwintering sites, used year after year in Mexico. We will carry out experiments to test the hypothesis that compounds left by previous generations of butterflies accumulate in the waxes of host trees serve as cues for immigrants, and that these are based on compounds acquired from plants through larval and adult feeding. If true, this will not only answer one of important unanswered questions related to this amazing natural phenomenon, but also provide a potential tool for the conservation of the species. The armyworm is a seasonal migrant cereal pest and we have been using this species as a model system to study moth migration. We are extending our studies of the physiology under lying migratory behavior in the laboratory into the field. The propsed research will contribute to our understanding of eco-physiology in migrant moths, including tradeoffs between migratory flight and future reproduction, and determine if a foraging gene plays a role in migration. It has been well documented that plants emit volatiles following attack by a herbivore and that these are involved in the up-regulation of defenses. Furthermore, natural enemies of herbivores use these volatiles as foraging cues. However, most of the work has been carried out under a limited range of ecological conditions and we have no real understanding of the how important these cues are under variable ecological conditions. Using the unique facilities in the Biotron Climate Change Research Center at UWO we will examine how an array of different climatic conditions affect the up-regulation of plant defenses as the responses of parasitoids to the resulting volatiles. The results obtained will help understand how climate change will affect the induction of plant defenses, help determine to what extent volatiles from defoliated plants serve as foraging cues for beneficial insects and clarify whether there really is any potential for these compounds in integrated pest management programs.