DISSERTATION RESEARCH: Chemical Mediation of Multi-trophic Interactions: A Test of the Tri-trophic Interactions Hypothesis

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Insects can be tremendously beneficial, enormously harmful, critical to sustain important ecosystem services, and key to the success of agricultural crops. This project will strengthen the fundamental understanding of insect dynamics by examining the simultaneous effects of resources, competitors, and enemies on insect dynamics. Application of the results will similarly improve agriculture and management of biodiversity. Natural populations are controlled by a complex of factors that include the amount and quality of food available, competition with other individuals for these resources, and the number and kinds of natural enemies present. However, most studies of the dynamics of insect populations, for example, address only pairs of these complex interactions. This project relies on a newly developed hypothesis, the Tri-Trophic Interactions Hypothesis, to test the simultaneous effects of food quality, diet breadth, and natural enemies on the regulation and coexistence of insect herbivores. Two sets of experiments will use caterpillars fed on plants and artificial diet to investigate how plant chemical defenses mediate herbivore-predator interactions and herbivore immune response to parasitoid threat. Using both laboratory and field experiments, the project examines how plant secondary metabolites mediate herbivore performance on different host plants and how those compounds further influence herbivore interactions with higher trophic levels. The project will advance both basic and applied ecology by examining the entire food web within which insects live. It will improve an ongoing dissertation research, thereby enhancing the training and expertise of a talented, early career, female researcher. The charismatic appeal of wildflowers and butterflies extends the educational impacts of the project to undergraduate students as well as to K-12 teachers and students. Undergraduate students will have the opportunity to work on independent projects, gaining hands-on experience with research, and an insect education program designed for elementary schools that is under development will capture students' interest and provide stimulating educational materials.