Dissertation Research: Ecological Significance of Omnivory: The Role of Phytophagy in the Persistence of Omnivorous Predator-Prey Interactions

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9423543 Denno The persistence of predator populations is primarily determined by the resources available to the predator in a given environment. When resources decline, predators starve or emigrate and predator populations do not persist. Omnivorous predators, however, can escape starvation or preclude emigration by feeding on plants and persist in environments with low prey densities. When prey are scarce, with each additional prey item eaten, the omnivorous predator consumes an increasingly larger proportion of the prey population, further suppressing the prey population and ultimately resulting in the local extinction of the prey. Omnivorous predator-prey interactions have received considerable theoretical attention and there are numerous examples of omnivorous insects distributed among diverse taxa, however, no study has attempted to determine the importance of phytophagy in the persistence of both omnivore and prey populations. This dissertation research will examine the role of phytophagy in the population persistence of the omnivorous predator, the big-eyed bug, and its aphid prey, a significant pest on soybeans. A series of laboratory and field experiments will determine if the bug can survive periods of low food availability by eating different quality of plant material and different stages in the life cycle. This research will address important issues in predator-prey dynamics including the vital role of omnivory in maintaining predator populations during periods when prey items are scarce. In addition, this research will have direct applications related to biological control of aphid pests on soybeans, and the potential damage to soy beans caused by the control agent, rather than the aphid.