Effects of anthropogenic change on interactions between North American tephritid flies and their biotic associates
Anthropogenic environmental change is increasingly altering species ranges, community composition, and ecological interactions. Climate change, agriculture, invasive species, and human management of land all affect insect community dynamics, interactions between competitors and natural enemies, and invasive potential. In this thesis, I examine the effects of the following anthropogenic changes on tephritid fruit flies, Rhagoletis pomonella (Walsh) and Zonosemata electa (Say), and their competitors and natural enemies: climate change (simulated through an experimentally-induced heat effect), novel agricultural host plants, and land/weed management. R. pomonella is native to portions of North America and historically utilized hawthorn (Crataegus spp. (L.) fruits as its host. After the introduction of apples, a fruit larger than hawthorn berries, to North America by humans, R. pomonella made a host shift to apples, which provide a partial escape from natural enemies and competitors. Similarly, Z. electa made a host shift from native horsenettle, Solanum carolinense (L.)., fruits to introduced crops: peppers and eggplant. The first study employed experimental manipulation of temperature, sunlight, and fruit location to examine the effects of anthropogenic change and competition on parasitism, larval survival rates, and pupal weight in R. pomonella. The second study examined the effects of fruit location and trap baits (apples alone, apples with R. pomonella larvae, or R. pomonella pupae alone) on attraction to ants and also surveyed species composition in an unmanaged apple orchard. The third study surveyed Z. electa parasitism rates and infestation rates in S. carolinense. The results of the first study indicate that in R. pomonella the effects of temperature include lowering parasitism and larval survival rates, with interactions from the effects of competition. The results of the second study indicate that R. pomonella larvae are attractive to local ant species and that there are effects of tree location on ant attraction to baits. The results of the third study indicate that infestation rates of Z. electa in horsenettle are low compared to infestation rates in peppers and confirmed natural low parasitism rates by Diachasmimorpha sanguinea (Ashmead). These results combined provide a more complete overview of the effects of anthropogenic change on North American tephritids and their biotic associates and will inform future pest management strategies.
Tephritidae, Rhagoletis pomonella, Zonosemata electa, tephritid, natural enemies, Solanum carolinense, apple maggot, climate change
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign