Date of Award
Doctor of Philosophy
Thomas W. Sappington
Leslie C. Lewis
Transgenic, insecticidal corn hybrids (Bt corn) are a tactic for managing European corn borer, Ostrinia nubilalis (Hubner), in North America. To slow development of Bt-corn resistance, an Insect Resistance Management plan requires monitoring and nearby refugia. We examined the effect of feeding diet incorporated with Cry1Ab on growth, development, and survival of Nosema-infected and uninfected O. nubilalis. Increasing concentrations of Cry1Ab in diet reduced larval growth and development rates, and this phenomenon was amplified by micro sporidiosis. This work demonstrates that it is important to determine whether pathogens are present when monitoring resistance;Pheromone-baited traps are used in O. nubilalis studies. However, differences in captures may be confounded by design, location relative to a windbreak, and changes in local weather. We examined differences in captures among wing traps, bucket/funnel traps, Hartstack wire-mesh cone traps, as well as among three cone trap designs. Second, we examined the influence of cone-trap location relative to windbreaks on numbers of moths captured. Third, we examined the relationship between nightly mean air temperature, relative humidity, wind speed, precipitation, and numbers of moths captured in cone traps. Numbers of moths captured was significantly influenced by trap design, with cone traps capturing the most moths. Under strong or moderate wind speeds, traps located leeward of windbreaks captured the most moths, but when wind speeds were light, traps not associated with windbreaks captured the most moths. Changes in numbers of moths captured on a given night were related weakly to weather. Air temperature parameters were consistently most influential in the regression models, and their relationship with moth captures was positive;Determining the appropriate distance between refugia and Bt corn, and development of mitigation-remediation strategies, requires knowledge of adult dispersal and mating behavior. We examined influences of pheromone lure, plant density, and plant species on distributions of feral and newly-emerged, laboratory-reared O. nubilalis among small-grain aggregation plots. The majority of adults did not colonize aggregation plots, suggesting that recently-eclosed adults leave their natal field and do not colonize the first aggregation sites encountered. Mass releases of laboratory-reared pupae in the field may not be a viable resistance-remediation tactic.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Brendon James Reardon
Reardon, Brendon James, "Ecological studies of the European corn borer (Lepidoptera: Crambidae): nosema dose-response, pheromone trapping, and adult dispersal " (2006). Retrospective Theses and Dissertations. 1293.