Recently, cotton production throughout the southern U.S. have declined substantially. Additionally, the pest status of bollworm, Helicoverpa zea (Boddie), has increased in soybean. As a result, there is growing interest to have commercial access to transgenic soybean varieties that express the Bt toxins to help manage against lepidopteran pests. However, soybeans are assumed to be a key host in the natural refuge concept used for Bt cotton. Research was conducted to determine if the introduction of Bt soybeans into the U.S. would present an unacceptable risk to the sustainability of other crops. This project examines the contribution of soybean to the susceptible heliothine populations in the natural refuge system, the potential of delayed in-season emergence of H. zea from field corn, effects of soil moisture on emergence and pupal duration, fitness of adult H. zea from Bt and non-Bt corn, and provide more accurate parameters for future resistance development models.