This study will examine the relationship between migration and reproduction in an economically significant migratory grasshopper, Melanoplus sanguinipes. Previous work has shown that migratory behavior has a genetic basis in this species and that the performance of migratory flight significantly accelerates onset of reproduction and enhances fecundity over the entire life of the insect. This observation challenges the conventional assumption that migration necessarily involves a reproductive cost.
The proposal addresses two general objectives: to determine the endocrine mechanisms involved in flight-enhanced reproduction, and the possible effect of long-duration flight on nutrient acquisition or utilization. To accomplish the first objective, the effects of long-duration flight on the release or synthesis of neurohormones, that might in turn cause changes in the pattern and/or level of hormones involved in reproduction, will be determined. In pursuit of the second objective, the effect of flight performance on two avenues of nutrient acquisition, mating and feeding, will be determined. In the model species, males contribute nutrient to females at mating via spermatophore transfer with sperm. Thus, this study will establish whether the performance of long flight changes the frequency or duration of mating behavior after flight and if it does, whether this change is hormonally regulated. It has been shown that feeding activity does not increase after long flight, but this study now intends to establish whether performance of long-duration flight improves food utilization, and whether this occurs via endocrine stimulation.
A long-term goal of this project is to analyze the consequences and limits of these physiological relationships through genetic analysis. The results of this work will be of interest to population biologists studying life history theory and evolution, physiologists interested in understanding endocrine relationships in insects, physiological ecologists interested in resource allocation and coordination of life history characters, and entomologists interested in controlling M. sanguinipes and other serious agricultural pests. This project will involve minority and women undergraduates (usually 4 students/semester). It will also involve pre-service math and science high school and middle school teachers as research interns (2/semester) as a part of an innovative new teacher-training program (UTeach) at The University of Texas.