This award provides partial support for Professor Marc J. Klowden, Division of Entomology, University of Idaho, to spend his sabbatical in the laboratory of Hans Briegel, Institute of Zoology, University of Zurich. They share an interest in how endogenous factors regulate insect behavior, and they will collaborate in a study of how several humoral factors, present during egg development in the mosquito, inhibit host seeking and increase the attraction to oviposition sites. Professor Klowden's approach until now has largely been to use microsurgery, involving gland ablation and transplantation. Through collaboration with Dr. Briegel and others at Zurich, he expects to learn their biochemical approach, including techniques for fractionating the components in the male accessory glands. His research goals for this six-month visit are to extract the accessory gland components of male Aedes aegypti mosquitoes, test the individual components for their behavioral effects in gravid females, and identify the components that show activity in the pre-oviposition bioassay. Although pre-oviposition behavior does not directly influence the vector potential of a mosquito population, it is a major factor in reproductive success and the maintenance of adult population densities. In order to understand better the epidemiology of mosquito-borne diseases, it is helpful also to understand the mechanisms that control mosquito behavior and how the female comes to express a particular behavior at a particular time. It is conceivable that natural products could be identified that interfere with the pre-oviposition behavior of many different insects; however, the mechanisms that regulate this behavior need to be understood first. This research will contribute to that goal.