Effects of diapause on the excretory physiology of the northern house mosquito, Culex pipiens

Culex pipiens is the primary mosquito vector of West Nile virus and other encephalitis viruses in North America. Adult female Culex mosquitoes transmit these pathogens to vertebrate hosts during blood feeding or they can serve as a reservoir for the pathogens when they overwinter in a dormant state called diapause. Thus, diapause is an important physiological process to study as it may lead to novel methods for controlling disease transmission. Previous studies have shown that diapausing mosquitoes reserve more cuticular fat and thus reduce evaporative water loss in winter. However, it is unknown whether there is a corresponding decrease in water loss through the renal excretory system, which is mediated by the Malpighian tubules. The tubules produce urine by the transepithelial secretion of salts and water from the hemolymph to the tubule lumens and the urine passes to the hindgut and rectum, which eject it out of the body. The goal of my proposed research is to test the hypothesis that diapausing mosquito decrease the excretory capacity of their Malpighian tubules as a way to conserve water over the winter. Furthermore, I will test the hypothesis that the excretory capacity of the tubules is modulated by the molecular expression of aquaporin water channels (AQPs), which are proteins that mediate the water flow across cell membranes.  By conducting this study, I hope to 1) better understand the overwintering physiology of mosquito vectors and 2) reveal a potential novel approach for vector control by disrupting the ability of mosquitoes to conserve water during the diapause and thereby limit their capacity to serve as reservoirs for viral pathogens.