Due to their bloodsucking habits, mosquitoes are disturbing annoyances to the public, as well as being the vectors of many serious diseases. Many of the species of mosquitoes which pose a health hazard in the United States breed in salt water. On the East Coast, saltwater mosquitoes occur in huge numbers in coastal marshes and their control is essential for the use and enjoyment of beaches and coastal waterways. In the West, salt-tolerant mosquitoes are the vectors of very serious diseases such as viral encephalitis and heartworm. The larvae of mosquitoes are aquatic. Dr. Bradley is investigating mechanisms used by salt-tolerant mosquitoes to survive in this harsh aquatic habitat. A better understanding of the mechanisms used by these mosquitoes may enable us to circumvent these mechanisms and/or predict the location of mosquitoes populations, thereby reducing these populations and directing control procedures to the sites where intervention is required. This proposal describe investigations into the mechanisms of osmoregulation in mosquito larvae. "Brackish-water" mosquito larvae are euryhaline osmoconformers by means of the accumulation of organic osmolytes in the hemolymph. Using the brackish-water species Culex tarsalis, Dr. Bradley will examine a) the time course and pattern of osmolyte regulation during changes in salinity, b) the role of the excretory system in eliminating or retaining osmolytes of low molecular weight and c) the osmolytes used intracellularly for volume and osmotic regulation. Phylogenetic evidence indicates that mechanisms associated with the brackish-water pattern of osmoregulation arose independently in two genera of mosquitoes. The Principal Investigator will compare the mechanisms employed by these independent lineages. The studies are designed to increase our understanding of the mechanisms of osmoregulation in a taxonomically restricted group of insects inhabiting a diverse range of osmoregulatory niches.
