The World Health Organization's Roll Back Malaria Program relies heavily on the use of insecticide treated bednets (ITNs) to protect against malaria, and indeed preliminary studies have shown significant reductions in all cause childhood mortality in areas where ITNs have been used. The long-term goal of this application is to understand what adaptations in the Anopheline mosquito vectors of malaria might be selected for that would undermine the efficacy of UN-based malaria control programs. There is preliminary evidence in Ghana of at least 2 such adaptations. First, biochemical resistance to the pyrethroid insecticides used in ITN is emerging. Second, the peak feeding time of some Anopheline mosquitoes has shifted from midnight to between 0500-0600, when rural farmers are out of their beds. 2 communities in Northern Ghana with different histories of ITN use will be compared. The Kassena-Nankana District was 1 of the first sites for ITN use in Ghana and ITN have been widely used there for 10 years. ITN use in the nearby Bongo District began only recently and is still uncommon there. The following variables will be compared in the 2 districts: (1) species and host preference of Anopheline malaria vectors (2) prevalence of pyrethroid resistance (3) feeding and resting behavior biting cycle, and peak feeding times. Standard methods will be used for mosquito collection to determine host selection, biting rates, biting activities, resting habits, and room exiting behavior. Species-specific PCR primers will be used to identify members of the malaria vector species complexes and ELISA will be used to determine the source of blood meals. WHO bioassay and CDC bottle assays will be used to assess pyrethroid susceptibility or resistance. Resistance mechanisms will be studies using standard biochemical assays and PCR assays for kdr gene mutations. We will use these comparisons to ask whether ITN use has indeed selected for biochemical and/or behavioral adaptations in malaria vectors. ? ?
