Effect of temperature and sublethal doses of malathion on perfomance and vector potential of Culex restuans and Aedes albopictus

Temperature and the chemistry of aquatic larval habitats used by vector mosquitoes are two major sources of environmental stress that significantly impact immature development rate and survivorship, as well as adult longevity, fecundity, and competency. While the effect of temperature on the life history attributes of many mosquito species is well documented, few studies have explored the acute and chronic interaction of temperature with sublethal doses of common insecticides. Our study provides insight into the environmental impact of pesticides on non-target organisms and, indirectly, how these interactions may affect adult fitness and transmission of arboviruses. We evaluated the effect of 3 temperature regimes (20, 25 and 30º) and 4 concentrations of malathion (a common organophosphate) on immature survivorship to adult stage, development time to adult stage, adult body size and adult longevity of sugar-starved Culex restuans Theobald and Aedes albopictus Skuse. Both of these species are common inhabitants of urban containers and may frequently encounter runoff of foliar treatments of insecticides under a wide range of ambient temperatures. Our preliminary results indicate that both individually and interactively, temperature and sublethal concentrations of malathion had significant effect on larval development time and adult longevity for both species. These results suggest that temperature and sublethal concentrations of insecticides may significantly affect adult mosquito fitness and their ability to transmit diseases.