Laboratory evaluation of the efficacy of boric acid containing toxic sugar baits against Anopheles culicifacies, An. stephensi and Aedes aegypti mosquitoes

Background & objectives: Attractive toxic sugar baits (ATSB) is a novel tool which employs mosquito sugar feeding behaviour to kill them. The potential of ATSB against mosquito vectors has been demonstrated in limited scope around the world including Israel, some of the African countries and USA. But their efficacy against mosquito vectors of India is yet to be ascertained. Therefore, current study was planned to evaluate the efficacy of TSB (without attractant) against two important malaria vectors Anopheles culicifacies and An. stephensi along with major dengue vector Aedes aegypti. Methods: TSB solution was prepared by dissolving different concentrations of boric acid in glucose and tested against each of the mosquito species. Another experiment was done by spraying this boric acid sugar solution on to Calendula officinalis plant. It served as a sole source of mosquito feed and mortality of mosquitoes was counted after 24 hours. Results: The TSB resulted in 100% mortality of Ae. aegypti and An. stephensi at 4% concentration of boric acid while in An. culicifacies 100% mortality was achieved at 3% concentration TSB solution. TSB solution with 2% boric acid, resulted in 99.1% mortality in An. culicifacies while ~95 % mortality of An. stephensi and Ae. aegypti. When TSB solution with 2% boric acid was sprayed on plant, ~89-94% mortality was observed in both An. stephensi and An. culicifacies. Interpretation & conclusion: Based on the results, boric acid based toxic sugar bait solution could be a promising tool for vector control. Further studies are needed to find out its toxicity of TSB against non-target organisms and residual efficacy in field trials in different ecotypes.