Susceptibility of malaria vectors to insecticides in Gumla district, Jharkhand state, India.

high prevalence period of respective vectors. Anopheles culicifacies, An. fluviatilis and An. annularis were collected from cattlesheds, human dwellings and mixed dwellings of different villages of each PHC during 0600–0800 hrs with the help of suction tube and flash light. The collected female mosquitoes were provided 10% glucose solution soaked in cotton pads and transported in caged cloth to the nearby field laboratory of the respective PHC. Insecticide susceptibility status of vector mosquitoes was determined using WHO specified insecticide impregnated papers with diagnostic concentrations of DDT (4.0%), malathion (5.0%), deltamethrin (0.05%) and cyfluthrin (0.15%) as per standard WHO technique 6 . After exposure for one hour the percent mortalities were calculated by scoring the dead and alive mosquitoes after 24 h of recovery period and corrected % mortality was determined using Abbott’s formula 7 . Results of susceptibility tests on An. culicifacies, An. fluviatilis and An. annularis against different insecticides tested are given in Table 1. The results revealed that An. culicifacies, An. fluviatilis and An. annularis were resistant to DDT and susceptible to deltamethrin, malathion and cyfluthrin. Statistical analysis revealed that there were no significant differences in mortalities among the mosquito species against malathion (χ 2 = 45.3; p <0.001), against deltamethrin (χ 2 = 9.92; p <0.05) and cyfluthrin (p <0.001) while between DDT and pyrethroids and malathion there is a vast difference (χ 2 =127; p <0.0001).