SUSCEPTIBILITY AND IRRITABILITY LEVELS OF MAIN MALARIA VECTORS TO SYNTHETIC PYRETHROIDS IN THE ENDEMIC AREAS OF IRAN

Abstract- The rational use of insecticides largely depends on a broad knowledge of the susceptibility and irritability levels of malaria vectors to currently used insecticides especially pyrethroids. In this study the susceptibility and irritability levels of Anopheles stephensi and An.culicifacies to DDT 4%, malathion 5%, propoxur 0.1%, deltamethrin 0.025%, lambdacyhalothrin 0.1%, cyfluthrin 0.1 % and permethrin 0.25 % were determined. Susceptibility and irritability tests on adult mosquitoes were carried out according to WHO methods. The results showed that An.stephensi was resistant to DDT 4 % and mortality rates to this insecticide in Gavdary and Abtar areas were 64.2%±3.9 and 61.8%±4.36, respectively. An.stephensi was assumed susceptible to other insecticides. An.culicifacies was found susceptible to all the tested insecticides. The irritability tests carried out with pyrethroids exhibited that permethrin 0.25 % had the highest irritancy effect against both species. Lambdacyhalothrin 0.1 % and deltamethrin 0.025 % had the least irritancy effect against An.stephensi and An.culicifacies, respectively. Average numbers of take offs/females/minute of An.stephensi to permethrin, deltamethrin, cyfluthrin and lambdacyhalothrin were 6.64±1.04, 3.11±0.67, 2.73±0.61 and 2.57±0.67, respectively. These figures for An.culicifacies were 2.24±0.37, 1.44±0.38, 1.59±0.35 and 1.46±0.5, respectively. Irritancy effect of pyrethroids should come in consideration while they are used for control of malaria vectors