DefinePK

Abstract

Using of insecticides depend largely on the knowledge of the susceptibility levels of malaria vectors to these chemical. In this study, the susceptibility levels of Anopheles stephensi to DDT 4%, dieldrin 0.4%, fipronil 1%, deltamethrin 0.05%, permethrin 0.75%, lambdacyhalothrin 0.05% and cyfluthrin 0.15% were determined according to WHO methods in three endemic malarious regions; Sistan and Baluchistan, Hormozgan and Fars provinces. The LT50 values of different insecticides were calculated using the probit regression line for each strain. The results showed that An. stephensi is resistant to DDT, dieldrin and fipronil in all regions; however Bandar Abbas strain showed the highest level of resistance to these three insecticides. All the tested strains were sensitive against four pyrethroid insecticides. The LT50 of Bandar Abbas strain against cyfluthrin and deltamethrin with 5.46 and 3.22 min were the highest and the lowest values respectively. The highest and the lowest mortality rates of the Kazeroon strain of An. stephensi were against lambdacyhalothrin and permethrin with 6.80 and 0.682 min, respectively. In Iranshahr region, the figures for deltamethrin, permethrin, lambdacyhalothrin and cyfluthrin were 3.50, 5.10, 3.95 and 5.38 min, respectively. The results of the study suggested a possible cross-resistance between dieldrin and fipronil. Regarding the sensitivity of An. stephensi to different pyrethroids in the malarious regions of Iran, using pyrethroids is still suggested. Performing complementary tests with cyfluthrin on Bandar Abbas strain and with permethrin on Iranshahr strain seems to be necessary.