Biochemical assay baseline data of permetrhrin resistance in Anopheles stephensi (Diptera, Culicidae) from Iran

Abstract

Bioassays were performed on 1-2 days old sugar fed adult mosquitoes of field and susceptible Beech strains of An. stephensi using WHO standard kit with some modifications. The KT50s of exposure to 0.08% permethrin impregnated papers were 40±1, 43±1 and 44±2 for susceptible, Kazeroun and Bandar Abbas strains, respectively. Biochemical assays of esterases, monooxigenases and glutathione S-transferases were undertaken on An.stephensi from Kazeroun and Bandar Abbas and the results were compared to those of the susceptible Beech strain. The mean alfa-esterase activity of Kazeroun, Bandar Abbas and Beech strains were 6.5×10-2, 7.1×10-2 and 6.1×10-2; the mean beta-esterase activity in those strains were 7.2×10-3, 3.2×10 -3 and 2.4×10-3; the mean content of p450 in the above-mentioned strains were 8×10-3, 4.6×10 -3 and 3.4×10-3; the mean GST activity were 8.7, 10.5 and 3.6, respectively. Although according to the results of this study, An. stephensi from Iran is not considered to be resistant to pyrethroids, the results of bioassays and the mean activity of all enzyme groups in field strains were significantly different from those of the susceptible strain. The results of bioassays were significantly different from those performed some 15 years ago on the same strains. Hence, insecticide resistance monitoring techniques should be put in place and also resistance management strategies and measures should be considered implementing in the area to prevent or postpone insecticide resistance development. © 2006 Asian Network for Scientific Information.