Insecticide resistance status of Tuta absoluta (Lepidoptera: Gelechiidae) and mechanisms involved in resistance
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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران
نویسندگان
Department of Plant Protection, Faculty of Agriculture, University of Tabriz, Tabriz, Iran,
چکیده
The tomato leaf miner, Tuta absoluta, is a major destructive pest of tomato plants that has rapidly expanded in range. Low efficacy of available insecticides against the pest resulted in its control failure has been reportedly noted by experts and farmers. In this study, the toxicity of chlorpyrifos, deltamethrin, indoxacarb and chlorantraniliprole was determined against second instar larvae of two Iranian greenhouse populations of T. absoluta from Soufian (SF) and Qom (QM) using a leaf-dip bioassay. The resistance status of the populations was investigated through synergism assays. The synergists used were PBO, DEF, DEM and TPP which are inhibitors of cytochrome P450-dependent monooxygenases, esterases, glutathioneS-transferases and carboxylesterases, respectively. Reduced susceptibility to the insecticides studied was observed in Soufian and Qom populations compared with the susceptible population which was reared in greenhouse for three years without exposure to any insecticides. In Qom population, the highest resistance ratio (RR50) belonged to indoxacarb (14.91) followed by chlorpyrifos (4.46), chlorantraniliprole (4.42) and deltamethrin (2.06). The highest RR50 in Soufian population belonged to chlorantraniliprole (8.37) followed by chlorpyrifos (7.41) and indoxacarb (6.71). In SF population, RR50 for deltamethrin could not be estimated due to leaf damage caused by the high concentrations of this pyrethroid insecticide. In QM population, indoxacarb and chlorpyrifos were more toxic in presence of PBO than its absence showing synergistic ratios of 6.53 and 5.44, respectively. In addition, using PBO in SF population, the effects of chlorantraniliprole and chlorpyrifos were increased 5.14 and 4.86 times, respectively. The other synergists did not increase the toxicity of the insecticides tested. Provided that similar results are obtained in commercial greenhouse and field scale, these results can be useful in insecticide management of T. absoluta.
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