Monitoring of insecticide resistance in fall armyworm, Spodoptera frugiperda (J. E. Smith) (Noctuidae: Lepidoptera)
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Date
2020-10-27
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University of Agricultural Sciences, Bangalore
Abstract
Monitoring of insecticide resistance in the fall armyworm, Spodoptera frugiperda (J. E.Smith) against commonly used insecticides were studied at the Department of Agricultural Entomology, UAS, GKVK, Bangalore. The six field populations of S. frugiperda collected from Bangalore Urban, Bangalore Rural, Bagalkote, Chikkaballapur, Raichur, Ramanagara and laboratory population were obtained from ICAR- NBAIR and LC50 for insecticides was determined using the surface coating diet method of bioassay. The lowest and highest LC50 values were recorded in emamectin benzoate (0.43-1.51 ppm) and Bt (39-117.27 ppm) respectively. LC50 of remaining insecticides, spinetoram (3.69-11.28 ppm), chlorantraniliprole (16.93-39.42 ppm), lambda-cyhalothrin (7.18-23.25 ppm), azadirachtin (5.30-17.89 ppm). This investigation showed that emamectin benzoate was highly toxic and Bt was less toxic to fall armyworm. Moreover, differences in LC50 values for given insecticides across populations were very low, denoting similar susceptible populations occurring in various locations. In the present investigation, the results of enzyme quantification indicated a positive increase in enzyme activity among field populations in Carboxylesterases and Glutathione-S-Transferase (GST), wherein Cytochrome p450 monooxygenases varied. Bangalore Rural population showed the highest carboxylesterases activity (1.32 μmoles min-1mg-1protein) and less activity was showed by the Chikkaballapur population (0.76 μmoles min-1mg-1protein).Chikkaballapur population showed higher activity of GST (11.99 μmoles min-1mg- 1protein) and the Bagalkote population showed less activity with 3.13 μmoles min-1mg- 1protein. In Cytochrome p450 monooxygenases, only the Chikkaballapur population (145.57 μmoles min-1mg-1protein) showed the highest activity than the laboratory population (93.98 μmoles min-1mg-1 protein), in the remaining field populations less activity was seen than the laboratory population.