Effect of fury, a synthetic pyrethroid, on esterases of different developmental stages of stored grain pest, red flour beetle, Tribolium castaneum (Herbst.) - spectrophotometric analysis

The effect of sub-lethal doses of Synthetic Pyrethroids insecticide Fury has been checked on esterases of Tribolium castaneum collected from stored grain godown and compared with those of insecticide resistant (CTC-12) and susceptible (FSS-II) strains to recognized insecticide resistance of the pest and hence suggested alternate control measures. The different types of esterases and total soluble protein activities were determined biochemically, using spectrophotometer. The total soluble protein contents significantly decrease (30%), after Fury treatment in 4th instar larvae whereas newly emerged adults and 15 days old beetles showed increase (28 and 12%). The various developmental stages of FSS-II and CTC-12 strains showed increase of total soluble contents after treatment with Fury. The Fury treatment however did not show any significant carboxylesterase (CE) activity in all the developmental stages of Pak strain. The 4th and 6th instar larvae of FSS-II and 4th instar larvae of CTC-12 strain showed decrease CE activity, whereas all other developmental stages remained unaffected. After the treatment with Fury the AChE activity decreased significantly in all stages of the three strains except 15 days old beetles of Pak and CTC-12 strains. The Fury treatment resulted in increase of ChE activity in the larval stages of Pak and FSS-II, while the adult stages were not affected. In CTC-12 strain the ChE activity decreased (46 and 67%) significantly in the 4th instar larvae and newly emerged adult after Fury treatment whereas in 15 days old adult the ChE activity increased (40%) significantly. The arylesterase (AE) activity decreased (33%) in 4th instar larvae and increased (38%) in 6th instar larvae whereas the other stages remained unaffected of Pak strain after Fury treatment. The 15 days old beetles of FSS-II and 4th and 6th instar larvae of CTC-12 strain showed significantly decreased AE activity, while the other stages showed non-significant changes after treatment with Fury. The Fury treatment, caused decrease (15%) of total esterases (TE) in the 4th instar larvae of Pak strain, whereas 4th instar larvae, 6th instar larvae, newly emerged and 15 days old beetles of FSS-II strain showed decrease (17, 26, 20 and 36%) respectively. In CTC-12 strain the TE activity of 15 days old beetles increased (24%) after Fury treatment, while the remaining stages showed no significant change.