Microtermes obesi belong to one such new clad of termite species which damages tea plantations of Darjeeling foothills. To control tea pests, planters use synthetic insecticides that have lead to the much bigger problem of insecticide tolerance in many tea pests. Present study contemplates to investigate the tolerance status of the pest species, collected from organically and conventionally managed tea plantations of Darjeeling foothills to three different commonly used insecticides – Imidacloprid 17.8% SL, Cypermethrin 35% EC and Chlorpyrifos 20% EC, along with the activity of the three major detoxifying enzymes, General Esterases(GE), Glutathion S Transferase (GST) and Cytochrome oxydases (CYP450). Results obtained showed higher level of mean lethal concentration (LC50) for Imidacloprid 17.8% SL = 63.66 ppm, Cypermethrin 35% EC = 31.99 ppm, and Chlorpyrifos 20% EC = 18.57 ppm in M. obesi population collected from conventionally managed tea plantations, as compared to that from organically managed plantations. Even observations on detoxifying enzymes reflected a corresponding enhancement in their activities which were noted as: GE = 2.25 mM mg -1 protein; GST = 120.86 µM min-1 mg-1 protein; CYP450 = 0.75 n mol min-1 mg protein-1 in population of pesticide managed conventional plantation, and at a lower level (GE = 0.23 mM mg -1 protein; GST = 16.73 µM min-1 mg-1 protein; CYP450 = 0.26 n mol min-1 mg protein-1) in population of organically managed tea plantation. Hence, developing an enzyme-based marker for M. obesi populations may be of practical use in titrating an effective pesticide dosage under IPM/IRM strategies.
