Toxicity of Some Insecticides Against Tribolium Castaneum

Ten days old adult beetles and sixth instar larvae of two strains of Tribolium castaneum, namely, malathion-resistant (PAK) and organophosphate-susceptible (FSS-II) were exposed, for 48 hours, to some insecticides bearing novel modes of action, viz., abamectin (Sure 1.8 EC), spinosad (Tracer 240 SC), indoxacarb (Steward 150 SC), and buprofezin 25 WP, by the residual film method, while, azadirachtin (Nimbokil 60 EC), and polychlorinated petroleum hydrocarbon (Tenekil 100 EC) by the filter-paper impregnated method, for the determination of LC50 values. Then the effects of LC10 and LC20 doses of each insecticide, on the activities/levels of total esterases (TE), carboxylesterases (CE), -amylase, glucoamylases, acid phosphatases (AcP), alkaline phosphatases (AkP), total proteins, soluble proteins, and free amino acids (FAA) were observed. Abamectin with LC50 remained the most toxic of all compounds followed by spinosad, indoxacarb, polychlorinated petroleum hydrocarbon, buprofezin and azadirachtin against adults and larvae of both the strains. In biochemical analyses, the insecticides caused disturbances in levels of aforesaid enzymes and protein molecules.