Abstract In recent study, phosphine resistance was assessed in 14 populations of Trogoderma granarium collected from North India. These populations were resistant to phosphine as compared to susceptible laboratory population and the resistance ratios at LC50 ranged from 1.16 to 31.62-fold. In order to determine the trend and magnitude of evolution of phosphine resistance under laboratory conditions, phosphine resistant strain of T. granarium was developed in the laboratory by subjecting the parental strain to a selection pressure of 70% in each generation for ten successive generations. Resistant strain showed 12.74-fold resistance as compared to parental strain. Specific activity of antioxidant enzymes viz., catalase, peroxidase and superoxide dismutase was measured in both collected populations and successive generations, and correlated with phosphine resistance. Specific activity of peroxidase and superoxide dismutase was increased significantly with an increase in phosphine resistance (P