This study aims to evaluate the toxic effects of organophosphate insecticide triazophos, biopesticide spinosad, and a pyrethroid insecticide cypermethrin on benthic Oligochaete worm, Branchiura sowerbyi during 96 h acute exposure. B. sowerbyi were exposed to two different sub-lethal concentrations (10% and 50% of 96h LC50) of triazophos, spinosad, and cypermethrin for 96 h in laboratory conditions. Catalase (CAT) activity of the control and treated worms were evaluated after 24 and 96 h of exposure. Integrated biomarker response (IBR) was applied for comparison between these three toxicants. For all sub-lethal doses i.e. 2.25 mg.L-1 and 0.5 mg.L-1 of test chemical triazophos, 3.07 mg.L-1 and 0.6 mg.L-1 of test chemical spinosad, and 0.38 mg.L-1 and 0.08 mg.L-1 of test chemical cypermethrin, catalase (CAT) activity raised significantly (p<0.05) in the treated worms in compare to the control worms. This study shows that toxicants including Triazophos, spinosad, and cypermethrin cause a large increase in catalase (CAT) activity in Branchiura sowerbyi, which is likely due to the toxicant’s increased ROS creation neutralizing the negative effects. IBR analysis aids in the differentiation of these three compounds’ harmful effects. As per IBR analysis, the rank of the toxicants is Cypermethrin > Triazophos > Spinosad.