In order to study the effects of repeated use of various insecticides on thrips and their natural enemies viz., Ladybird beetle and Predatory spiders, an experiment was conducted during Kharif, 2018-19at the Experimental farm, Department of Agricultural Entomology, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani. The insecticides selected included those used commonly among the farmers viz., Imidacloprid SL, Fipronil 5% SC, Lambda cyhalothrin 5% EC, Spinosad 45% SC, Acephate 75% SP, Buprofezin 25% SC, Flonicamid 50% WG, Acetamiprid 20% SP, Profenofos 50% EC, Diafenthiuron 50%WP, Acephate 50% + Imidacloprid SP, Pyriproxyfen 5% + Fenpropathrin 15% EC and Profenofos 40% + Cypermethrin 4% the first spraying onwards, Flonicamid 50% WG was found to be the best in reducing the thrips population steadily up to in second spraying. But, a sudden increase in population mean was found in the third () and fourth spraying (). Same trend was followed in Fipronil 5% SC, Buprofezin 25% SC and Diafenthiuron 50% WP. The effect of repeated applications of synthetic insecticides on the natural enemies depicted that Spinosad 45% SC, Flonicamid 50% WG and Buprofezin 25% SC were the safest insecticides, showing maximum natural enemies population. Imidacloprid SL, Fipronil 5% SC and Lambda cyhalothrin 5% EC recorded minimum natural enemies population marking its intense toxicity against them. | Impact of repeated application of synthetic insecticides on thrips and their natural enemies of Bt cotton
