Pesticide Research Journal

Potculture and field trials were conducted to find out the impact of various insecticides on insect tesistance imparting plant chemicals viz., phenols and gossypol in cotton. Among synthetic insecticides, synthetic pyrethroids such as cypermethrin and deltamethrin reduced the total phenols content of leaves to a greater extent. Chlorpyriphos, oxydemeton-methyl and deltamethrin had a greater impact on gossypol content of cotton leaves. The biopesticides such as neem and Bt did not have any significant adverse effect on these biochemicals. In field studies, more whitefly population was observed in plots sprayed with synthetic pyrethroids. This indicated that the decrease in phenols content (responsible for resistance in plants against whitefly) of cotton plant due to spray of synthetic pyrethroids may be one of the important reasons for the resurgence of whitefly population.