Insecticide Resistance in Cotton Aphid, Aphis gossypii

The study on insecticide resistance in cotton aphid, Aphis gossypii during Kharif, 2005 to five commonly used insecticides in cotton ecosystem, viz., monocrotophos, acephate, dimethoate, phosphamidon and triazophos revealed a shift in the level of susceptibility to these insecticides. The LC₅₀ and LC₉₀ values were increased 121.50, 20.00, 9.61, 7.96, 2.38 and 7.68, 3.84, 1.66, 0.60, 0.46 folds to the respective insecticides. A comparison of LC₉₀ values with recommended concentrations of test insecticides also revealed that aphid population of Guntur district developed resistance to all the test insecticides.