Impact of Insecticides Treatment on the Population Build UP of Myzus Persicae (Sulzer) and its Natural Enemies on Potato Crop in Karnataka

Studies on population buildup of M. persicae (Sulzer) in potato sprayed with insecticides (monocrotophos, dimethoate. methyl parathion and carbaryl) revealed that aphids did not occur upto 4th week. Aphid population reached to 58/100 compound leaves between 6th and 7th week after planting in unsprayed plots and l000/aphids/100 compound leaves in sprayed plots. The population of common predator Coccinella septumpunctata was very low in both the conditions. However, the population of para-sitoid, Aphidius colemani Vierick was higher in insecticide treated plots. From three years observations, it can be concluded that indiscriminate use of these broad spectrum insecticides has resulted in very high population build up of M. persicae.