Field-Weathered Toxicity of Insecticides to Aphid Predator, Coccinella Septempunctata Linnaeus

Abstract

Field-weathered toxicity of insecticides was studied on rapeseed leaves to aphid predator, Coccinella septempunctata Linnaeus at different intervals after spray during the years 1999 and 2000. At the recommended concentrations, higher mortality of the predator was observed with cypermethrin and malathion than dimethoate and methyl demeton up to 3 days after spraying. On the 7th day after spray, residues of cypermethrin and malathion did not cause any mortality to the predator. On the 15th day after spray, all the insecticides did not cause any mortality to the predator except dimethoate, which resulted in 6.67 per cent mortality during the 2^nd year. The descending order of toxicity to the adult predator was dimethoate > methyl demeton > cypermethrin > malathion.