Insecticide Toxicity to Coccinella septempunctata by Poisoned Food and Direct Exposure Under in Vitro Conditions

摘要

Eight different insecticides, endosulfan, dimethoate, oxydemeton methyl, monocrotophos, phosphamidon, imidacloprid, neem pesticide and profenophos were tested for toxicity to 3rd and 4'1' instar, and adult of Coccinella septempunctata, a commonly found predator on several pest insects in wheat. The insecticides were uniformly sprayed on different stages of predator and the food was given either in the form of insecticide treated or untreated aphids in order to simulate the natural conditions. All thetest insecticides caused mortality to the grubs and adults. The mortality increased with the exposure time, highest being after 72 h/7 days of treatment. Irrespective of the insecticide, the mortality of the third instar grubs (52.2%) was higher than that of fourth instar grubs (44.3%) followed by adults (41.4%). Mortality in all the stages was higher when treated aphids were given as food as compared untreated aphids. Profenophos caused maximum mortality (81 to 91%) followed by monocrotophos (77 to 82%), oxydemeton methyl (63 to 80%) and dimethoate (35 to 67%) to all the stages of the predator, while neem pesticide (11 to 27%), imidacloprid (18 to 32%) and endosulfan (29 to 41%) were categorized as comparatively less toxic to the predator and can beintegrated into the IPM component of wheat to encourage the population build up of the predator and natural check of aphids.