Residual toxicity of different insecticides against tobacco caterpillar

The present investigations were carried out at CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur during summer and winter seasons of the year 2015 under polyhouse conditions. Tomato leaves sprayed with insecticides viz., flubendiamide (0.008%), imidacloprid (0.018%) drenching as well as spray, indoxacarb (0.015%), lambda-cyhalothrin (0.004%), malathion (0.050%), novaluron (0.010%) were brought to the laboratory at 0, 1, 3, 5, 7, 10 and 15 days after spray for testing the residual toxicity of insecticides against 2^nd instar Spodoptera litura larvae. Treatments were incubated at 25±1°C and 75±5% relative humidity and mortality of larvae was recorded after 24 h in all the insecticide treatments but in case of novaluron it was taken after 72 h of treatment. The mortality data were subjected to angular transformation and were statistically analyzed. On the basis of persistent toxicity values, the order of toxicity against 2^nd instar S. litura larvae was flubendiamide > indoxacarb > novaluron > malathion > lambdacyhalothrin > imidacloprid drenching > imidacloprid spray and flubendiamide > indoxacarb > novaluron > lambda-cyhalothrin > malathion > imidacloprid drenching > imidacloprid spray during summer and winter season, respectively.