Pesticide Research Journal

A study was conducted to determine the contact toxicity of four insecticides viz., deltamethrin, fipronil, chlorantraniliprole and abamectin against 10 and 5 d old larvae of Bihar hairy caterpillar, Spilarctia obliqua Walker by residue contact bioassay method in glass petridishes. On the basis of LC₅₀ values at different time intervals, the order of toxicity was deltamethrin > abamectin> fipronil with LC₅₀ values of 0.66, 25 and 650 ppm at 24 h after exposure, respectively. Deltamethrin caused 50% mortality in 13.46 h at 2 ppm, whereas fipronil took 12.37 h at quite higher concentration of 800 ppm. Abamectin was quicker in contact action than fipronil, in causing 50% mortality at 200 ppm in 6.4 h. The bioefficacy studies involving younger larvae (5 d old) of S. obliqua indicated lower LC values and quick contact toxicity at 12 h of exposure (>80% mortality).