Assessment of baseline toxicity of newer insecticides for rice leaffolder Cnaphalocrocis medinalis (Guenee) (Lepidoptera: Pyralidae)

the acute toxicity studies on chlorpyriphos, cartap hydrochloride, chlorantraniliprole and profenophos to the target pest rice leaffolder, Cnaphalocrocis medinalis (Guenee) in order to fix the baseline data of these chemicals to calibrate discriminating dose indicated that the Lc50 and Lc95 obtained for subsequent six generations without selection pressure to insecticides like chlorpyriphos, cartap hydrochloride, chlorantraniliprole and profenophos (F11 to F16 generation) decreased from 20.146 to 15.334, 18.798 to 14.704, 2.559 to 2.246, 15.003 to 12.708 ppm and 55.815 to 45.759, 49.957 to 39.537, 4.334 to 3.519 and 43.532 to 35.788 ppm respectively showing gradual decline with generations. Considering the susceptible population of rice leaffolder, the tentative discriminating doses (DD) by seedling dip method to third instar larvae were 46, 40, 4 and 36 ppm for chlorpyriphos, cartap hydrochloride, chlorantraniliprole and profenophos, respectively.