Susceptibility of Spodoptera litura (Fabricius) from Tarai region to insecticides and its esterase profile.

Studies were carried out to monitor the level of esterase activity at different age intervals of Spodoptera litura and to determine the relative susceptibility of seven day old larvae against six different synthetic insecticides. The esterase activities at different stages of S, litura showed that it keeps on increasing. The activity slightly increased from 2nd to 4th day i.e 0.120- 0.158 i moles/mg/min. and from the 5th day, there was drastic increase. Indoxacarb followed by emamectin benzoate were the most effective. The data on relative toxicity to cypermethrin showed that except fenvalerate all other insecticides viz., lambda cyhalothrin, profenophos, indoxacarb and emamectin benzoate were 1.21, 2.45, 7.20 and 2.87 fold toxic to S. litura, respectively.