Base Line Data for Insecticide Resistance Monitoring in Beet Armyworm, Spodoptera Exigua Hubner on Chickpea

Base line data on the susceptibility of beet armyworm, Spodoptera exigua, to diffefent toxicants belonging to diverse groups were generated for monitoring the development of resistance. The LC₅₀ values of indoxacarb, novaluron, emamectinbenzoate, lufenuron, spinosad, methomyl, deltamethrin, cypermethrin, profenophos, thiodicarb, quinalphos, chlorpyriphos, fenvalrate, endosulfan, and acephate were 0.029, 0.037, 0.04, 0.15, 0.9, 0.208, 0.239, 1.09, 1.51, 2.23, 3.9, 6.02, 6.16, 6.30 and 35.4 μg per larva, respectively. LC₉₀ values were also worked out. Taking LC₅₀ of cypermethrin as unity, relative toxicity of these chemicals was compared. Compounds with novels modes of action were found superior over conventional insecticides. Among all the tested chemicals indoxacarb was more toxic and acephate least toxic. The LC values obtained would serve as ready reckoner for the selection of insecticides for field strains. Also, such base line data could be used as critical inputs in the deployment of new insecticides and insecticide resistance management programmes.