Efficacy and Economics of Different Insecticides Against Stem Borers, Scirpophaga incertulas (Walker) in Rice Crop

The present study on the efficacy of insecticides in reducing the infestation of rice stem borer, Scirpophaga incertulas (Walker) was conducted during 2008. The seed of rice (Cv. IRRI-6) was sown in the fourth week of June and transplanted in the fourth week of July. The distance between row to row and plant to plant was maintained at 20cm. The experiment had fourth treatments replicated four times in Randomized Complete Block Design. Pretreatment observation was taken 24 hrs before application of insecticides. At the time of harvest the number of filled grains and yield was recorded. The results obtained indicated that application of insecticides significantly (P<0.05) reduced the infestation of rice stem borer in rice crop compared with control treatment. After second application cartap hydrochloride was found most effective insecticide with the minimum percent infestation (4.37%) followed by carbofuran (7.08%), fipronil (8.68%) and control (38.53%). Application of insecticides also significantly (P<0.01) increased the filling of rice grain and yield of rice crop. The maximum cost: benefit ratio of 1: 50.3 was obtained with application of cartap hydrochloride followed by carbofuran (1: 26.45) and fipronil (1: 24.24).