Bio-efficacy of Newer Insecticides against Rice Leaf Folder, Cnaphalocrocis medinalis (Guenée)

Abstract

A field experiment was conducted during the Kharif seasons of 2022 and 2023 at the Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, to evaluate selected insecticides against the rice leaf folder, Cnaphalocrocis medinalis, which is becoming a major concern in rice-growing areas. The experiment was conducted in a randomised block design with seven treatments and three replications. Cyantraniliprole 300 g/L OD was evaluated at 30, 45, 60 and 75 g a.i./ha and compared with fipronil 80% WG at 50 g a.i./ha, lambda-cyhalothrin 4.9% CS at 12.5 g a.i./ha and an untreated control. Two applications were made at 30 and 60 days after transplanting, and leaf damage was recorded before application and at 3, 7, 10 and 14 days after each spray. All insecticidal treatments reduced leaf damage relative to the untreated control. Cyantraniliprole applied at 45 g a.i./ha recorded the lowest overall leaf damage, with values of 7.78% in Kharif 2022 and 6.78% in Kharif 2023. The corresponding values for cyantraniliprole at 60 g a.i./ha were 8.04% and 7.59%, respectively. Fipronil was the next most effective treatment, with values of 8.38% and 8.42%, whereas lambda-cyhalothrin recorded comparatively higher leaf damage of 9.76% and 9.68%, respectively. Under the conditions of this field study, cyantraniliprole at 45 g a.i./ha provided consistent suppression of rice leaf folder across both seasons and produced the highest yields, at 4.09 and 4.26 t/ha, respectively.