Comparative efficacy of new-generation insecticides against lepidopteran pests and their impact on natural enemies in rice ecosystem

The efficacies of some new-generation insecticides against the yellow stem borer, Scirpophaga incertulas, and the rice leaf folder, Cnaphalocrocis medinalis, and their impact on natural enemies in cultivated rice were evaluated during two consecutive wet seasons, i.e. 2022 and 2023. Among the treatments, tetraniliprole 18.18% SC @ 50 g a.i./ha was the most effective treatment, resulting in the lowest cumulative infestation of both the lepidopteran pests with 0.46% dead hearts (DH), 1.19% white ear heads (WEH) and 0.05% leaf folder damage leaves (LFDL), which was closely followed by rynaxypyr 18.5% SC @ 30 g a.i./ha and spinetoram 11.7% SC @ 23.4 g a.i./ha. Whereas, the untreated control was recorded with maximum DH (7.50%), WEH (14.54%) and LFDL (4.99%). Besides this, tetraniliprole 18.18% SC was relatively less harmful among the tested synthetic insecticides for natural enemies with cumulative numbers of 2.61 spiders/ 10 hills, 8.08 mirid bugs/ 10 hills and 1.67 carabid beetles/ 10 hills. The highest yield (4.98 t/ha) was recorded in the tetraniliprole 18.18% SC treatment, which was also the most biologically effective treatment for managing rice stem borer and leaf folder. However, cartap hydrochloride 50% SP was the most economically efficient treatment, with the highest incremental cost-benefit ratio (ICBR) of 1:7.26.