Bio-efficacy and Economic Analysis of Novel Insecticide Molecules against Rice Leaf Folder Complex under Bhubaneswar Conditions

Abstract

Rice (Oryza sativa L.) is a major staple crop, but its productivity is significantly constrained by insect pests, particularly the leaf folder (Cnaphalocrocis medinalis), which can cause substantial yield losses. Effective pest management strategies that balance insecticide efficacy with conservation of natural enemies are essential for sustainable rice production. A field experiment was conducted during the Kharif season of 2022 at the research plot of the Entomology department, Odisha University of Agriculture and Technology (OUAT), Bhubaneswar, to evaluate the bio-efficacy and economics of novel insecticide molecules against rice leaf folder, Cnaphalocrocis medinalis (Guenee), and its natural enemies. The study utilized a Randomized Complete Block Design with eight treatments and three replications using the variety ‘Swarna.’ Evaluated insecticides include lamba-cyhalothrin 2.5%EC, flubendiamide 20%WG, flonicamid 50%WG, indoxacarb 15.8%EC, cartap hydrochloride 50%SP, emamectin benzoate 5SG, and chlorantraniliprole 18.5%SC. Flubendiamide 20%WG @125g/ha demonstrated superior bio-efficacy, recording the lowest leaf damage (1.09%) and the least larval population (0.20 larvae/hill) after two sprays. This was followed by indoxacarb 15.8%EC, which recorded 4.55% leaf damage and 0.41 larvae/hill. Safety assessments revealed that chlorantraniliprole 18.5% SC was the most compatible with natural enemies, supporting the highest predatory spider population (0.70 spiders/hill) 14 days after the second spray. Economic analysis showed that flubendiamide treated plots registered the maximum grain yield (49.24 q/ha), which was statistically at par with indoxacarb (48.92 q/ha). However, indoxacarb 15.8%EC achieved the highest incremental benefit-cost ratio (ICBR) of 1:2.06), compared to 1:1.67 for flubendiamide. While flubendiamide provided maximum knockdown, its higher toxicity to spiders (89.36% reduction) makes it less ideal for integrated pest management. Consequently, indoxacarb 15.8%EC is recommended for sustainable rice cultivation as it provides the optimal technical balance between high pest control efficacy, moderate safety to predatory spiders (0.45 spiders/hill), and maximum economic profitability.