Balancing pest control and biodiversity: Differential impacts of insecticides on arthropod diversity in direct-sown rice ecosystem

Abstract

The overreliance on insecticides for pest management in global rice production often overlooks their adverse effects on non-target arthropods, threatening agroecosystem stability. This study evaluated the differential impacts of six insecticides flubendiamide, triflumezopyrim, thiamethoxam, cartap hydrochloride, pymetrozine, and acephate on arthropod diversity across three growth stages in a direct-sown rice ecosystem during the 2023 kharif season. Arthropods were sampled using sweep netting, pitfall trapping, and Berlese funnel extraction. Results indicated that all insecticides suppressed both pest and non-target arthropod populations, but the magnitude of impact was compound and timing specific. Flubendiamide demonstrated high pest efficacy but was severely detrimental to non-targets, particularly during early tillering and ripening. Cartap hydrochloride was comparatively favourable to natural enemies in early stages, whereas thiamethoxam and acephate exhibited broad toxicity across growth stages. Unsprayed control plots consistently maintained the highest species richness and diversity indices. These findings highlight a critical trade-off between effective pest control and the conservation of beneficial arthropod biodiversity, underscoring the necessity of integrating selective insecticide use with stage-specific application within an Integrated Pest Management (IPM) framework to promote ecological balance in rice agroecosystems.