Synergistic effect of MnO2 nanoparticles in overcoming insecticide tolerance in Nilaparvata lugens induced by elevated CO2 concentrations

Elevated CO 2 (eCO 2 ) can alter insecticide efficacy and reduce insect susceptibility to insecticides, yet the performance of nanoparticle-assisted insecticide formulations under eCO 2 conditions remains poorly understood. Here, we investigated the effects of eCO 2 on clothianidin susceptibility in Nilaparvata lugens and evaluated the efficacy of MnO 2 nanoparticles (NPs) co-application. Population performance, detoxification-related responses, CYP gene expression, microbial community dynamics, and preliminary non-target toxicity were analyzed under ambient CO 2 (aCO 2 , 420 µL/L) and eCO 2 (800 µL/L) conditions. eCO 2 exposure was associated with an approximately 1.5-fold reduction in clothianidin susceptibility and altered microbial community composition, including enrichment of stress-associated genera such as Acinetobacter and Serratia . Co-application with MnO 2 NPs enhanced clothianidin efficacy, reduced population growth, fecundity, and longevity, and was linked to suppression of detoxification-related enzyme activities and CYP gene expression. MnO 2 NPs treatment also counteracted the microbial community alterations associated with eCO 2 , which may contribute to improved insecticide susceptibility. Acute toxicity assays in Bombyx mori showed low short-term toxicity of MnO 2 NPs, with larval mortality remaining below 5% even at 800 mg/L. These findings suggest that elevated CO 2 may influence insecticide susceptibility through physiological, detoxification-related, and microbiome-associated responses. MnO 2 nanoparticle co-application may therefore represent a promising strategy for improving pesticide performance under future climate change scenarios.