Sublethal Effects of Insecticides on Rice Planthoppers: Implications for Pest Management and Agricultural Sustainability

ABSTRACT Rice planthoppers, including Nilaparvata lugens (Stål), Laodelphax striatellus (Fallén), and Sogatella furcifera (Horváth), pose substantial threats to global rice production through direct feeding damage and transmission of viral diseases. Although chemical control remains the primary management approach, insecticide concentrations below lethal levels (also referred to as ‘sublethal doses’) produce significant biological effects that extend well beyond immediate mortality. This review synthesises current knowledge on how sublethal insecticide exposure fundamentally alters rice planthopper biology through multiple pathways, including nerve system disruption, hormonal imbalance, cellular stress, and heritable genetic changes. Sublethal exposure modifies rice planthopper behaviour by disrupting feeding activity and movement coordination, while simultaneously activating detoxification enzyme systems (cytochrome P450s, glutathione‐ S ‐transferases, and carboxylesterases) that promote insecticide resistance. Reproductive impacts are substantial, with egg production commonly reduced by more than 60%, alongside delayed egg‐laying and damaged ovarian tissues. Interestingly, low doses occasionally stimulate increased reproduction, causing temporary population increases. Developmental effects include prolonged immature stages, enhanced production of winged forms capable of long‐distance migration, and impacts that persist across multiple generations through epigenetic mechanisms. The ecological consequences including pest resurgence, secondary pest outbreak, and impact on non‐target organisms are equally important. Insecticides affect natural enemies (predators and parasitoids) more severely than pests and as a result, surviving rice planthopper populations can rebound rapidly when predation pressure decreases. Broad‐spectrum insecticide applications also enable formerly minor pests to become major problems. Furthermore, beneficial organisms such as pollinators, parasitic wasps, and aquatic predators suffer collateral damage, compromising essential ecosystem functions and creating feedback loops that progressively reduce pesticide effectiveness. Following this review, sustainable rice planthopper management requires integrated strategies combining resistant rice varieties, biological control organisms, precision application technologies, and innovative approaches such as RNA interference‐based biopesticides. Future research should prioritise quantifying impacts on beneficial insects, understanding molecular mechanisms of transgenerational effects, and developing practical decision‐support tools for farmers.