Evaluation of insecticide susceptibility and biological fitness of the brown planthopper Nilaparvata lugens under different warming exposure regimes

BACKGROUND: Global warming is expected to alter insect fitness and insecticide efficacy, yet the effects of different durations of warming exposure remain unclear. This study evaluated the effects of four warming exposure regimes (acute warming, AW; developmental warming, DW; transgenerational warming, TW; and parental warming, PW) on the population fitness and insecticide susceptibility of the brown planthopper, Nilaparvata lugens, a major rice pest in Asia. RESULTS: AW transiently stimulated reproduction and extended adult longevity. Conversely, sustained warming over one generation (DW) or two generations (TW) induced a resource trade-off marked by the up-regulation of thermotolerance genes and the down-regulation of cytochrome P450 detoxification genes, resulting in diminished fecundity, delayed development, and heightened sensitivity to multiple insecticides. Restricted warming to the parental generation, followed by a recovery generation at normal temperature (PW), restored reproductive performance and insecticide susceptibility to control levels. CONCLUSION: Temporal warming regimes significantly modulate the fitness and insecticide susceptibility of N. lugens. These findings underscore the need to consider not only the magnitude but also the duration and warming regimes when predicting pest population dynamics and designing pest management strategies that are resilient to climate change. © 2026 Society of Chemical Industry.