Beyond target-site resistance: Integrating epigenetic regulation, behavioural adaptation and eco-evolutionary dynamics of insecticide resistance

Insecticide resistance is commonly attributed to target-site mutations and enhanced metabolic detoxification; however, these mechanisms alone do not fully explain its rapid emergence, temporal instability, reversion in the absence of selection and variability among populations exposed to similar selection pressures. This review critically examines three complementary dimensions of resistance evolution: epigenetic regulation, behavioural adaptation and eco-evolutionary feedbacks between insect populations and agricultural landscapes. The resistance landscape across seven economically important crops - brice, maize, chilli, brinjal, groundnut, cotton and castor is assessed, with emphasis on major pests, including planthoppers, stem borers, fall armyworm, bollworms, whiteflies, thrips and tobacco cutworm. Emerging evidence for DNA methylation, non-coding RNAs, transposable-element-mediated regulatory changes, non-genetic inheritance and symbiont-mediated detoxification is evaluated alongside behavioural mechanisms that reduce insecticide exposure, including avoidance, altered feeding, oviposition-site selection and shifts in activity patterns. The review further analyses how fitness costs, gene flow, refuge dynamics, polyphagy across crop mosaics and climate change interact to shape resistance development, persistence and spread. To distinguish established mechanisms from emerging hypotheses, the strength of evidence is classified as strong, emerging, or speculative. Finally, research priorities and management strategies are identified to improve resistance surveillance, refine insecticide stewardship and strengthen integrated pest management. An expanded understanding of resistance beyond conventional genetic mechanisms could support more predictive, evolution-informed and sustainable crop protection, particularly in diverse smallholder farming systems.