Climate-Driven Range Shifts in Insect Pests: Redrawing the Global Map of Crop Vulnerability

Abstract

Rising global temperatures, shifting precipitation regimes, and elevated atmospheric carbon dioxide are altering the geographic ranges, phenology, and population dynamics of insect pests that damage the world's major food crops. This review synthesises evidence on the physiological mechanisms, observed range shifts, and projected redistribution of agriculturally important insect species under contemporary and future climate scenarios. Poleward and altitudinal expansions have already been documented across multiple pest taxa, with average latitudinal displacement rates in the low single-digit kilometres per year, and modelling studies project further acceleration under mid- and high-emission trajectories. Case evidence from fall armyworm, cotton leafworm, maize stemborers, and several rice pests illustrates how thermal tolerance, developmental plasticity, and host-plant availability jointly determine the pace and direction of range change. Elevated carbon dioxide modifies host-plant nutritional and defensive chemistry in ways that can either suppress or, in some circumstances, enhance herbivore performance, complicating simple temperature-based forecasts. Economic assessments indicate that warming-driven increases in insect-mediated crop losses could reach double-digit percentage increases per degree Celsius for staple cereals, disproportionately affecting temperate breadbasket regions, while invasive insects already impose costs exceeding tens of billions of US dollars annually worldwide. Species distribution modelling, mechanistic niche models, and hybrid approaches are increasingly used to anticipate these shifts, though model uncertainty, incomplete occurrence data, and neglect of biotic interactions remain persistent limitations. The review closes by identifying priority research directions, drawing overall conclusions for policy and practice, and acknowledging the methodological limitations inherent to a narrative synthesis of a rapidly evolving evidence base.