Climate and Cropland Jointly Shape Future Habitat Suitability of Major Stored-Product Callosobruchus Pests

Abstract

Stored-product insects threaten global food security, yet the environmental mechanisms governing their responses to climate change remain poorly understood. Existing pest distribution projections rarely integrate diurnal thermal variability with agricultural land use. Here, we show that diurnal thermal variability, together with agricultural land use, is a major determinant of habitat suitability for three globally important Callosobruchus pests across the Middle East. Using optimized species distribution models integrating climate, topography, and cropland under contrasting CMIP6 climate scenarios, we demonstrate that mean diurnal temperature range and cropland consistently emerge as the strongest predictors across all species, revealing the importance of daily thermal fluctuations beyond mean warming alone. Under the low-emission scenario (SSP1-2.6), suitable habitat by mid-century expands substantially for C. chinensis and C. phaseoli, while remaining little changed overall for C. maculatus, for which comparable local expansion and contraction largely offset one another; under the high-emission scenario (SSP5-8.5), gains are reduced, and localized contractions occur, particularly for C. chinensis and C. maculatus, the latter shifting to a slight net loss in total suitable area. Persistent climatic refugia remain along Mediterranean and Red Sea coastal regions, whereas habitat losses are concentrated in the northern Gulf lowlands and Zagros foothills. Our findings identify diurnal thermal variability as an overlooked dimension of stored-product pest ecology and show that integrating agricultural landscapes with climate projections can improve forecasts of future pest risk, providing a framework for climate-informed surveillance, biosecurity, and adaptation.