Integrating habitat suitability and crop exposure to assess agricultural risk posed by the leaf beetle Sagra femorata (Coleoptera: Chrysomelidae) under climate-change scenarios

CONTEXT Climate change may expand climatically suitable habitats for invasive agricultural pests, but habitat expansion alone does not necessarily represent crop-related agricultural risk. To address this distinction, we developed a production-weighted agricultural risk index for Sagra femorata , a leaf beetle primarily associated with leguminous crops, by integrating habitat suitability estimates with agricultural exposure. OBJECTIVE This study aimed to predict the current and future global habitat suitability for S. femorata under climate-change scenarios and quantify country-level crop-related agricultural risk using a proposed production-weighted agricultural risk index. METHODS Occurrence records were combined with bioclimatic and elevation variables to develop ensemble species distribution models (SDMs) using the maximum entropy and random forest algorithms. Models were projected under baseline climate conditions and multiple future climate-change scenarios for the near-future (2041–2070) and far-future (2071–2100) periods. Country-level habitat suitability was calculated as the proportion of national land area predicted to be suitable for S. femorata . Crop-related agricultural risk was quantified using a production-weighted index that integrated cropland-weighted habitat hazard, aggregated susceptible host-crop production, and the non-paddy cropland proportion. RESULTS AND CONCLUSIONS The ensemble model showed reliable predictive performance, with mean AUROC values >0.9 and TSS values >0.7. Under baseline conditions, occurrence risk was concentrated mainly in tropical and subtropical regions, with high suitable habitat proportions in Thailand (94.74%), Belize (93.42%), and Cambodia (90.74%). Future projections identified habitat expansions across parts of Asia, South America, and Africa; under scenario SSP5–8.5, the number of countries hosting high proportions of suitable habitat (>60%) increased from 15 under baseline conditions to 45 in near future. In contrast, crop-related agricultural risk showed a different pattern, with the highest baseline risk indices in Bolivia, Brazil, and Ghana. The countries with the highest habitat suitability differed from those with the highest agricultural risk. Future agricultural risk increased most strongly in Ghana, Côte d'Ivoire, Brazil, and other tropical crop-producing countries. SIGNIFICANCE These findings show that climate-driven habitat expansion should be interpreted together with agricultural exposure when assessing crop-related risk posed by emerging agricultural pests such as S. femorata . The proposed production-weighted agricultural risk index provides a crop-relevant basis for country-level prioritization of surveillance and preventive management, particularly where expanding suitable habitats overlap with high-production host-crop systems.