Potentially Suitable Areas for Acanthoscelides obtectus (Say, 1831) in China Under Baseline and Future Climate Conditions Using an Optimized MaxEnt Model

Acanthoscelides obtectus (Say, 1831) threatens bean production and storage. We assessed its climatic suitability in China using an optimized maximum entropy (MaxEnt) model with seven bioclimatic variables. Final fitting used 342 spatially thinned occurrences and 10,000 background points sampled in proportion to cell area. Projections covered three global climate models, three Shared Socioeconomic Pathways (SSPs), and three future periods. Five-fold outer spatial validation yielded an area under the receiver operating characteristic curve of 0.78 ± 0.05 and a continuous Boyce index of 0.87 ± 0.10. Temperature annual range, maximum temperature of the warmest month, and mean temperature of the wettest quarter had the highest normalized permutation importance. Baseline projections (1970–2000) identified 3.02 million km2 of potentially suitable areas, mainly in southwestern and southern China and along the eastern coast. Under the primary M500 calibration, all nine ensembles showed total-area declines, high-suitability losses and westward centroid shifts. For late-century SSP5-8.5, the primary ensemble projected a 1.41% total-area decline and a 93.92% high-suitability loss (s ≥ 0.75). Total-area change reversed direction across backgrounds, GCM compositions and bootstrap fits, whereas westward shifts persisted. Centroid-shift direction was thus more consistent than area-change direction across these comparisons, informing climate-based surveillance.