Climatic Niche Dynamics and Potential Distribution of the Invasive Sweet Potato Weevil (Cylas formicarius) in China

To assess the potential risk of expansion of the sweet potato weevil (Cylas formicarius) in China under climate change, we combined principal component analysis in environmental space (PCA-env) with a Biomod2 ensemble model, using 173 occurrence records from its native range in India and its invaded range in China. We quantified the dynamics of the climatic niche between the native and invaded ranges and projected both current and future climatically suitable areas in China. Precipitation during the wettest month (Bio13), mean temperature during the driest quarter (Bio9), and isothermality (Bio3) were the key climatic predictors. Niche overlap between India and China was low (Schoener's D = 0.107). The invaded niche was characterized by high stability (0.991) with very limited expansion (0.009), indicating strong niche conservatism. However, a relatively high unfilling value (0.633) suggests that the species has not yet occupied all potentially suitable climatic space in China. The current suitable area was estimated at 37.55 × 10⁴ km², primarily concentrated in South China and the southeastern coastal region. Under future climate scenarios, suitable habitat is projected to expand overall, extending into Central, Eastern, and Southwestern China. This study provides a climate-informed forecasting framework for assessing the potential spread of C. formicarius in China and offers practical support for quarantine surveillance and region-specific management.