Predicting Distributional Changes of Bactrocera diaphora (Hendel) (Diptera: Tephritidae) in China Using an Optimized MaxEnt Model

Bactrocera ( Zeugodacus ) diaphora (Hendel) is a quarantine invasive pest that causes substantial damage to fruit and vegetable crops. To assess its potential range in China under climate change, we compiled 83 occurrence records and calibrated a MaxEnt model using an optimized feature combination (LQP) and a regularization multiplier (RM = 0.5). Model validation yielded a mean AUC > 0.96, indicating excellent performance. Using current climate data and four CMIP6 scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5) for four future periods (2021–2040, 2041–2060, 2061–2080, and 2081–2100), we projected current and future suitable habitats in China. Six key bioclimatic variables were retained after Pearson correlation analysis and jackknife testing: mean diurnal temperature range (bio2), temperature seasonality (bio4), maximum temperature of warmest month (bio5), precipitation seasonality (bio15), precipitation of warmest quarter (bio18), and precipitation of coldest quarter (bio19); bio18 and bio5 contributed most (32% and 28.8%, respectively). Under current climate conditions, total suitable habitat covered 25.73% of China (247.47×10⁴ km²), with highly suitable areas concentrated in eastern Sichuan, Chongqing, and the coastal areas of South China. Future projections showed divergent trends among SPPs: total suitable area expanded under SSP1-2.6 and SSP2-4.5 (notably in the 2050s and 2070s), declined then increased under SSP3-7.0, and contracted steadily under SSP5-8.5 (a 17.87% decrease by the 2090s). The current geographical centroid of suitability was located in Tongren, Guizhou (108.326°E, 28.399°N) and is projected to shift northward and eastward. These findings provide a quantitative foundation for targeted monitoring, early warning, and region-specific management of B. diaphora under future climate scenarios.