Predicting distributional changes of Bactrocera diaphora (Hendel) (Diptera: Tephritidae) in China using an optimized MaxEnt model

Bactrocera ( Zeugodacus ) diaphora (Hendel) is a destructive quarantine fruit fly pest, and climate change may amplify its national invasion risk. Based on 83 verified occurrence records, we built an optimized MaxEnt model with an LQP feature combination and a regularization multiplier of 0.5, whose average AUC exceeded 0.96. Six bioclimatic predictors were screened after Pearson correlation analysis and jackknife testing, among which precipitation of the warmest quarter (Bio18, 32%) and maximum temperature of the warmest month (Bio5, 28.8%) dominated habitat suitability. Under present climate conditions, climatically suitable niches occupied 25.73% of China (247.47 × 10⁴ km²), mainly distributed in eastern Sichuan, Chongqing, and coastal South China. We projected future suitable ranges under four CMIP6 SSP pathways and detected divergent trends. Suitable areas expanded under low and medium-emission scenarios, fluctuated under moderate-high emissions, and shrank continuously under the highest-emission pathway with a 17.87% decrease for the period 2081–2100. The overall suitability centroid was projected to shift northward and eastward. These climate-based niche results provide a quantitative foundation for targeted monitoring, early warning, and region-specific management of B. diaphora under future climate scenarios.