Pine Wilt Disease Risk Is Determined by Water Vapor Pressure, Maximum Temperature, and Beetle Vector Distribution

Area of Science:

• Forest pathology and entomology
• Ecological modeling and risk assessment

Background:

• Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, poses a significant global threat to pine forests.
• Predicting PWD risk is challenging due to complex interactions between nematode, vector, host, and environmental factors.

Purpose of the Study:

• To identify and analyze key environmental and anthropogenic variables influencing PWD risk in China.
• To develop a predictive model for PWD occurrence using integrated multivariate analysis.

Main Methods:

• Employed a multivariate modeling framework integrating GeoDetector, eXtreme Gradient Boosting (XGBoost), and SHapley Additive exPlanations (SHAP).
• Benchmarked model performance against the Random Forest method.
• Analyzed seven environmental variables and anthropogenic factors, including distance to ports.

Main Results:

• Water vapor pressure (Vapr) was the most critical environmental factor, followed by average maximum temperature (Tmax) and beetle vector distribution (BV1).
• Synergistic interactions between Vapr, Tmax, and BV1 significantly exacerbated PWD risk.
• Distance to ports was the most influential anthropogenic variable, with high PWD risk within a 3-km radius.

Conclusions:

• High PWD risk is spatially associated with specific ranges of Vapr (2.37–2.75 kPa) and Tmax (29.3–30.8°C).
• Timber trading activities are identified as a major driver of long-distance PWD spread.
• Targeted prevention strategies should focus on high-risk environmental zones and stringent biosecurity at trading hubs.