Predicting high-risk zones for pine wood nematodes invasion: Integrating climate suitability, host availability, and vector dominance.

Pine wood nematodes (PWN, Bursaphelenchus xylophilus) cause widespread mortality in pine forests via pine wilt disease (PWD). The rapid death of diseased trees, which destroys biodiversity and significantly affects forest carbon storage, leading to negative environmental and economic consequences, as forests are crucial to the global carbon cycle. The interactions among PWN, hosts, and vector insects are closely linked to climate change. Climate warming has exacerbated changes in the geographic distribution of host tree species and vector insects, thereby increasing the rate and extent of PWD transmission. These interactions increase the risk of pine infection and can have far-reaching consequences for the health and stability of entire forest ecosystems. However, the global effects of climate change on these interactions are poorly understood. To fill this research gap and predict the potential impacts of climate change on the distribution of PWNs and vector insects in pine forests, we used the biomod2 integrated model to forecast their potential geographic distributions by 2050, 2070, and 2090 under three greenhouse gas emission scenarios (SSP126, SSP245, and SSP585). We analysed vector dominance and risk zones and found that potentially suitable areas for PWNs could migrate to higher latitudes in the future. The dominant vector insects, Monochamus alternatus, Monochamus carolinensis, and Monochamus saltuarius, exhibited a high ecological niche similarity to PWNs and their populations should be controlled. Additionally, high-risk areas for abiotic factors (environmental similarity) and biotic factors (hosts and vectors) will greatly expand in North America and Europe. Areas already infested by PWN will become high-risk zones for the conversion of carbon sinks to carbon sources. The modeled changes in the spatial and temporal patterns of PWN, hosts, and vector insects in this study provide a reference for developing management and conservation strategies for ensuring PWN control and improving future forest health.