Biogeography of Bursaphelenchus Species Driven by Climate, Vectors and Hosts: Implications for Forest Pathology Under Climate Change

Wood‐inhabiting nematodes of the genus Bursaphelenchus are a group with significant ecological and economic impacts on global forest ecosystems. This review aims to update current knowledge on their spatial distribution, host‐vector associations and the factors driving species expansion under the framework of climate change. Spatial analysis reveals that while the majority of records are concentrated between latitudes 30° N and 50° N, noting that while Europe shows the highest number of records due to intensive research on the invasive B. xylophilus , high‐latitude regions such as Siberia and the Scandinavian Peninsula exhibit low nematode occurrence despite extensive conifer coverage, suggesting that climatic thresholds act as primary limiting factors. The findings accord with the fact that the genus is predominantly associated with temperate and humid climates, with reproductive activity and development being strongly temperature‐dependent, typically requiring ambient temperature above 20°C for optimal development. A total of 77 nematode species were identified in coniferous hosts and 45 in deciduous hosts. The highest number of nematode species was recorded in Pinus sylvestris for coniferous hosts and Populus tremula for deciduous ones, highlighting their roles as key hosts in forest ecosystems. Although conifer‐associated species such as B. xylophilus and B. mucronatus dominate current records, this study highlights the significant diversity and adaptability of numerous taxa within broadleaved ecosystems. Three key drivers are identified as primary factors for shifts in spatial distribution: climate change, which facilitates poleward expansion; vector switching, a proven ecological mechanism allowing nematodes to utilize new insect hosts; and international trade, which serves as the principal pathway for introducing both nematodes and their insect vectors into novel ecosystems. The review concludes that significant knowledge gaps remain regarding Bursaphelenchus biodiversity in deciduous forests and the specific insect vectors for many species have yet to be identified. Consequently, an interdisciplinary approach is essential to improve biosecurity measures. This approach should combine molecular biology, ecological network analysis and risk modelling to mitigate future ecological impacts in a warming world.