Climate change may make pine wilt disease more prevalent

Pine wilt disease is one of the most severe and devastating diseases affecting pine forests worldwide, resulting in huge economic losses in many countries. The pinewood nematode, Bursaphelenchus xylophilus, is the causal agent of pine wilt disease and is obligately vectored by pine sawyer beetles, of the genus Monochamus. For the disease to be present, the habitat must be suitable for the pinewood nematode, and include at least one vector species, and at least one host species. To predict its potential distribution, a model must consider all three components. However, no comprehensive study has examined the influence of climatic suitability on the distribution of this 'biological complex'. This study addresses this gap by incorporating biotic interactions, specifically involving 13 vectors and 61 host plants, into projections based on the pinewood nematode model. We predicted the global potential distribution of pine wilt disease and compared it with the pinewood nematode model to highlight the importance of including biotic interactions in species distribution models under climate change. We found that the model revealed an overall trend of increasing suitability scores for both the pinewood nematode and pine wilt disease models under future climate scenarios. Furthermore, compared to the pinewood nematode model, the biotic model results in an apparent increase in suitability worldwide in the future as the climate will be more suitable to vector and host complexes, suggesting that pine wilt disease could potentially spread to other places via available hosts and vectors.

Synthesis and applications:

By incorporating biotic interactions, we projected a more accurate suitable area for pine wilt disease, offering valuable insights into regions at high risk for future invasions by the disease and its vectors. This information supports the development of management and early detection strategies in areas of high suitability, helping to mitigate potential economic and ecological losses. Additionally, this study introduces a novel approach for integrating biotic factors into species distribution models.

松材线虫病（Pine wilt disease）是全球范围内危害松林最严重、极具破坏性的病害之一，给诸多国家造成了巨额经济损失。松材线虫（pinewood nematode, Bursaphelenchus xylophilus）是该病的病原物，其传播严格依赖墨天牛属（Monochamus）的松墨天牛（pine sawyer beetles）媒介昆虫。病害发生的必要条件是生境适宜松材线虫生存，且至少存在一种媒介物种与一种寄主物种。若要精准预测其潜在分布，模型必须涵盖这三个核心组分。然而，目前尚无综合研究探讨气候适宜性对这一"生物复合体"分布的影响。本研究填补了这一研究空白，将生物交互作用（具体包含13种媒介昆虫与61种寄主植物）纳入基于松材线虫的物种分布模型预测流程。我们预测了松材线虫病的全球潜在分布，并与仅基于松材线虫的模型进行对比，以凸显在气候变化背景下，将生物交互作用纳入物种分布模型的重要性。研究发现，在未来气候情景下，松材线虫模型与松材线虫病模型的适宜性评分均呈现整体上升趋势。进一步对比显示，相较于仅基于松材线虫的模型，纳入生物交互作用的模型在全球范围内的适宜性提升更为显著——未来气候将更适配媒介与寄主复合体，这意味着松材线虫病或可通过现有寄主与媒介进一步扩散至更多区域。

综合与应用：
通过纳入生物交互作用，我们对松材线虫病的适宜分布区进行了更为精准的预测，为识别未来该病及其媒介昆虫的高风险入侵区域提供了宝贵的参考依据。该研究结果可为高适宜区域的病害管理与早期监测策略制定提供支撑，助力减轻潜在的经济与生态损失。此外，本研究提出了一种将生物因子纳入物种分布模型的创新方法。