Futai Kazuyoshi, Ishiguro Hideaki
Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
Ishiguro Tree Doctor Office, Suzuka 513-0012, Japan.
Biology (Basel). 2025 Apr 28;14(5):485. doi: 10.3390/biology14050485.
Pine wilt disease, caused by the nematode , poses a significant threat to pine forests worldwide. Understanding the dynamics of its spread is crucial for effective disease management. In this study, we investigated the involvement of asymptomatic carrier trees in the expansion of pine wilt disease through a series of experiments. Cage-releasing experiments revealed that sexually immature Japanese pine sawyer beetles, , feeding on healthy pine branches drops only a minimal number of nematodes (primary infection). However, sexually mature beetles, still harboring numerous nematodes, fly to weakened trees for breeding and extend their feeding activities to healthy pines around weakened trees, infecting them with nematodes and thus spreading the disease further. Inoculation experiments on field-planted black pine seedlings demonstrated that even a small number of nematodes can lead to a high occurrence of asymptomatic carrier trees. Our findings suggest that nematode infections transmitted by sexually mature beetles significantly contribute to the expansion of pine wilt damage and play a crucial role in the persistence of asymptomatic carrier trees. This conclusion is based on cage-release experiments demonstrating nematode transmission by mature beetles and inoculation experiments highlighting the conditions leading to asymptomatic carrier trees.
由线虫引起的松树萎蔫病对全球的松林构成了重大威胁。了解其传播动态对于有效的病害管理至关重要。在本研究中，我们通过一系列实验调查了无症状携带树在松树萎蔫病扩展中的作用。网笼释放实验表明，取食健康松树枝条的性未成熟日本松墨天牛仅掉落极少数量的线虫（初次感染）。然而，仍携带大量线虫的性成熟甲虫会飞向衰弱树木进行繁殖，并将取食活动扩展到衰弱树木周围的健康松树上，用线虫感染它们，从而进一步传播病害。对田间种植的黑松幼苗进行的接种实验表明，即使少量线虫也会导致无症状携带树的高发生率。我们的研究结果表明，性成熟甲虫传播的线虫感染显著促进了松树萎蔫病危害的扩展，并在无症状携带树的持续存在中发挥关键作用。这一结论基于证明成熟甲虫传播线虫的网笼释放实验以及突出导致无症状携带树产生的条件的接种实验。
