关键词: 松材线虫, 墨天牛, 共生关系, 化学信号, 杀虫剂, 靶向防控

Abstract:  The pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of the devastating forest disease known as pine wilt disease (PWD), whose transmission in nature is entirely dependent on insect vectors of the genus Monochamus. In this review, we systematically summarized the recent advances in the research on the vector carriage of PWN by these beetles, focusing on the core interactive processes between PWN and Monochamus beetles, aiming to elucidate the intricate interaction mechanisms between them. Firstly, the evolutionary formation of the symbiotic relationship between Monochamus beetles and PWN was explored, highlighting how the highly specific and synchronized life cycles of the PWN and its vector Monochamus beetles forged through long-term co-evolution, underpin the successful invasion and pathogenesis of PWN. Secondly, the processes, by which PWN aggregates and undergoes morphological transformation around the beetle galleries in response to chemical signals such as terpenes, fatty acid esters and CO₂, precisely entering and exiting the tracheal system of Monochamus beetles, was systematically outlined. Additionally, the co-adaptation mechanisms between PWN and the tracheal system of Monochamus beetles were elucidated from perspectives such as tolerance mechanisms and immune interactions. Thirdly, the role of chemical signaling molecules, represented by ascarosides, in bidirectionally regulating the synchronized development of nematodes and beetles was discussed. Lastly, the direct manipulation of Monochamus beetle behaviors, such as oviposition and feeding, by PWN was examined. Furthermore, in this review we emphasized the crucial role of microbiota in maintaining this symbiotic relationship. Associated ophiostomatoid fungi (e.g., Sporothrix sp.1) serve as a nutrient source and promote population growth via signaling molecules like palmitoleic acid, while bacterial communities exhibit dual potential functions, either acting synergistically or antagonistically. Based on these mechanisms, we outlined the future research directions, including deepening the understanding of molecular interaction mechanisms, deciphering microbial functional networks, and assessing the impact of environmental stressors. We also proposed novel targeted control strategies focusing on disrupting chemical communication and regulating the micro-ecology of microbial communities, providing a theoretical basis for the development of green and precise prevention and control measures against PWD.

Key words:  Pinewood nematode; Monochamus beetles, symbiotic relationship, insecticide, chemical signals, targeted control