小圆胸小蠹及其虫菌共生体研究进展

Research advance on Euwallacea fornicatus and its fungal symbionts

小圆胸小蠹是蛀干为害的食菌小蠹,与其伴生菌构成虫菌共生体,称方胸小蠹—镰孢菌共生体,造成寄主机械损伤、枝干枯死和木材腐烂。在全球范围内寄主达63科342种,对果树、森林及城市景观等造成严重威胁,被国家林业局定为国际重大林木害虫。国外最新的分子学研究显示,方胸小蠹—镰孢菌共生体以种团形式出现,由至少5个形态上无法区分的小蠹种及其伴生菌构成,每一个小蠹种携带1或2种镰孢菌。该种团中的某些种及其伴生菌已经成为入侵物种,攻击并感染健康树木,造成了严重威胁。综述了该种团的生物学及生态学、伴生菌及寄主选择研究进展,以及食菌小蠹的控制途径,指出了我国有分布的该种分类地位急需确定,我国云南分布的该小蠹可能对我国更多地区城市阔叶树种构成威胁,对针叶树也可能构成潜在威胁。当前迫切需要在通过分子学手段澄清其分类地位基础上,深入开展种群生物学及生态学研究,以及伴生菌及寄主选择研究,揭示其成灾机制,为其有效控制提供技术支撑,以遏制其扩散蔓延的势头。

Euwallacea fornicatus is one of ambrosia beetles that colonizes tree xylem, attacking and infecting healthy trees with its phytopathogenic fungal symbionts, namely Euwallacea-Fusarium symbiosis. It causes mechanical damage to host branches and stems, leading to branch death and rotted timber. The list of attacked tree species by this beetle has increased to 342 taxa of 63 families around the world. It poses a growing threat to forest ecosystems, fruit industries, and urban landscapes. E. fornicatus was regarded as a major international forest pest by State Forestry Administration based on its devastating risk. Recent molecular studies have found that Euwallacea-Fusarium symbiosis was a complex of at least five morphologically undistinguishable species, each carrying one or two symbiotic Fusarium species. Several of those have become invasive pests around the world, attacking and infecting healthy trees due to these phytopathogenic fungal symbionts. We reviewed the research advance on the biology and ecology of this species complex including fungal symbionts and host selection, as well as current approaches for the control management of ambrosia beetle. It is urgent to find out the taxonomic status of E. fornicatus in China. E. fornicatus found in Yunnan may pose threats to urban broadleaf species in increasing number of cities and to conifers. Identification through molecular studies is now urgently needed. The biology and ecology of this pest and associated fungal symbionts and should be further studied to assess its molecular taxonomic status and better understand the mechanisms associated with pest outbreaks, thus providing technical support for pest control.