入侵害虫红脂大小蠹的寄主树种适应性机制研究

The Red Turpentine Beetle (RTB), Dendroctonus valens, native to North American, is a major exotic invasive pest in China. It is reported as a secondary pest and widely distributed in its origin, damaging at least 40 species of conifers in family Pinaceae. After being introduced into China, RTB has been found seriously attacking healthy pines, mostly Pinus tabulaeformis, and gradually spreading northward in the recently years. In 2017, we found RTB has crossed from the warm-temperature zone to the mid-temperature zone and severely invaded into Pinus sylvestris var. mongolica forest stands in the Northeast China. However, it neither spreads southward nor infests the widespread Pinus massoniana. To explain the narrow host spectrum of RTB in China, and to direct the early warning of its spreading tendencies, this program would focus on the RTB host adaption mechanism and its three key phases (orientation, recognition and reception). The main contents are as following: 1) the natural host infestation of RTB by measuring its oviposition preference for seven main pine species of China, and the relationship between host selection and plant volatile during the phase of host orientation. 2) revealing the relationship between RTB host adaption and host physical, physiological-biochemical characteristic of different hosts species during the host recognition phase. 3) studying the adaption mechanism influenced by the relations between endophyte of different host species and its intestinal microorganism. In the meanwhile, studying the temperature tolerance and adaption of RTB. Through solving the scientific problem of RTB host adaption mechanism, this program would provide scientific evidence and theoretical guidance for the effective prevention and control of RTB in China.

红脂大小蠹（RTB）在原产地北美为次期性害虫，分布广泛，危害40多种松科植物。传入我国后，严重入侵健康松树，被列入重大入侵害虫。该虫以往主要危害油松，近年来逐步向北扩散，2017年发现已从暖温带跨越至中温带，严重侵害东北樟子松；但不向南扩散，不侵害广为分布的马尾松。为解析RTB在我国寄主谱窄的现象，并预警其扩散趋势，本项目围绕RTB对寄主树种的适应性机制，从寄主适应过程中的三个关键环节（定向、识别和接受）入手，重点研究（1）RTB对主要松树种类的自然侵染情况，测定对7种主要松树的选择偏好，研究其与寄主挥发物的关系；（2）研究RTB的寄主选择与不同树种物理特征、生理生化特性的关系；（3）探究RTB的寄主适应性与其肠道微生物、不同树种内生菌群的关系和机制；同时，研究RTB的温度耐受性和适应性。通过系统揭示RTB对寄主树种的适应性机制这一重要科学问题，为有效防控该虫提供科学依据和理论指导。

红脂大小蠹（RTB）在原产地北美为次期性害虫，分布广泛，危害40多种松科植物。传入我国后，严重入侵健康松树，被列入重大入侵害虫。为解析RTB在我国寄主谱窄的现象，并预警其扩散趋势，本项目围绕RTB对寄主树种的适应性机制，从寄主适应过程中的三个关键环节（定向、识别和接受）入手，主要研究成果如下：.①在寄主选择定向阶段，明确红脂大小蠹在对寄主植物的自然选择性，在林间相对于油松更偏好产卵于樟子松；对比我国7种主要松树树种新鲜木段（樟子松、油松、马尾松、华山松、白皮松、红松和落叶松）对红脂大小蠹产卵的引诱作用，其优先选择樟子松和马尾松木段入侵产卵，其次为油松木段；明确红脂大小蠹的寄主选择行为与植物挥发物的关系，受害后寄主α-蒎烯含量显著升高，行为学测定显示3-蒈烯、β-蒎烯、月桂烯、柠檬烯对红脂大小蠹具有吸引作用。.②在寄主识别阶段，揭示红脂大小蠹倾向于选择树皮粗糙且韧皮部厚的树种。.③在寄主适应阶段，红脂大小蠹可成功在油松、马尾松、樟子松、白皮松木段中定殖并羽化出子代（按子代数量由多至少排序），明确了不同树种木段内子代红脂大小蠹成虫体重及体型差异及子代成虫腹部挥发物的差异。解析不同寄主树种内生菌与红脂大小蠹伴生菌群和肠道微生物的关系，阐明红脂大小蠹的寄主接受机制。.④对红脂大小蠹的寄主与潜在寄主进行分类：明确了最适寄主植物、可接受植物、非适宜寄主植物、可取食寄主植物、不可接受植物。.⑤研究RTB的温度耐受性和适应性，融合红脂大小蠹寄主适应性、温度耐受性及相关地理气候因素，明确其分布扩散趋势及相关机制。.通过系统揭示RTB对寄主树种的适应性机制这一重要科学问题，为有效防控该虫提供科学依据和理论指导。