肠道氧浓度下肠道细菌合成红脂大小蠹信息素能力的研究

The studies of gut bacteria of agricultural and forest insects are becoming hot topics, and a large amount of studies showed that the microorganisms have important ecological functions, e.g., nutrition provision, detoxification, and pheromone production. However, many insects’ guts were shown to contain no oxygen or have low oxygen tension, the function of the gut bacteria that had been verified in air oxygen surrounding may not reflect the function of the bacteria in the gut in vivo of these insects comprehensively. Dendroctonus valens LeConte is a destructive pine-killing invasive pest in China. Trapping with semiochemicals and pheromones has been deployed successfully in D. valens management in China. Although gut aerobic bacteria of the beetle have been proved to produce a pheromone in an air oxygen concentration in vitro, no studies determine oxygen concentration in the beetle’s gut so far, and the capability of pheromone production by gut bacteria in a gut-simulated oxygen environment is still unknown. In this study, we plan to systematically isolate and identify gut anaerobic and facultative bacteria of dispersing and attacking D. valens adults, and determine gut oxygen concentration, and further assay the capability of pheromones’ production by the bacteria in a gut-simulated oxygen environment. The isolated gut anaerobic and facultative bacteria strains and the assayed oxygen level of the beetle’s gut would facilitate the study of the bacterial functions including pheromone production. Besides, the results would refine our concept of the connection between gut bacteria of D. valens and its pheromone production, which may provide some clues for similar studies.

昆虫肠道细菌是当今农林昆虫研究的热点，一系列研究揭示了昆虫肠道细菌重要的生态学功能，如，改善宿主营养吸收、解毒、信息素合成等。然而，很多昆虫肠道为缺氧或微氧的环境，有氧条件下对其肠道细菌功能的研究并不全面。红脂大小蠹是严重危害我国林业的林业入侵害虫。以信息素为核心的红脂大小蠹防控关键技术，在我国阶段性的成功防控红脂大小蠹。虽然红脂大小蠹部分肠道细菌被证明可在体外有氧条件下合成信息素，但其肠道氧浓度如何，肠道细菌在肠道氧浓度条件下合成信息素能力如何等科学问题有待探讨。本项目计划在前期研究的基础之上，系统分离和鉴定红脂大小蠹肠道厌氧与兼性厌氧细菌；测量肠道氧浓度；探究肠道氧浓度下肠道细菌合成信息素的能力。研究结果可获得肠道厌氧细菌菌种资源，了解小蠹虫肠道氧含量，为肠道细菌功能研究提供基础；同时也更加全面揭示红脂大小蠹肠道细菌与信息素合成之间的关系，为相似体系的研究提供参考。

红脂大小蠹是严重危害我国林业的林业入侵害虫，前期研究表明其肠道中存在丰富的肠道菌群，但厌氧菌或兼性厌氧菌，以及肠道菌的其他功能有待进一步研究。本项目以红脂大小蠹及其肠道细菌为主要研究对象，围绕肠道细菌功能开展研究，系统回答了肠道细菌组成、以及各物种的丰富度；明确了肠道菌群在红脂大小蠹进攻寄主植物过程中与植物营养和防御物质之间的互作关系；明确肠道菌群在红脂大小蠹与病原真菌球孢白僵菌的互作过程中的作用及机制；鉴定红脂大小蠹免疫基因并揭示其与球孢白僵菌和伴生真菌长梗细帚霉的免疫互作过程，相关研究成果为丰富虫-菌互作模型提供理论基础、为研发新型复合高效生防菌剂提供参考。