紫茎泽兰响应天敌昆虫取食胁迫的生理调控机制

Based on the current situation of the continuous expansion of a global serious invasive plant, Ageratina adenophora, and focused on the scientific issue that the resources reallocation between growth and defense after an exotic plant invaded into a new area; the proposed project will work on A. adenophora populaitons that from origin area (Mexico) and invaded area (China), with techniques and methods of biogeographical comparison and physiological ecology, try to answer the following three questions: (1) Influence of insect herbivory (such as the specialist herbivore Procecidochares utilis and the generalist herbivore Dorylus orientalis) on the component of insect resistance and plant tolerance between origin and invaded populations of A. adenophora; (2) Whether additive effects exist beteween specialist herbivore and generalist herbivore on A. adenophora performance inhibition, especially for the invaded populations? The research results are essential and criticle to explain how invaded A. adenophora response to the stresses of specialist herbivores, generalist herbivores and interspecific competition, and its physiological regulation mechanism. It helps to clearly interpret the dynamics of energy allocation and defense strategy evolution during the invading process of A. adenophora. These results will be helpful for further verification of whether the invasion mechanism of A. adenophora is in accordance with the "Enemy Release Hypothesis" (ERH) and the "Evolution of Increased Competitive Ability hypothesis" (EICA), and enrich and develop the “shifting defence hypothesis”(SDH), which provides the scientific basis for the coordination of natural enemies and ecological restoration by competitive replacement of A. adenophora.

基于外来恶性杂草紫茎泽兰入侵我国以来不断扩张的现状，围绕外来有害植物入侵后出现生长与防御间的资源再分配这一科学问题，本项目采用生物地理比较和生理生态技术方法，以原产地（墨西哥）和入侵地（中国）紫茎泽兰种群为对象，重点研究：（1）天敌昆虫（例如专食性天敌泽兰实蝇寄生和广食性天敌东方行军蚁取食）对原产地和入侵地紫茎泽兰抗虫物质含量和耐受性的影响；（2）专食性天敌寄生和广食性天敌昆虫取食胁迫对紫茎泽兰的抑制作用是否存在加性效应？研究结果将诠释紫茎泽兰响应专食性天敌寄生、广食性天敌取食胁迫的生理调控机制，阐明紫茎泽兰在入侵前后的能量分配与防御策略演化动态，从而在验证紫茎泽兰的入侵是否符合“天敌逃逸假说”和“增强竞争力进化假说”的同时，丰富和发展“防御转化假说”，最终为协调应用天敌昆虫防治紫茎泽兰提供科学依据。

本项目以原产地（墨西哥）和入侵地（中国）紫茎泽兰种群为对象，比较了其原产地与入侵地种群的生物量及抗虫性，研究了专食性天敌泽兰实蝇寄生和广食性昆虫棉蚜、斜纹夜蛾取食后原产地与入侵地紫茎泽兰抗虫物质含量及耐受性变化，分析了紫茎泽兰土壤有益微生物对紫茎泽兰生长的影响，探究了斜纹夜蛾取食紫茎泽兰对其生长发育和繁殖的影响，揭示了紫茎泽兰在入侵前后响应专食性天敌寄生、广食性昆虫取食胁迫的生理调控机制及其能量分配与防御演化策略，为协调应用天敌昆虫防治紫茎泽兰提供了科学依据。主要结果如下：（1）入侵地紫茎泽兰种群比原产地种群有更强的生长能力，原产地种群的单宁酸和总酚含量较高，类黄酮含量较低，说明紫茎泽兰把原来用于维持抗性的资源用于生长, 提高了竞争能力，符合 “增强竞争力的进化假说”。（2）专食性天敌泽兰实蝇的寄生显著抑制了紫茎泽兰的生长，并可能改变其生长与防御之间的能量分配，显著降低了自身的生长、营养物质和单宁酸含量，而其过氧化氢酶（CAT）、超氧化物歧化酶（SOD）、总酚和类黄酮含量却显著增加；紫茎泽兰的原产地种群具有较高的抗性和较低的耐受性，其单宁酸、总酚和淀粉含量高于入侵地种群，而类黄酮含量、总生物量却相反，符合“天敌逃逸假说”，说明其入侵前后发生了防御转化，丰富和发展了“防御转化假说”，并间接支持了“氮分配的进化假说”；紫茎泽兰的产地、泽兰实蝇寄生密度及寄生阶段均可影响紫茎泽兰的耐受性，其中产地和寄生阶段是影响紫茎泽兰丹宁酸和总酚变化的主要原因。（3）广食性昆虫棉蚜的取食可显著抑制紫茎泽兰生长，并导致其可溶性糖、可溶性蛋白、类黄酮、总酚和保护酶活性升高，单宁酸含量降低；棉蚜取食后，入侵地种群的可溶性蛋白、可溶性糖和类黄酮含量，过氧化物酶（POD）及SOD活性显著高于原产地种群，表明入侵地种群对广食性天敌昆虫的取食具有更好的耐受性；在高CO2浓度下，棉蚜取食后紫茎泽兰的可溶性糖含量显著升高，说明其耐受性增强。（4）广食性昆虫斜纹夜蛾在紫茎泽兰上可完成整个世代，对紫茎泽兰扩张有一定抑制作用，但紫茎泽兰并非斜纹夜蛾的适宜寄主，不利于其种群增殖，高CO2浓度下其取食适应性增强。（5）紫茎泽兰根际土壤有益微生物（丛枝菌根真菌、蜡状芽孢杆菌）均对紫茎泽兰的生长具有正反馈作用，有利于其入侵与扩张，支持了“互利助长假说”。