氮素调控小麦-麦长管蚜-燕麦蚜茧蜂三级营养关系及机制

The excessive use of nitrogen fertilizer has caused serious environmental problems, which has led to the degeneration of ecosystem function. The space-time optimization technique and reduction use of nitrogen fertilizer are also hot issues in China and worldwide. In the present project, the effects of nitrogen fertilizer on three trophic relationships of wheat-aphid-parasitoid are studied according to methods of population ecology, plant-pest interaction theory, and molecular biology. First, the ecological adaptation and phenotypical plasticity of cereal aphid under different levels of nitrogen fertilizer are studied by using life table method. Then, the effects of nitrogen fertilizer on nutrition and resistance pattern of wheat are studied through integration physiology of wheat and ecological characteristics of cereal aphid, which could reveal the pattern shift of nutrition and resistance under different levels of nitrogen fertilizer. Additionally, the cereal aphid-parasitoid interaction mediated by nitrogen fertilizer is modeled, which could reveal the pattern shift of wheat physiology and resistance. The relationship between nitrogen levels and parasitism is analyzed to explore the biocontrol pattern of parasitoid in the food web. Finally, the rational optimization and utilization of nitrogen fertilizer aiming to conserve stability of food web are raised, which could be implemented to successfully conserve ecosystem services and address environmental issues related to crop pest control in agroecosystem.

近年来我国氮素过量施用引发了严重的环境问题，并造成了农业生态系统功能的整体退化，氮素减量施用和时空优化技术也是目前关注的热点问题。本项目以我国北方麦田生态系统为研究对象，以种群生态学、植物-害虫互作理论、分子生物学等理论为基础，探索氮素对小麦-麦长管蚜-燕麦蚜茧蜂三级营养关系及功能的影响。首先测定麦蚜种群在不同氮素水平下的生态适应性和表型可塑性，进而整合小麦生理学和蚜虫生物生态学过程，探索氮素对小麦营养及抗性组成的影响，研究氮素影响小麦-蚜虫互作过程的机制；然后构建氮素介导小麦营养与抗性变化调控麦蚜-寄生蜂互作过程，分析氮素水平与寄生蜂寄生率及稳定性相互作用关系，阐明麦田食物链中寄生蜂控害的作用模式。最终提出氮素减量优化合理利用和改善天敌控害功能的集成措施，同时为发展害虫生态调控理论提供新思路和新方法。

氮素过量施用已经引发了严重的生态和环境问题，并造成了农业生态系统功能的整体退化，氮素减量施用和时空优化技术也是我国农业领域的重大需求。本项目严格执行任务书的规定，以麦田昆虫群落为研究对象，以种群生态学和植物-害虫互作理论为基础，探索了氮素营养对小麦-蚜虫-寄生蜂三级营养关系及功能的影响。高氮能够驱动麦蚜种群的生态适应性和表型可塑性，导致麦蚜种群灾变；氮素主要通过调控小麦生理改变氨基酸组成有利于蚜虫取食，而对寄生蜂无显著性影响；氮素过量能够显著降低寄生蜂寄生率及稳定性，导致生态系统功能退化甚至丧失。项目不仅完成了氮素调控小麦-蚜虫-寄生蜂三级营养关系及机制，还进行了小麦混播及生理变化对麦蚜种群动态及小麦产量影响的研究，提出氮素优化施用是稳定食物网和提升生态系统功能的重要措施。项目最终提出了氮素减量优化合理利用和改善天敌控害功能的集成措施，氮素减量施用将成为将来有效控制麦蚜的有效手段。