豆科作物对邻近棉田蚜虫-寄生蜂食物网结构与功能的影响

In agricultural ecosystem, the interaction of multiple natural enemies achieved the joint pest control. The farmland habitats influence the biocontrol efficiency of natural enemies, mainly through regulating the pest-natural enemy food web structure. The previous landscape investigation found that the parasitism rates of cotton aphids increased distinctly with the increase of the leguminous crops, soybean and peanut planting ratio. In this project, we focused on the cotton aphids and their parasitic natural enemies. The multiplex PCR technique will be applied to establish the quantitative aphid-primary parasitoid-hyperparasitoid food web. The questions, how the leguminous crops affect the cotton aphid-primary parasitoid-hyperparasitoid tri-trophic food web structure and how the food web structure regulates the biological control efficiency of parasitoids on cotton aphids, will be systematically illustrated at landscape and local scale respectively. The results shall provide the theoretical basis to clarify the regulation mechanism of agricultural landscape on biocontrol efficiency of aphid parasitoids and scientific evidences to develop the cotton aphids ecological control strategy centered on the rational distribution of leguminous crops.

在农田生态系统中，多种天敌共同发生、相互作用，对害虫形成联合控制作用。农田生境影响天敌的生物控害功能，其关键是调控害虫-天敌食物网的结构。项目组前期发现，随着农田景观中豆科作物——大豆和花生种植比率增加，棉田棉蚜种群的被寄生率明显提高。本项目以棉蚜及其寄生性天敌为研究对象，利用多重PCR检测技术构建棉蚜-初级寄生蜂-重寄生蜂定量食物网，分别从田块水平和景观尺度系统解析豆科作物对棉蚜-初级寄生蜂-重寄生蜂三营养级食物网结构的影响效应、棉蚜-寄生蜂食物网结构对寄生蜂控蚜功能的调控作用。研究结果将为阐明农田景观格局对棉田寄生蜂控蚜功能的调控机制提供理论基础，为发展以豆科作物合理种植为主的棉蚜生态防控策略提供科学依据。

本项目以棉蚜及其寄生蜂为研究对象，利用多重PCR检测技术构建定量棉蚜-初级寄生蜂-重寄生蜂食物网，解析并揭示了豆科作物对周边棉田蚜虫-寄生蜂食物网结构的影响以及食物网结构对棉蚜寄生蜂生物控害功能的调控作用。田块水平田间调查明确了大豆邻作可显著降低棉田蚜虫种群数量；比较分析了转基因和常规棉田蚜虫-寄生蜂食物网结构，说明了转基因种植未改变食物网结构和生物防治作用，证实了多重PCR分子检测体系在食物网结构分析中的可行性；进一步对农田景观僵蚜样品进行检测，采用结构方程模型中的路径分析得出，以豆科作物为主的小宗作物面积间接降低了重寄生作用，农田景观尺度下寄生蜂物种多样性、蚜虫-寄生蜂食物网结构共同调控寄生蜂对棉花蚜虫的生物控害服务功能。研究结果突出强调了昆虫食物网结构在农业害虫生态调控中的重要功能，为阐明农业害虫地位演替机制、创新棉花蚜虫生态调控策略提供了理论支撑和思路启迪。