外来入侵植物在入侵地常面临本地地上地下植食者取食危害，由于和本地寄主植物有着不同的生理特征和防御机制，外来植物入侵可能导致本地地上地下植食者产生新的互作关系。本申请项目前期工作发现，我国本地昆虫虾钳菜披龟甲从其原有寄主植物莲子草转移到入侵植物空心莲子草上后，与地下南方根结线虫产生互作并呈显著负相关关系，因此本地地上-地下植食者可能以空心莲子草为媒介产生新的互作关系。本申请项目拟通过温室、室内饲喂和同质园实验，首先确定空心莲子草介导的地上-地下植食者互作模式；然后揭示地上-地下植食者互作机制；最后，探讨空心莲子草介导的本地地上-地下植食者互作的生态学效应。有关结果将揭示空心莲子草介导的地上-地下植食者互作模式、机制及其生态学效应，从地上地下植食者互作这一全新的角度全面阐述空心莲子草的入侵特性和生态适应性机制，为陆生生境下空心莲子草及类似外来入侵植物的生物防治及本地物种保护提供理论和实践指导。

Exotic invasive plants always consumed by both above and belowground herbivores in their new ranges, because of different Physiological features and defense traits compared with native host plant, plant invasion may result in a novel interaction of native above and belowground herbivores. In a previous study we have found that a native aboveground beetle Cassida piperata Hope shifted its host from native plant Alternanthera sessilis to invasive plant A.philoxeroides, and had negative effects with belowground nemotade Meloidogyne incognita. This result suggests that native above and belowground herbivores may interact with each other by the mediation of A.philoxeroides, which needs further clarification. Based on this finding and using the beetle’s native congeneric host plant A.sessilis as reference, this proposal plants to: 1) further identify the above-belowground herbivores interaction mediated by invasive plant by conducting greenhouse experiment,common garden experiment and larval rearing experiment; 2) exploit the mechanisms underlying novel above-belowground interaction including the plant structure; resource allocation and plant defensive chemicals; 3) test the ecological effects of novel above-belowground herbivores interactions resulting from plant invasion and its underlying mechanisms, with monitoring the fluctuation of C.piperata and M.incognita population dynamics and plants competition. The results of this project will uncover mechanism underlying novel above-belowground herbivores interaction mediated by invasive plant and identify its ecological effects. Results of this proposal will advance our knowledge of the invasive characteristics and ecological adaptability mechanism of A. philoxeroides, and will provide valuable information for guiding biological control of terrestrial alligator weed and biological conservation of native species.