外来植物与草食昆虫互作的纬度格局：地域分异及成因

草食作用和植物防御随纬度降低而增加被认为是生物地理学的一个基本格局, 即“草食作用和植物防御纬度梯度假说（LHDH）”。但近年来围绕该假说是否成立、是否具有一般性存在激烈争议。外来植物入侵常伴随草食作用和植物防御的改变，因此也是影响植物-草食昆虫互作关系纬度格局的重要因素。外来植物-草食昆虫系统可以为解决围绕LHDH假说而产生的争议提供新的思路和证据。本研究在前期工作基础上，以分布于阿根廷、中国和美国的喜旱莲子草-草食昆虫为研究系统，通过纬度梯度野外调查和同质园实验，研究草食作用-植物防御纬度格局的多样性及其影响因素。将回答两个关键问题：入侵植物-草食昆虫互作关系纬度格局在原产地和入侵地间是否出现分异？草食昆虫取食类型、食性专一性以及植物防御策略类型是否是造成这种分异的主要因素？同时在三个大陆间，采用同植物种、同生物群系、跨较大纬度梯度的"植物-草食昆虫系统"来验证LHDH假说尚未见报道。

Both herbivory and plant defenses against herbivores have been predicted to increase toward tropical regions. Early tests of this latitudinal herbivory-defense hypothesis (LHDH) were supportive, but accumulating evidence has been mixed. The invasion of exotic plants is often accompanied by the changes of herbivore and plant defense, which is also an important factor affecting the latitudinal pattern of plant- herbivore interactions. We suggest that exotic plant -herbivore systems can provide new ideas and evidence for the controversy surrounding the LHDH hypothesis. Here we test the LHDH by examining whether the pattern of herbivory and plant defense increases along the entire north-south latitudinal native (Argentina) an introduced (the United States and China) range of alligator weed (Alternanthera philoxeroide), and whether these patterns differ between native and introduced range, and whether vary with the feeding guild or degree of specialization of the herbivore species, and plant defense types.