There is a long history of humans either intentionally or accidentally moving plant species to areas outside of their native ranges. In novel environments, populations of many of these plant species exhibit explosive population growth and spread, in part due to the absence of coevolved enemies such as herbivorous insects. However, over time such enemies can ‘catch up' with their host and re-establish host–herbivore relationships. Though this phenomenon has been documented in several systems, little evidence exists on how this re-assembly of enemies results in increased levels of herbivory. In this study we focus on the case of black locust Robinia pseudoacacia, a sparsely populated tree species when growing on undisturbed sites in its limited native range in the eastern USA but a highly invasive species, especially in disturbed environments, in most temperate world regions. We recorded folivore damage on invasive populations in five continents, including both native and invaded portions of North America. Here, we investigated 1) how total foliage damage and damage caused by different groups of folivores differs among regions; 2) how seasonal development of folivore damage differs among regions; 3) how folivory varies with distance from the native range within North America; and 4) how the number of recorded specialist folivores correlates with the amount of folivory. We observed strong differences among regions in the amount and type of folivore damage, with the native range experiencing the highest damage, especially that caused by the native chrysomelid beetle Odontota dorsalis, which is limited to the native and invaded North American range of R. pseudoacacia. Among world regions, total folivory is negatively associated with the distance from the native range and positively associated with the number of established R. pseudoacacia specialist folivore species, supporting the hypothesis that global patterns of herbivore invasions are associated with diminished enemy release.

中文翻译：

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与入侵树上的专门食叶动物的入侵有关的敌方释放的死亡

人类有意或无意地将植物物种转移到其原生范围之外的地区有着悠久的历史。在新的环境中，许多植物物种的种群呈现出爆炸性的种群增长和扩散，部分原因是缺乏共同进化的天敌，例如食草昆虫。然而，随着时间的推移，这些天敌可以“追上”它们的宿主并重新建立宿主与食草动物的关系。尽管这种现象已在多个系统中得到记录，但很少有证据表明这种敌人的重新聚集如何导致食草动物水平增加。在这项研究中，我们重点关注刺槐刺槐的案例，刺槐是一种生长在美国东部有限的原生范围内未受干扰的地区的稀疏树种，但在世界大多数温带地区，它是一种高度入侵的物种，特别是在受干扰的环境中。我们记录了五大洲入侵种群的叶植物损害，包括北美的本土和入侵部分。在这里，我们研究了 1) 总叶子损害和不同食叶动物类群造成的损害在不同地区有何不同； 2) 不同地区叶植物损害的季节性发展有何不同； 3）叶状植物如何随着距北美本土分布范围的距离而变化； 4) 记录的专业食叶动物数量与食叶数量之间的关系。我们观察到，不同地区的叶食动物损害的数量和类型存在很大差异，其中本地范围遭受的损害最高，尤其是由本地叶甲虫Odontota dorsalis造成的损害，这种损害仅限于刺槐的本地和入侵的北美范围。 。在世界各地区中，总叶数与距原生地的距离呈负相关，与已建立的刺槐专科叶食物种的数量呈正相关，这支持了全球草食动物入侵模式与天敌释放减少相关的假设。