The Novel Defense Hypothesis predicts that introduced plants may possess novel allelochemicals which act as a defense against native generalist enemies. Here, we aim to test if the chemicals involved in allelopathy in the invasive plant Wedelia trilobata can contribute to higher resistance against generalist herbivore and pathogen enemies by comparing with its native congener W. chinensis in controlled laboratory conditions. The allelopathic effects of the leaf extract from W. trilobata on the generalist enemies were also assessed. We showed that the larvae of two moth species preferred W. chinensis over W. trilobata. The growth rate of larvae feeding on W. trilobata leaves was significantly lower than those feeding on W. chinensis leaves. When detached leaves were inoculated with phytopathogens, the infected leaf area of W. trilobata was significantly smaller than that of W. chinensis. In addition, the leaf extract of W. trilobata also effectively inhibited the growth of the larvae and the mycelial growth of the phytopathogens. Our results indicate that the defenses of invasive W. trilobata against generalist herbivore and pathogen enemies are stronger than that of its native congener, which may be attributed to the allelopathic effects. This study provides novel insights that can comprehensively link the Novel Defense, Behavioral Constraint and Enemy Release hypotheses. These combined hypotheses would explain how invasive plants escape from their natural specialist enemies, where their allelopathic chemicals may deter herbivorous insects and inhibit pathogen infection.

中文翻译：

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化感作用赋予入侵的Wedelia更高的抵抗能力，使其比其天然同源物对普通草食动物和病原体敌人更具抵抗力。

新型防御假说预测说，引入的植物可能具有新型化感物质，可以抵御本地的多面手敌人。在这里，我们的目的是通过在受控实验室条件下与其原生同类物W. chinensis进行比较，来测试入侵植物三枝线Wedelia trilobata中与化感作用有关的化学物质是否可以提高对通配草食动物和病原体敌人的抵抗力。还评估了W. trilobata的叶提取物对通才分子的化感作用。我们表明，两个蛾类的幼虫比W. trilobata更喜欢W. chinensis。以W. trilobata叶片为食的幼虫的生长速度明显低于以W. chinensis叶片为食的幼虫的生长速度。当分离的叶子用植物病原菌接种时，感染的叶子面积为W。trilobata明显小于W.chinensis。此外，W。trilobata的叶提取物还有效抑制幼虫的生长和植物病原体的菌丝体生长。我们的结果表明，入侵性W. trilobata对普通食草动物和病原体敌人的防御能力强于其原生同类物，这可能归因于化感作用。这项研究提供了新颖的见解，可以将新的防御，行为约束和敌人释放假说全面地联系起来。这些综合的假设将解释入侵植物如何逃避其天生的专业敌人，其化感化学物质可能会阻止草食性昆虫并抑制病原体感染。三叶草还可以有效抑制幼虫的生长和植物病原菌的菌丝生长。我们的结果表明，入侵性W. trilobata对普通食草动物和病原体敌人的防御能力强于其原生同类物，这可能归因于化感作用。这项研究提供了新颖的见解，可以将新的防御，行为约束和敌人释放假说全面地联系起来。这些综合的假设将解释入侵植物如何逃避其天生的专业敌人，其化感化学物质可能会阻止草食性昆虫并抑制病原体感染。三叶草还可以有效抑制幼虫的生长和植物病原体的菌丝生长。我们的结果表明，入侵性W. trilobata对普通食草动物和病原体敌人的防御能力强于其原生同类物，这可能归因于化感作用。这项研究提供了新颖的见解，可以将新的防御，行为约束和敌人释放假说全面地联系起来。这些综合的假说将解释入侵植物如何逃脱其天生的专业敌人，其化感化学物质可能会阻止草食性昆虫并抑制病原体感染。抗普通草食动物和病原体敌人的三叶虫比其本地同类动物更强，这可能归因于化感作用。这项研究提供了新颖的见解，可以将新颖的防御，行为约束和敌人释放假说全面地联系起来。这些综合的假设将解释入侵植物如何逃避其天生的专业敌人，其化感化学物质可能会阻止草食性昆虫并抑制病原体感染。抗普通草食动物和病原体敌人的三叶虫比其本地同类动物更强，这可能归因于化感作用。这项研究提供了新颖的见解，可以将新颖的防御，行为约束和敌人释放假说全面地联系起来。这些综合的假设将解释入侵植物如何逃避其天生的专业敌人，其化感化学物质可能会阻止草食性昆虫并抑制病原体感染。