The predator-predator naïveté hypothesis suggests that non-native predators benefit from being unknown to native predators, resulting in reduced intraguild interference with native predators. This novelty advantage should depend on the ability of native predators to recognize cues of non-native predators. Here, we compared ant aggression and lady beetle reaction in four native and the invasive lady beetle species Harmonia axyridis. In addition, we tested whether lady beetle cuticular hydrocarbons (CHCs) are involved in species recognition, which might explain naïveté if the invasive species has a specific CHC profile. To this end, we conducted behavioral assays confronting two native ant species with both living lady beetles and lady beetle elytra bearing or lacking CHCs of different lady beetle species. Finally, we characterized CHC profiles of the lady beetles using GC–MS. In general, the aggression of Lasius niger was more frequent than that of Myrmica rubra and L. niger aggression was more frequent towards most native lady beetle species compared to H. axyridis. The removal of CHCs from lady beetle elytra reduced aggression of both ant species. If CHCs of respective lady beetle species were added on cue-free elytra, natural strength of L. niger aggression could be restored. CHC analyses revealed a distinct cue composition for each lady beetle species. Our experiments demonstrate that the presence of chemical cues on the surface of lady beetles contribute to the strength of ant aggression against lady beetles. Reduced aggression of L. niger towards H. axyridis and reduced avoidance behavior in H. axyridis compared to the equally voracious C. septempunctata might improve the invasive lady beetle’s access to ant-tended aphids.

捕食者-捕食者naïveté假说表明，非本地掠食者受益于本地掠食者的未知，从而减少了对本地掠食者的行会内部干扰。这种新颖性优势应取决于本地掠食者识别非本地掠食者线索的能力。在这里，我们比较了四种原生和侵入性瓢虫物种Harmonia axyridis的蚂蚁攻击和瓢虫反应。。此外，我们测试了瓢虫表皮碳氢化合物（CHC）是否参与物种识别，如果入侵物种具有特定的CHC特征，则可能解释naïveté。为此，我们针对两种活体瓢虫和瓢虫elytra携带或缺乏不同瓢虫物种的CHC的两种本土蚂蚁进行了行为分析。最后，我们使用GC-MS对瓢虫的CHC特征进行了表征。总的来说，与木本菌相比，黑松草的侵害要比Myrmica rubra的侵害更频繁，而黑曲霉对大多数本土瓢虫的侵害更频繁。。从瓢虫鞘翅目中去除CHCs可降低两种蚂蚁物种的侵略性。如果在无提示鞘翅上添加相应的瓢虫种的CHC，则可以恢复L. niger侵略性的自然强度。CHC分析显示每种瓢虫物种都有不同的提示组成。我们的实验表明，瓢虫表面上化学线索的存在有助于蚂蚁对瓢虫的侵略强度。与同样贪食的角膜锦梭菌相比，降低了黑种猪对木虱的侵略性和减少了木虱的回避行为，可能会改善侵入性瓢虫接触蚂蚁蚜虫的能力。