Two of the world’s most invasive ants, Linepithema humile and Lasius neglectus, are destined to overlap in range as they continue to spread throughout Europe. Although L. humile arrived first, and is therefore more numerically abundant, L. neglectus is the more behaviorally dominant of the two. We performed lab trials to determine whether L. humile could use numerical abundance to overcome the behavioral dominance of L. neglectus and whether the ants’ behavioral patterns shifted when the species co-occurred. We found that L. neglectus was more aggressive when less abundant, whereas the opposite was true of L. humile. When L. neglectus was outnumbered, it employed aggressive behaviors, such as biting or chemical attacks, more frequently than L. humile; it also utilized a behavioral sequence that included mandible opening and biting. Our results for these species support the hypothesis that species modulate their behavior towards competitors, which facilitates the understanding of how multiple invasive ant species can co-occur in a given area. Moreover, our study shows that the co-occurrence of invasive species could result from the use of two strategies: (1) the Bourgeois strategy, in which aggressiveness changes based on numerical dominance and (2) the dear-enemy strategy, in which aggressiveness is reduced when competitors co-occur. Since these strategies may lead to territory partitioning, we suggest that the behavioral flexibility displayed by both species when they overlap may allow local co-occurrence and increase their likelihood of co-occurrence during their range expansion in Europe, which could have a negative cumulative impact on invaded areas.

世界上最具侵略性的两种蚂蚁，Linepithema humile和Lasius neglectus，由于它们继续在整个欧洲蔓延，注定在范围上重叠。尽管哈米尔湖首先到达，因此在数量上更为丰富，但疏忽湖狼在这两种行为上占主导地位。我们进行了实验室试验，以确定人种L. Humile是否可以利用数字丰度来克服疏忽人种L.lectlect的行为优势，以及该物种同时出现时蚂蚁的行为模式是否发生了变化。我们发现，L. neglectus更积极的时候不丰富，而相反的是真正的L. humile。什么时候疏忽乳杆菌的数量比不多，它比激进甘露草更频繁地采用攻击性行为，例如咬人或化学攻击。; 它还利用了包括下颌下颌和下颌的行为顺序。我们对这些物种的研究结果支持以下假设：物种会调节其对竞争者的行为，这有助于了解在特定区域内多种入侵性蚂蚁物种如何共生。此外，我们的研究表明，入侵物种的同时存在可能是由于两种策略的使用：（1）资产阶级策略，其中侵略性基于数值优势发生变化；（2）亲敌策略，其中侵略性竞争对手同时发生时减少。由于这些策略可能会导致区域划分，因此我们建议，两个物种在重叠时表现出的行为灵活性可能允许局部共生，并增加它们在欧洲范围扩展中共生的可能性，