Many predatory coccinellids conflict with hemipteran tending ants, because they both use hemipterans as resources. Lady beetles are important in the ecology of ants and their reciprocal relationship with hemipterans. Volatiles released by lady beetles have diverse biological significance in intraspecific communication, attraction, and aggregation. However, whether the semiochemicals from lady beetles influence the sympatric members, such as aphids and ants, is still obscure. Sugarcane aphids Melanaphis sacchari was closely associated with honeydew collecting ants and coccinellid predators. Herein, we investigated the behavioral and electrophysiological responses of M. sacchari and their attending red imported fire ants, Solenopsis invicta, to an alkaloid, 2,4,6-trimethylpyridine (TMP) from the pink-spotted lady beetle Coleomegilla maculata. The response of C. maculata to this alkaloid was also evaluated. The results showed that TMP elicited significant electroantennogram (EAG) responses in M. sacchari, S. invicta, and C. maculata. In addition, it triggered significant preference and aggregation in both C. maculata males and females at 100 μg/μL, while induced a strong avoidance in M. sacchari. It significantly decreased the digging and residing preference of S. invicta workers at high concentration, but showed certain attractiveness to workers at a lower concentration. Moreover, TMP inhibited aphid-tending efficiency of S. invicta thereby curbing the benefits to M. sacchari. The findings provide important evidence that TMP is a pheromone in C. maculata and a semiochemical to both S. invicta and M. sacchari. It may affect the mutualistic interactions between S. invicta and M. sacchari by mediating the behaviors of both species.

许多掠食性球虫与半足动物的蚂蚁相冲突，因为它们都使用半足动物作为资源。瓢虫在蚂蚁的生态及其与半足动物的互惠关系中很重要。瓢虫释放的挥发物在种内通讯，吸引和聚集中具有多种生物学意义。但是，瓢虫的化学信息素是否会影响同胞成员，例如蚜虫和蚂蚁，仍然不清楚。甘蔗蚜虫Melanaphis sacchari与蜜露收集蚂蚁和球虫捕食者密切相关。在这里，我们调查了糖精分支杆菌及其伴生的红色进口火蚁Solenopsis invicta的行为和电生理响应，到粉红色斑点的甲虫Coleomegilla maculata的生物碱2,4,6-三甲基吡啶（TMP）中。还评估了斑纹梭菌对这种生物碱的响应。结果表明，TMP引起了M. sacchari，S。invicta和C. maculata的显着的触电图（EAG）反应。此外，它以100μg/μL的浓度在Mac。Maculata雄性和雌性雄性动物中引发了显着的偏好和聚集，同时强烈诱导了M. sacchari的回避。它显着降低了S. invicta的挖掘和居住偏好。高浓度的工人，但对低浓度的工人表现出一定的吸引力。此外，TMP抑制了S. invicta的蚜虫趋向效率，从而抑制了对M. sacchari的好处。这些发现提供了重要的证据，表明TMP是C. maculata中的信息素，是S. invicta和M. sacchari的信息化学物质。它可能通过介导两个物种的行为而影响S. invicta和M. sacchari之间的相互影响。