红火蚁与热带火蚁间的干扰竞争

【目的】为了探讨入侵火蚁在我国成功定殖及其之间的竞争机制。【方法】运用行为学方法研究红火蚁Solenopsis invicta(Buren)和热带火蚁Solenopsis geminata(Fabricius)在个体水平和群体水平上的攻击性、攻击手段及合作能力。【结果】一对一攻击试验中,红火蚁和热带火蚁之间攻击级别多集中在3级,两种入侵蚂蚁间以相互威胁为主;红火蚁大型工蚁与热带火蚁兵、工蚁间最为好斗,其攻击级别达到4级的比例最高,分别为33.04%、37.92%。热带火蚁兵蚁与各型红火蚁间攻击强度差异不显著;热带火蚁工蚁与红火蚁小型工蚁之间的攻击性最强,其攻击性(3.49)显著高于热带火蚁工蚁与红火蚁大、中型工蚁的攻击性(3.32和2.97)。在攻击手段上,3级打斗时各型红火蚁更倾向以物理攻击主动威胁热带火蚁,而热带火蚁兵、工蚁会采取多种方式主动攻击红火蚁,双方皆以躲避应对为主;4级打斗时两种火蚁主要以混合攻击为主动或应对手段。群体攻击试验显示,红火蚁群体间攻击强度和合作性会随着群体数量的增加而显著增加,热带火蚁合作性较差,其群体对抗红火蚁的优势仅仅是由于个体数量的增加。【结论】红火蚁比热带火蚁具有更强的竞争优势。研究结果为入侵蚂蚁间不对称竞争机制和长期群落替代的内在原因提供理论基础。

Interference competition between two invasive fire ants

Objectives] To explore the mechanism of interference competition between two successful invasive fire ant species, Solenopsis invicta (Buren) and Solenopsis geminata (Fabricius). Methods] A series of individual and group behavioral assays were conducted to examine the aggressive responses of these two species. Results] In individual aggression assays, aggression was mostly at level 3;workers or soldiers of both species tended to adopt threat postures rather than actually fighting. The greatest proportion of level 4 aggressive behavior was displayed by major workers of S. invicta and workers/soldiers of S. geminate (33.04%and 37.92%, respectively). Soldiers of S. geminate, and all castes of S. invicta, did not differ significantly in aggressive responses. Minor S. invicta workers and S. geminata workers had a significantly higher aggression index (3.49) than those of medium and major S. invicta workers and S. geminata workers (3.32 and 2.97, respectively), suggesting that aggression between minor S. invicta workers and S. geminata workers was more intense. Level 3 aggressive behavior, which was comprised of either physical attack, chemical attack, or both, was variable in either species. Physical attack was the first aggressive response by all S. invicta workers, whereas S. geminata employed any of the three aggressive modes at random. Either of the two species tended to avoid physical combat when they were defenders rather than aggressors. At level 4, both physical and chemical attacks were the major mode of aggression, or defense, by either species. In interspecific group aggression tests, both aggressive intensity and conspecific interactions were stronger in S. invicta than in S. geminata, and the aggressive ability of S. geminata against S. invicta increased with cumulative individual biomass, suggesting that S. invicta was competitively superior to S. geminata. Conclusion] This work lays a theoretical foundation for further study of the mechanism of interference competition and competitive displacement between these two invasive fire ant species.