Powell B E, Brightwell R J, Silverman J
Department of Entomology, North Carolina State University, Box 7613, Raleigh NC 27695-7613, USA.
Environ Entomol. 2009 Dec;38(6):1618-25. doi: 10.1603/022.038.0614.
Invasive ants often enter into facultative mutualisms that frequently lead to outbreaks of the hemipteran partner. Native ants may also enter into similar mutualisms but often these do not lead to outbreaks. However, field studies comparing the impact of an invasive and native ant on a honeydew-producing hemipteran are lacking. We monitored numerical changes of the black citrus aphid, Toxoptera aurantii, tended by adjacent colonies of the invasive Argentine ant, Linepithema humile, and the endemic odorous house ant, Tapinoma sessile, during 2005, 2006, and 2007. Ant-tended aphid numbers were higher than those of untended aphids, with L. humile-tended and T. sessile-tended T. aurantii populations being comparable in 2005 and 2007. However, in 2006, a severe storm, with heavy rainfall, reduced T. sessile and aphid populations in areas occupied by T. sessile, whereas L. humile and aphids tended by L. humile were not reduced. This suggested that T. sessile foraging activity and hemipteran-tending was negatively impacted by severe weather. A laboratory experiment simulating rainfall striking the surface of a leaf showed that T. sessile foraging activity declined sharply under severe simulated rainfall conditions, whereas foraging activity of L. humile did not. Maintaining populations of honeydew-producing Hemiptera across broad climatic conditions may be one mechanism by which L. humile gains a competitive advantage over native ants occupying overlapping niches.
入侵蚂蚁常常形成兼性互利共生关系，这往往会导致半翅目伙伴的种群爆发。本地蚂蚁也可能形成类似的互利共生关系，但通常不会导致种群爆发。然而，目前缺乏实地研究来比较入侵蚂蚁和本地蚂蚁对产蜜露半翅目昆虫的影响。我们在2005年、2006年和2007年监测了由入侵的阿根廷蚁Linepithema humile和本地的褐蚁Tapinoma sessile相邻蚁群照料的黑柑橘蚜Toxoptera aurantii的数量变化。有蚂蚁照料的蚜虫数量高于没有蚂蚁照料的蚜虫，2005年和2007年，由阿根廷蚁照料和由褐蚁照料的黑柑橘蚜种群数量相当。然而，在2006年，一场伴有暴雨的严重风暴减少了褐蚁及其所占据区域内的蚜虫数量，而阿根廷蚁及其照料的蚜虫数量并未减少。这表明恶劣天气对褐蚁的觅食活动和照料半翅目昆虫的行为产生了负面影响。一项模拟降雨撞击叶片表面的实验室实验表明，在严重的模拟降雨条件下，褐蚁的觅食活动急剧下降，而阿根廷蚁的觅食活动则没有。在广泛的气候条件下维持产蜜露半翅目的种群数量可能是阿根廷蚁相对于占据重叠生态位的本地蚂蚁获得竞争优势的一种机制。
