Lach Lori
Cornell University, Ecology and Evolutionary Biology, Corson Hall, Ithaca, New York 14853, USA.
Ecology. 2007 Aug;88(8):1994-2004. doi: 10.1890/06-1767.1.
The loss of biodiversity and associated ecosystem services are major threats posed by the spread of alien invasive species. Invasive ants are frequently associated with declines in the diversity of ground-dwelling arthropods but also may affect plants through their attraction to floral nectar and tending of hemipterans. Protea nitida is a tree native to the South African fynbos that hosts a native membracid, Beaufortiana sp., which is tended by ants. Here I compare Argentine ants (Linepithema humile) to native ants in their attraction to P. nitida inflorescences in the presence and absence of the membracid, and their effects on other floral arthropod visitors, seed set, and ovule predation. Argentine ant discovery of inflorescences increased at least 13-fold when membracids were present on the branch, whereas native ant discovery of inflorescences was only doubled by membracid presence at one site in one study year and was unaffected in the other three site-years. Excluding Argentine ants from inflorescences resulted in an increase in several arthropod taxa and potential pollinators; native ant exclusion had no positive effects. Thus the mutualism between Argentine ants and the membracid is facilitating pollinator deterrence by the ants. Though Argentine ants were not associated with a decline in P. nitida seed set or ovule predation, declines in generalist insect pollinators may have ramifications for the 83% of fynbos plants that are insect pollinated. Pitfall traps showed that Argentine ants were not more abundant than native ants in non-invaded sites. Focusing only on abundance on the ground and displacement of ground-dwelling arthropod fauna may lead to an underestimate of the effects of invasive ants on their adopted communities.
生物多样性丧失及相关生态系统服务功能丧失是外来入侵物种扩散造成的主要威胁。入侵蚂蚁常常与地面节肢动物多样性下降有关，但也可能通过对花蜜的吸引以及对半翅目的照料而影响植物。银叶山龙眼是一种原产于南非开普植物区系的树木，其上生活着一种本土角蝉，即博福特角蝉属物种，由蚂蚁照料。在此，我比较了阿根廷蚁（Linepithema humile）与本土蚂蚁在有角蝉和无角蝉情况下对银叶山龙眼花序的吸引力，以及它们对其他访花节肢动物、结实率和胚珠捕食的影响。当树枝上有角蝉时，阿根廷蚁发现花序的概率至少增加了13倍，而在一个研究年份的一个地点，本土蚁发现花序的概率仅因角蝉的存在而翻倍，在其他三个地点年份则未受影响。将阿根廷蚁排除在花序之外会导致几种节肢动物类群和潜在传粉者数量增加；排除本土蚁则没有积极影响。因此，阿根廷蚁与角蝉之间的互利共生关系促进了蚂蚁对传粉者的威慑作用。尽管阿根廷蚁与银叶山龙眼的结实率下降或胚珠捕食无关，但多食性昆虫传粉者数量的下降可能会对开普植物区系中83%的昆虫传粉植物产生影响。陷阱诱捕显示，在未受入侵的地点，阿根廷蚁并不比本土蚁数量更多。仅关注地面上的数量以及地面节肢动物区系的替代可能会低估入侵蚂蚁对其所处群落的影响。
