Gibb Heloise
Institute of Wildlife Research, School of Biological Sciences, The University of Sydney, Heydon-Laurence Building AO8, New South Wales 2006 Sydney, Australia.
Oecologia. 2003 Aug;136(4):609-15. doi: 10.1007/s00442-003-1299-z. Epub 2003 Jul 3.
Ants are thought to exert an important influence on the structure of arthropod assemblages through predation and competition. I examined the effect of a dominant ant, Iridomyrmex purpureus, on epigaeic arthropod assemblages on rock outcrops using an exclusion experiment. I compared arthropod assemblages on four replicate outcrops allocated to each of the following treatments: I. purpureus present; I. purpureus absent; I. purpureus excluded; and procedural control. Nests of I. purpureus were caged in summer 2001 and epigaeic arthropod assemblages were sampled at all sites using pitfall traps in autumn and spring 2001 and summer 2002. I also collected items from foraging workers to determine the diet of I. purpureus. Exclusion cages successfully reduced the abundance of I. purpureus workers in pitfall traps by more than 97%. Exclusion of I. purpureus did not affect the size distribution, biomass or abundance of arthropod predators or non-predatory arthropods, although the total biomass of ants was greater at sites with I. purpureus. Spider biomass, species richness, abundance and composition were also not affected by the presence of I. purpureus, although the I. purpureus mimic and specialist predator, Habronestes bradleyi, became less abundant at sites from which I. purpureus was excluded. Predation by I. purpureus on other arthropods may not have a significant effect on epigaeic arthropod communities, but the complex role of I. purpureus in this ecosystem and the high diversity of species belonging to multiple trophic levels may obscure its effects in this system.
蚂蚁被认为通过捕食和竞争对节肢动物群落结构产生重要影响。我通过一项排除实验，研究了优势蚂蚁——紫虹臭蚁（Iridomyrmex purpureus）对岩石露头地表节肢动物群落的影响。我比较了分配给以下每种处理的四个重复露头上的节肢动物群落：有紫虹臭蚁存在；无紫虹臭蚁；排除紫虹臭蚁；以及程序对照。紫虹臭蚁的巢穴于2001年夏季被圈围起来，并在2001年秋季和春季以及2002年夏季使用陷阱诱捕器在所有地点对地表节肢动物群落进行采样。我还从觅食工蚁那里收集物品，以确定紫虹臭蚁的食物。排除笼成功地使陷阱诱捕器中紫虹臭蚁工蚁的数量减少了97%以上。排除紫虹臭蚁对节肢动物捕食者或非捕食性节肢动物的大小分布、生物量或数量没有影响，尽管有紫虹臭蚁的地点蚂蚁的总生物量更大。蜘蛛的生物量、物种丰富度、数量和组成也不受紫虹臭蚁存在的影响，尽管紫虹臭蚁的拟态者和专门捕食者——布拉德利悍蚁（Habronestes bradleyi）在排除紫虹臭蚁的地点数量变少。紫虹臭蚁对其他节肢动物的捕食可能对地表节肢动物群落没有显著影响，但紫虹臭蚁在这个生态系统中的复杂作用以及属于多个营养级的物种的高度多样性可能掩盖了它在这个系统中的影响。
