title: Density-Dependent Effects of an Invasive Ant on a Ground-Dwelling Arthropod Community.
abstract: It is frequently assumed that an invasive species that is ecologically or economically damaging in one region, will typically be so in other environments. The Argentine ant Linepithema humile (Mayr) is listed among the world's worst invaders. It commonly displaces resident ant species where it occurs at high population densities, and may also reduce densities of other ground-dwelling arthropods. We investigated the effect of varying Argentine ant abundance on resident ant and nonant arthropod species richness and abundance in seven cities across its range in New Zealand. Pitfall traps were used to compare an invaded and uninvaded site in each city. Invaded sites were selected based on natural varying abundance of Argentine ant populations. Argentine ant density had a significant negative effect on epigaeic ant abundance and species richness, but hypogaeic ant abundance and species richness was unaffected. We observed a significant decrease in Diplopoda abundance with increasing Argentine ant abundance, while Coleoptera abundance increased. The effect on Amphipoda and Isopoda depended strongly on climate. The severity of the impact on negatively affected taxa was reduced in areas where Argentine ant densities were low. Surprisingly, Argentine ants had no effect on the abundance of the other arthropod taxa examined. Morphospecies richness for all nonant arthropod taxa was unaffected by Argentine ant abundance. Species that are established as invasive in one location therefore cannot be assumed to be invasive in other locations based on presence alone. Appropriate management decisions should reflect this knowledge.
authors: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand. Meghan.Cooling@vuw.ac.nz.
authors: M
authors: M
authors: Cooling
authors: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors: D A
authors: DA
authors: Sim
authors: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors: P J
authors: PJ
authors: Lester
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D001181:Arthropods / Q000502:physiology*; D002947:Cities; D002980:Climate; D058865:Introduced Species; D009520:New Zealand; D011156:Population Density
keywords: Linepithema humile; abundance; arthropod; density-dependence; impact