Supercolonies of the invasive yellow crazy ant, Anoplolepis gracilipes, on an oceanic island : Forager activity patterns, density and biomass

• Published in: Insectes sociaux Vol. 52; no. 3; pp. 266 - 273
• Main Author: ABBOTT, K. L
• Format: Journal Article
• Language: English
• Published: Basel Springer 01.08.2005
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Anoplolepis; Biological and medical sciences; Decapoda; Fundamental and applied biological sciences. Psychology; Gecarcoidea natalis; Synecology; Terrestrial ecosystems; Indian Ocean Islands; invasive ants; Insecta; Daily variation; Biomass; Formicoidea; intraspecific aggression; Crustacea; Seasonal variation; Decapoda; unicolonial population; Aculeata; Formicidae; Predatory behavior; Brachyura; Social insect; supercolony; Foraging behavior; Island; Invasive species; Geographic distribution; Arthropoda; Colony; Anoplolepis gracilipes; Population dynamics; Hymenoptera; Invertebrata; Population density; Agonistic behavior
• ISSN: 0020-1812; 1420-9098
• DOI: 10.1007/s00040-005-0800-6

Ants have the capacity to reach unusually high densities, mostly in their introduced ranges. Numerical dominance is often cited as key to the ability of exotic ants to displace native ant species, reduce the abundance of invertebrates and negatively impact upon bird, land crab and other vertebrate populations. On Christmas Island, Indian Ocean, the yellow crazy ant, Anoplolepis gracilipes (Jerdon), forms supercolonies, where extremely high densities of foraging ants have contributed to `invasional meltdown' in rainforest areas. Densities of up to 2254 foraging ants per m super(2) and a biomass of 1.85 g per m super(2) were recorded, and nest densities reached 10.5 nest entrances per m super(2). Populations of A. gracilipes can overcome and kill red endemic land crabs (Gecarcoidea natalis) over 100 times their own biomass. This is the highest recorded density of foraging ants, and adds another element to the definition of `supercolony' of unicolonial ants. This paper documents one extreme in a continuum of densities of unicolonial, invasive ant species and highlights the need to incorporate forager densities into invasive ant research.