Booms, busts and population collapses in invasive ants
- 637 Downloads
The abundance of many invasive species can vary substantially over time, with dramatic population declines and local extinctions frequently observed in a wide range of taxa. We highlight population crashes of invasive ants, which are some of the most widespread and damaging invasive animals. Population collapse or substantial declines have been observed in nearly all of the major invasive ant species including the yellow crazy ant (Anoplolepis gracilipes), Argentine ants (Linepithema humile), big-headed or coastal brown ant (Pheidole megacephala), the tropical fire ant (Solenopsis geminata), red imported fire ants (Solenopsis invicta), and the little fire ant or electric ant (Wasmannia auropunctata). These declines frequently attract little attention, especially compared with their initial invasion phase. Suggested mechanisms for population collapse include pathogens or parasites, changes in the food availability, or even long-term effects of the reproductive biology of invasive ants. A critical component of the collapses may be a reduction in the densities of the invasive ant species, which are often competitively weak in low abundance. We propose that mechanisms causing a reduction in invasive ant abundance may initiate a local extinction vortex. Declines in abundance likely reduce the invasive ant’s competitive ability, resource acquisition and defense capability. These reductions could further reduce the abundance of an invasive ant species, and so on. Management of invasive ants through the use of pesticides is expensive, potentially ecologically harmful, and can be ineffective. We argue that pesticide use may even have the potential to forestall natural population declines and collapses. We propose that in order to better manage these invasive ants, we need to understand and capitalize on features of their population dynamics that promote population collapse.
KeywordsBoom and bust Population collapse Competition Pathogens and parasites Invasive ant Invasive species extinction vortex Management
We thank two anonymous referees for providing valuable comments on this manuscript. P.J.L. was supported by a James Cook Fellowship from the Royal Society of New Zealand.
- Abbott KL, Abbott KL, Green PT et al (2014) Seasonal shifts in macronutrient preferences in supercolonies of the invasive Yellow Crazy Ant Anoplolepis gracilipes (Smith, 1857) (Hymenoptera: Formicidae) on Christmas Island, Indian Ocean. Austral Entomol 53:337–346. doi: 10.1111/aen.12081 CrossRefGoogle Scholar
- Cerda X, Arnan X, Retana J (2013) Is competition a significant hallmark of ant (Hymenoptera: Formicidae) ecology? Myrmecol News 18:131–147Google Scholar
- Gilpin ME, Soulé ME (1986) Minimum viable populations: processes of species extinction. Sinauer, SunderlandGoogle Scholar
- Haines IH, Haines JB, Cherrett JM (1994) The impact and control of the crazy ant, Anoplolepis longipes (Jerd.), in the Seychelles. In: Williams DF (ed) Exotic ants: biology, impact, and control of introduced species. Westview Press, Boulder, pp 206–218Google Scholar
- Tennant LE, Porter SD (1991) Comparison of diets of two fire ant species (Hymenoptera: Formicidae): solid and liquid components. J Entomol Sci 26:450–465Google Scholar
- Wittman SE (2014) Impacts of invasive ants on native ant communities (Hymenoptera: Formicidae). Myrmecol News 19:111–123Google Scholar