Invasive ants not dying out, just moving on
A recent report that Argentine ant populations are dying out is doubtful, and potentially misleading, according to scientists from Landcare Research.
Thursday 08 Dec 2011
Searching for Argentine ants
A recent report that Argentine ant populations are dying out is doubtful, and potentially misleading, according to scientists from Landcare Research.
Researcher Darren Ward says the most likely explanation for their ‘disappearance’ from surveyed sites is that they have simply moved out of the area.
“We know from studies of Argentine ants that nests and trails frequently move location because of changes in microclimates. In winter nests even combine and ‘move-in’ together, while in summer they move out across the landscape,” Dr Ward says.
Dr Ward says it is also likely that the researchers missed finding Argentine ants at some sites in the Victoria University study because human ability to detect ant populations is far lower than previously thought.
“In a paper recently submitted to the scientific journal ‘Biological Invasions’ we show there is only a 50-60% chance of finding them using current methods,” he says.
Other factors could also help explain the ‘disappearance’ of Argentine ants.
“Pest control companies and/or home owners will have already removed ants from some sites. Greater public awareness through local and regional council education programmes and more control products in the market-place means that control of populations is increasing.”
Dr Ward says the notion that if we wait 1-2 decades the ants will naturally disappear is dangerous and not supported by current knowledge of invasive ants in New Zealand or other countries. It is essential that the important on-going work by many around the country to control them continues, he says.
As well as being a household pest, Argentine ants are predicted to cause serious environmental harm on offshore islands and coastal habitats in the upper North Island. Many of these places are already fragile ecosystems, and/or are the subject of restoration and recovery attempts.
“Invasive ants will be an on-going problem for New Zealand and we cannot afford to be complacent or allow the good work to limit their impacts to date to be undone.”