Invasive 'super ant' species taking hold in the UK

Asian super an attacking an aphid on a leaf

Asian 'super ant' attacking an aphid on a leaf

8 July 2016 by Mary Goodchild

An invasion of Asian 'super ants' is taking hold faster than ever in the UK, new research has found.

Three new infestations of an invasive garden ant - first discovered here in 2010 and known for building massive colonies of tens of thousands of insects - have been found in the UK this year alone. Researchers believe there are many more sites yet to be uncovered.

There are now a total of six known UK infestations of the Lasius neglectus which thrive in green houses and domestic gardens, and are likely to have arrived in the UK through the import of exotic plants.

The ants pose no threat to humans but alien species are capable of dramatically altering ecosystems and can drive native species to extinction. It is estimated that invasive species cost the UK £1·7 billion every year through damage and management costs.

But Dr Elva Robinson at the University of York believes the true cost of the new species' impact on biodiversity could be much higher. Since 2014, Robinson has been working alongside PhD student Phillip Buckham-Bonnett to establish the extent of the invasion in the UK.

Her work has formed the basis of a Rapid Risk Assessment submitted to the government's Animal & Plant Health Agency in June. It shows an increase in the rate of new 'super ant' discoveries, offering recommendations for management on a national scale and could inform decision-making on UK biosecurity.

Ant attacking scale bug

Ant attacking scale bug

The Lasius neglectus appeared twenty years ago in Turkey and has since spread across the continent. It was first discovered in the UK at a National Trust property in Gloucestershire, where an infestation of around 35,000 was exposed in the Hidcote Manor gardens. Five years later - and 100 miles east - the ants were discovered in a London home and another site was identified in Cambridgeshire. This year, the ants have been discovered in Yorkshire and two sites on the south coast. Robinson has found no obvious connection between the sites.

Despite its name, the ant is in fact smaller than the common native UK variety. It is known as 'super' and not because of its size or aggression but because it builds 'super' colonies with many queens and interconnected nests which can stretch for miles.

Robinson says this trait allows the alien species to out-compete native ants commonly found in UK gardens. Native ants form new colonies when a queen vacates the nest and starts her own, competing for food and space with the old colony. By living in extended colonies in large numbers, the super ant is able to out-compete for aphids and space.

She said: "We think the invasive ants have the potential to have a big impact on the native ecosystem. In the sites we have studied, it is clear they are excluding the native ants. They are clearly dominating, and where they cluster native species are being pushed out. So far, they have been discovered in gardens and glass houses, but we don't yet know whether these ants will be able to thrive outside areas of human habitation."

She said it was unlikely, for example, that the invasive garden ant could out-compete the UK wood ant, but gaining a strong understanding its new place in the native habitat will help manage the situation. Her team is on the look-out for new sites in likely areas and is able to verify new sites as reported by pest control, but she says the garden ants can be difficult for members of the public to identify.

"Apart from being slightly smaller, the invasive garden ant looks a lot like our common native garden ant so they can be difficult to recognise," she said. "These new ants are not aggressive, they do not sting and they pose no harm to humans beyond people finding it unpleasant to have an infestation."

Four ants fighting

Ant fight club

At existing sites, gardeners are taking precautions to minimize the likelihood of furthering the infestation, with the National Trust at Hidcote actively supporting Dr Robinson's research and putting measures in place to minimize chance of further spread.

The ants have previously been described as 'fire ants' due to an apparent attraction to electricity, but Robinson suggested this threat may have been overstated, adding: "They do seem to be very good in getting into outdoor electrics - there was a colony in France that got into the controls for an outdoor electric gate and kept opening it up!"

The research is being a carried out thanks to funding from NERC and Hymettus, which undertakes research and provides advice on the conservation of bees, wasps, ants and other invertebrates in the British Isles.

Robinson has asked anyone who thinks they may have an infestation of the invasive garden ant to get in touch with Phillip Buckham-Bonnett at .