Insect may head to Swansea - 'world knotweed capital'

The insects feed on the sap of the knotweed stunting its growth

Scientists hope a tiny Japanese insect may help clean up Swansea - dubbed the "knotweed capital of the world."

A natural predator of the weed, the insect is about to be released at a handful of sites in England.

If trials go to plan, Swansea is among sites to be targeted if the Welsh Assembly Government also grants a licence - a decision is expected soon.

The weed is so hardy it can break through tarmac and concrete and costs the UK over £150m to clear and control.

In Swansea, one of the worst affected parts of Britain, its total biomass is now said to exceed 62,000 tonnes.

Japanese knotweed was first introduced to the UK as an ornamental plant in the 19th Century, but it has since spread rapidly, damaging plant biodiversity as well as hard structures, such as buildings, paving stones and flood defences.

There are sites planned in Wales - probably Swansea - it's been called the knotweed capital of the world unfortunately Dr Dick Shaw

The superweed research has been carried out by Cabi, a not-for-profit agricultural research organisation.

The team has spent several years trying to find potential candidates to control the spread of Japanese knotweed, looking for predators that feed only on knotweed and not on any of Britain's native plants.

Their chosen insect is a small psyllid called Aphalara itadori that feeds on the sap of the superweed, stunting its growth.

Dr Dick Shaw, the lead researcher, said: "[Knotweed] can rapidly get out of hand with no natural enemies of its own and the people of Wales are more aware than most of the problems it can cause.

"It's a phased release so they will be released initially at isolated locations so we can monitor it very very closely indeed.

"Hopefully if everything goes well they will be spread more widely.

"There are sites planned in Wales - probably Swansea - it's been called the knotweed capital of the world unfortunately."