With its clusters of pretty white flowers, Japanese knotweed was first introduced as an ornamental plant. But with no natural enemies in the UK it soon raged out of control, wiping out surrounding vegetation and threatening wildlife. The fast-growing plant can grow up to 13 feet tall and is so strong it can break through paving stones and tarmac.
It has been estimated that to remove all knotweed from the UK would cost several billion pounds. However scientists have identified an insect - the psyllid called Aphalara itadori - that keeps the superweed under control in its native Japan by feeding on the leaves and stunting growth.
Today the Department for the Environment, Food and Rural Affairs and the Welsh Assembly have fully approved the launch of the insect as a biological control of Japanese Knotweed following a long consultation period evaluating the release the insect in Britain.
The introduction of the insect would be the first time that "biocontrol" - the use of a natural enemy to control another pest - has been used in Europe to fight a weed.
Dick Shaw, lead researcher at the not-for-profit agricultural research organisation leading the research, Cabi, said the insect would be released in a handful of sites across the UK this spring. They looked at the superweed's natural predators - nearly 200 species of plant-eating insects and about 40 species of fungi - with the aim of finding one with an appetite for Japanese knotweed and little else.
After testing their candidates on 90 different UK plant species, including plants closely related to Japanese knotweed such as bindweeds and important crops and ornamental species, they discovered a psyllid called Aphalara itadori was the best control agent. The little insect feeds on the sap of the superweed, stunting its growth.
"This psyllid is a true knotweed specialist and our research shows that it could be a safe and effective control agent for one of our worst weeds," he said.
Let's hope that it likes eating a lot of it as there is a lot of Japanese Knotweed out there. One question to ask is do psyllid get fat?
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