The fight against an aggressive super-weed could be solved by an unlikely hero – a tiny Japanese insect
It currently costs £150m a year to control and clear Japanese knotweed, a plant that grows at more than a metre a month, swamping any other vegetation in its path.
But scientists believe that a natural predator in the weed’s native home could help to solve the problem.
The trial release of the insects will be the first time that biocontrol – the use of a natural predator to control a pest – has been used in the EU to fight a weed.
First introduced to the UK by the Victorians as an ornamental plant, Knotweed soon escaped from gardens and has now spread across the UK. Incredibly tough, it can burst through tarmac and concrete, damaging roads and pavements.
In Japan, however, the weed does not rage out of control in the same way as it does in the UK. This is because it is kept in check by Aphalara itadori, a 2mm-long brown psyllid that feeds on the sap of the super-weed, stunting its growth.
Crucially, the insect is a specific agent and is believed to only feed on knotweeds. The UK government has now given the go-ahead for release of Aphalara itadori in a handful of isolated sites across England. The site will also have UK species that are closely related to Japanese knotweed planted there to check that the psyllid only targets the invasive species.
Some critics, however, are less than convinced. They say that it is impossible to be certain that the insect will only target Japanese Knotweed and could attack other species once in the wild.