The Government has given the go-ahead to release a non-native insect to control the spread of Japanese knotweed, the first time such an approach has been used to control an invasive plant species in Europe.
Following consultations and despite caution by wildlife groups and memories of horrific attempts to introduce non-native controls like the cane toad in Australia, DEFRA says the release could reduce the £150m annual cost of knotweed damage and remediation.
Tests on a range of plant species have suggested that the psyllid, Aphalara itadori, only attacks Japanese knotweed.
"This project is not only ground-breaking, it offers real hope that we can redress the balance," said environment minister Huw Irranca-Davies.
The insects reduce the growth of the plant rather than destroying it but any relief from knotweed's relentless spread would be welcome and remediation contractors have been looking forward to deploying it alongside other controls.
Given the previous history of problems caused by introducing control species, opposition has been remarkably light.
"This will be the first time that a non-native insect has been used to control a plant species anywhere in Europe, so this is a significant decision," said the Wildlife Trust's head of living landscape, Paul Wilkinson.
"Japanese knotweed has had a big impact on the diversity of native plant species along our rivers and streams, and where it forms large stands it increases the risks of river banks eroding when it dies back in winter. Whilst trials have discovered that the Aphalara itadori cannot survive on plants other than Japanese knotweed, we would hope that the Government will continue to take a cautious approach, which will involve thorough planning and long term monitoring of the species' impact at a small number of initial sites."
CABI has carried out extensive research with the insect and tested it on 90 plant species. It says if the first phase release is successful, it would be released and monitored at other sites.
