Britain calls on alien parasites to take fight to Japanese knotweed

Millions of Japanese insects are to be released into the countryside to destroy Britain's most persistent weed.

The jumping plant lice, or psyllids, will be released under a plan to eradicate Japanese knotweed. They are thought to be the best weapon against the highly invasive plant, which causes millions of pounds of damage every year.



Millions of the sap-sucking insects, which are the size of a grain of sand, will be released to attack the plant. It will be the first time a foreign species has been used in Britain to control a plant.

But the move will be controversial with many conservation groups, which fear that releasing new alien species could lead to the insect attacking native plants and damaging British wildlife.



Australia and Hawaii have suffered adverse side-effects after introducing species to control invading organisms. However, scientists who drew up the plans insist that the psyllid has been thoroughly tested against nearly 100 British plants and crops without any ill effects.

The psyllid is a natural enemy of knotweed in Japan, where the plant grows on rocky, volcanic slopes. It is now so widespread in Britain that it would cost about £1.6 billion to control with conventional methods, such as herbicides.