Japanese bug to be set loose on galloping plant pest

TINY sap-sucking bugs from Japan are to be let loose in the UK to try to tackle one of the country's most problematic plants.

Rampant Japanese knotweed is so invasive it costs 150 million a year to try to keep under control.

Now a bug that feeds on the plant in Japan is to be released at two secret trial sites in the UK to find out whether they can help kill off the invader.

As revealed by The Scotsman, researchers spent five years trying to find an insect that fed on the plant, but that would not cause problems if released into the wild.

Now Defra has given permission for a psyllid called Aphalara itadori to be set loose.

This is the first time in Europe that an insect has been used to help control the spread of a non-native invasive plant.

Letting species from other countries into the environment can be risky in case it produces unexpected results.

In Australia the huge cane toad was famously released to try to control beetles in sugar cane plantations. The toads now exist in their millions and threaten many native species of wildlife.

However, experts say the behaviour of the psyllid bugs have been scrutinised so thoroughly there is little risk of anything going wrong.

The insect has been tested on more than 90 other plants, including those closely related to Japanese knotweed and important crops, to see whether it would feed on them.

The research suggests the psyllid would target only Japanese knotweed and a few other non- native species if it were released in the UK. It will be intensively monitored for several months and if successful the trial will be rolled out to other locations.

Wildlife minister Huw Irranca-Davies said: "Japanese knotweed causes over 150m worth of damage and disruption throughout the UK every year.

"This project offers real hope that we can redress the balance."

Japanese knotweed grows at up to a metre a month and can damage buildings, roads, railways and drains, as well as eroding river banks, destroying natural habitat and crowding out native plants.

It was introduced as an ornamental plant into gardens in the early 19th century and escaped into the countryside where it has no natural enemies.

Dr Dick Shaw, lead researcher on the project from specialist firm Cabi, said: "This is a great opportunity for the UK to benefit from a technique commonly used outside Europe.

"We have every reason to believe that this knotweed specialist can help limit the impacts of this weed safely and sustainably."