The Japan Times reports that British scientists plan to use bugs from Kyushu to stop the spread of a pesky weed introduced to Britain in the mid-19th century from Japan:

Working with colleagues at Kyushu University in Fukuoka, scientists went to 140 different sites and observed 186 different species that attack the plant. Looking at the range of insects on similar plants to the knotweed, the experts were able to establish that the bug — Aphalara itadori — is only found on the knotweed.

It sucks sap from the plant, thereby containing its growth. This can result in damaged stems and defoliation. In Japan, it is noticeable that the weed grows less extensively than the knotweed in Britain.

Scientists decided to take the bug back to Britain for further tests. They had to reject other insects that do much more damage because the risk to native species in Britain would be too high.

Dick Shaw, from CABI, said bugs were taken from knotweed on Mount Aso, near Kumamoto, and are now in quarantine in Britain, pending a decision by the government.

In the laboratories, scientists have been testing the bugs on other plants common in Britain to see if the insects also attack them. It has been found, however, that they do not have a negative effect on other plants, which means it will be much easier to win government approval for a controlled release of the insects.

Shaw hopes a decision will come soon so the bugs can be released in about a year.