Insect could halt spread of alien weed

A tiny insect could be an effective and environment-friendly weapon against a damaging and costly invasive non-native plant, scientists have said.

Defra Ministers are seeking people’s views on proposals to release the non-native psyllid Aphalara itadori to help control Japanese knotweed (Fallopia japonica). This plant has spread across Britain since being introduced as an ornamental plant in the early nineteenth century and costs the country millions of pounds in repairs to buildings, roads and railway lines.

The government is considering an application for a licence to release the psyllid to attack the plant to reduce its vigour, thus reducing the use of chemicals and the costs of control including weedkillers and physical removal. The cost of eradication nationally using conventional methods was estimated at £1.56 billion in 2003.

If a licence is issued, it is expected that the psyllid would be released and monitored at a small number of sites initially, followed by wider release in England and Wales.

Five-years’ research by scientists at CABI has shown that Aphalara itadori is the best candidate to help control Japanese knotweed in Britain. The psyllid has been tested on 87 non-target types of plant including those closely related to Japanese knotweed as well as ornamental plants and important crops, to determine whether it will feed on other plants. The findings suggest that only a few closely-related non-native knotweeds are potential hosts in Britain.

The research has been peer-reviewed by independent scientists and the Advisory Committee on Releases to the Environment.

To find out more go to

www.defra.gov.uk/corporate/consult/japanese-knotweed/index.htm. Deadline for responses is 19 October 2009.