Conservation of the Tansy beetle
The rare Tansy beetle, one of Britain's most endangered insect species is only found at one location in the UK - along 45 kilometres of the River Ouse near York.
The Tansy beetle (Chrysolina graminis) is a beautiful, iridescent green leaf beetle, about the size of a small finger nail (c.10 mm). The common name derives from the Tansy plant on which they often feed. It is also known locally as the Jewel of York.
In Britain the range of the Tansy beetle is restricted, and populations are confined to a 45km length of riverbank on the River Ouse in North Yorkshire. The beetle is endangered not only here but across its worldwide range.
Tansy beetle distribution is determined by the distribution of its main food plant. As Tansy clumps disappear due to competition from invasive plants such as Himalayan Balsam, the beetle must find new clumps by walking, as it does not fly. One problem is that beetles cannot detect their highly aromatic food plant even when they are very close! The University of York has found that, as a result, Tansy beetles only flourish when clumps are relatively large (about six square metres) and are less than about 200 metres apart.
Thanks to funding from the SITA Trust, a Tansy beetle action group has been able to initiate and complete a North Yorkshire conservation project. The project has brought together volunteers, scientists, conservation bodies, and countryside staff in a three year exercise which has cleared Himalayan Balsam and coppiced willow from 11 sites along the Ouse between Beningbrough and Riccall, planted new tansy, and provided protection to prevent grazing cattle from eating it - thereby leaving it available to the beetles.
This co-ordinated approach to practical aspects of the beetle's conservation and future monitoring will show which interventions have worked and which have not. This is critically important to an understanding of the most cost-effective ways to ensure the species' survival in Britain.
A total of 260 volunteer days have been devoted to the project since its inception in 2009 and its completion in December 2012.