Citrus Longhorn Beetle, Anoplophora Chinensis: An Invasive Pest in Europe

Citrus longhorn beetle (CLB), Anoplophora chinensis, is an invasive pest that is extremely damaging to a wide range of broadleaved trees and shrubs. The larvae feed within trees on the pith and vascular systems of both the lower trunks and roots. Larval development can take one to two years in the native range of the beetle, but in the UK, the lifecycle is likely to be at least two years, and more likely three to four years as has been recorded in the Netherlands. This lifecycle makes citrus longhorn beetle very difficult to detect during phytosanitary inspections and their position within the tree trunk gives the larvae protection from foliar insecticide treatments and most predators. The large and often numerous feeding tunnels created by the larvae render the trees susceptible to diseases and wind damage. If pest populations are allowed to build up, the structurally damaged trees pose a threat to people and property. Adults cause more limited damage by feeding on foliage and bark. Citrus longhorn beetle is a quarantine pest for the European Union which means that it is listed in the EU Plant Health Directive (2000/29/EC) as a harmful organism whose introduction into all Member States is banned. The natural range of CLB includes China, Japan and countries in South East Asia, but beetles have been moved around the world via traded plants, mainly in ornamental trees from Asia. Citrus longhorn beetles have been intercepted in the UK at plant nurseries, bonsai importers and in private gardens on trees and bonsais imported from China, Japan and South Korea. This pest has most commonly been found on or associated with imported maples, especially Acer palmatum (Japanese maple) from China.