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Citrus longhorn beetle - reminder

Thursday 3rd June 2010

After the harsh winter, temperatures are hotting up and gardens are blooming. Unfortunately this is also the time that some unwanted arrivals can start to emerge. Fera is asking members of the public and the horticultural trade to look out for the Citrus longhorn beetle (A.chinensis), which has been moving around the world in ornamental trees (particularly Japanese maple)imported from Asia.

The beetle is a non-native pest that can be extremely damaging to a wide range of broadleaved trees and shrubs posing a serious threat to horticulture, forestry and native trees in the UK. In other European member states outbreaks have already led to the destruction of thousands of mature trees and eradication costs running into millions of Euros. Although there are no known outbreaks of the Citrus longhorn beetle in the UK, there have been several interceptions since 2005 as well as the widespread distribution of potentially infested plants by mail order in 2008, with several findings of the beetle since then. The outbreaks in Europe and findings in the UK demonstrate that the threat from the beetle is real. An outbreak in the Boskoop area of the Netherlands in 2009/2010 was of particular concern as there is a high concentration of nurseries there supplying trees and shrubs to the rest of Europe.

Why aren't the plants inspected for presence of the pest? The easy answer to this question is that they are. Fera's Plant Health and Seeds Inspectorate (PHSI) inspect all imports from outside the EU and carry out routine surveillance checks on plants being traded in the UK. For imports, and for any other plants where the PHSI consider there is an increased risk, destructive sampling is also carried out. Unfortunately whilst the adult Citrus longhorn beetle is large and relatively easy to detect, the larvae is not as it lives and feeds inside the host, typically for one to two years across its native range (Asia) and possibly for as much as four years in Northern European climates such as the UK. This makes it very difficult to detect the pest in larval form and could result in host plants being sold on before the presence of the pest is detected. An EU suspension of imports of Japanese maple (Acer palmatum) from China (the main source of infested plants) was agreed in May 2010 in response to the findings to date.

This is why we are urging the industry and members of the public to be vigilant and to keep a look out for the pest. It is particularly important at this time of year, as May/June is when we would expect to see adult beetles beginning to emerge and spread to new hosts. July and August are when we would expect them to be at their most active. Adult beetles are large and black with variable white markings. Particularly distinctive are their antennae, which are longer than their bodies (between 1.2-2 times body length) and are black with white/light blue bands. The larval stage of the beetles is the most damaging. The larvae feed internally on the pith and vascular systems of the lower trunk and root. The tunnels created by the feeding leave trees susceptible to diseases and wind damage. The adults can cause more limited damage by feeding on foliage and eating young bark.

For further information on symptoms and identifying this pest please visit our website at: www.fera.defra.gov.uk/plants/plantHealth/pestsDiseases/clb/index.cfm

If you suspect the presence of this pest or see a beetle that you suspect to be a Citrus longhorn beetle, trap it if possible, and immediately report the finding to your local Fera Plant Health and Seeds Inspector:

Tel: 01904 465625

Email:

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Anybody finding one of these distinctive beetles should isolate the beetle (best in a sealed glass jar) and contact the Fera Plant Health and Seeds Inspectorate (PHSI). The PHSI should also be notified if there is other evidence of infestation by the Citrus longhorn beetle.