Citrus Long-Horned Beetle (Anoplophora chinensis)

legal bases

With the Implementing Decision 2012/138/EU (consolidated version) measures to protect the Union against the introduction into and the spread within the Community of Anoplophora chinensis were adopted, which were updated by Implementing Decision 2014/356/EU.

The Pest Citrus Longhorn Beetle

The Citrus Longhorn Beetle (Anoplophora chinensis) is a species of longhorn beetle native to East Asia (China, Korea, Japan) and regulated as a quarantine pest in the EU. The adult beetles are 2-4 cm long, shiny black with irregular light spots on the wingtips, long bluish striped antennae and grainy wingtip base. The males (antennae up to 2 times the body size) are generally smaller than the females. The beetles hatch in our latitudes from June to August. The females begin with the Eiablage 10 days after the hatching. They use their mouth parts to cut T-shaped slits in the bark of the above-ground roots or stem base. A female lays in its life up to 200 cream-white, approx. 5-6 mm long eggs individually. After one to three weeks, the cream-coloured, legless larva, approx. 5 mm long, hatches and first mines in the phloem under the bark. Later, the larvae spread into the root wood until they have reached a size of 5-6 cm. The following pupae stage lasts 4-6 weeks, after which the beetle hatches at the stem base through circular bore holes with a diameter of approx. 1-1.5 cm. The maturation-food of the adult animals takes place at leaves, petioles and the bark of young branches. Under the climatic conditions of Central Europe, the development cycle usually lasts two years.

In Europe, the beetle has been present in Italy (Lombardy) since 2000. The beetle was detected in Rome in 2008 and in Tuscany (Prato) in 2014. There have been two infested areas in Croatia since 2014 (Zadar and Zagreb districts). A few finds in Denmark, the United Kingdom, France, Germany, Switzerland and the Netherlands were eradicated.

What are the routes of introduction and how do they spread?

The greatest risk of introducing CLB is the purchase of infected plants from an infested area. Special care should be taken with imported maple trees and bonsais, which may already contain beetle larvae. Locally, the disease spreads through hatched beetles.

What is being done to prevent the introduction and spread of these?

The implementing Decision (EU) 2012/138 (amended by Decision 2014/356) lays down detailed measures to protect the EU against the introduction and spread of CLB. These include rigorous rules on the import of host plants from infected third countries as well as on movement from demarcated infested areas. In Austria, the Federal Office for Food Safety (BAES) carries out import controls on plants for the agricultural sector (visual controls, possibly destructive sampling). In addition, the plant protection services in the provinces carry out monitoring for the early detection of a possible source of infestation in Austria.

How can an infestation by the Citrus Longhorn Beetle be detected?

The way of life of the Citrus Longhorn Beetle makes it difficult to find, as it is mainly located in the root area. The first signs of infestation are often drilling chips at the base of the trunk and in the root area, which are caused by the feeding activity of the larvae, as well as circular holes in the beetle through which it drills out of the wood into the open. In Italy, up to 130 drill holes were counted on a single tree. The massive damage is caused by the feeding passages. They go deep into the wood and on the one hand reduce the stability of the trees (hollowing of the stem foot), on the other hand they interrupt the sap and nutrient transport, and the tree dies as a result. The drill holes of the beetles are also ideal entry points for wood-decomposing fungi. The ripening food of the beetles also leads to withering. Please report suspicious cases to the responsible plant protection service in your federal state.

Pictures by: https://gd.eppo.int/, M. Maspero, Fondazione Minoprio, Como (IT)

Which plants would be endangered in Austria?

The host plant spectrum potentially includes all deciduous shrubs, including fruit trees and ornamental shrubs. They are considered particularly susceptible: Maple (Acer), Apple (Malus), Pear (Pyrus), Birch (Betula), Beech (Fagus), Oak (Quercus), Alder (Alnus), Hornbeam (Carpinus), Dogwood (Cornus spp.), hazelnut (Corylus), myrtle (Lagerstroemie), poplar (Populus), plane tree (Platanus), Prunus species (cherry, apricot, plum, peach), rhododendron, Rose (Rosa), Horse Chestnut (Aesculus hippocastanum), Willow (Salix), Hawthorn (Crataegus), Elm (Ulmus), Citrus and Cotoneaster. Unlike other Anoplophora species, the Citrus Longhorn Beetle does not attack conifers.

Where can I find more information about the Citrus Longhorn Beetle (Anoplophora chinensis)?

General information of EPPO: gd.eppo.int/taxon/ANOLCN

Risk assessment of the NL: www.nvwa.nl/documenten/risicobeoordeling/plantenziekten/archief/2016m/pest-risk-analysis-anoplophora-chinensis

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