First record of Saperda candida in Germany: addition to the EPPO Alert List
The NPPO of Germany recently informed the EPPO Secretariat that Saperda candida (Coleoptera: Cerambycidae) was observed for the first time on the Island of Fehmarn (Island in the Baltic Sea, part of Schleswig-Holstein). On the 2008-07-21, stems of Sorbus intermedia planted in a 30 year old avenue showed symptoms of infestation by wood boring insects. One beetle and a considerable number of circular bore holes of 9 mm diameter mainly located at the basis of the stems were observed. Fresh borings indicated that beetles had recently hatched. Living larvae were isolated from the felled trees. The beetle was identified as Saperda candida Fabricius 1787 by an entomologist Mr O. Nolte, and his result was confirmed by Dr Lingafelter, Washington (US). Within the focus zone, 18 trees out of a total of 250 trees of the avenue were felled and incinerated. An intensive monitoring programme is being carried out within a safety zone of 2 km radius around the infested trees. Similar symptoms were detected in the focus zone, on two Malus trees in a private property and on Crataegus in public green. Collected larvae are being identified by PCR. S. candida is a North-American wood boring pest of ornamental and fruit trees (Crategus, Cydonia, Malus, Prunus, Pyrus, Sorbus). The origin of its introduction into Germany is being investigated but remains unknown for the moment. This is the first time that S. candida is reported in the EPPO region.
The pest status of Saperda candida in Germany is officially declared as follows: in a limited area; Transient, actionable, under eradication.
The NPPO of Germany considered that S. candida could easily establish in Europe and that it has a high potential for damaging native trees, as a consequence the pest will be added to the EPPO Alert List.
Saperda candida (Coleoptera: Cerambycidae – round-headed apple tree borer)
Why: In summer 2008, the presence of Saperda candida was detected for the first time in Germany and in Europe. This wood boring insect was observed on the island of Fehmarn on urban trees and eradication measures were taken against it. S. candida is considered as a pest of apple trees and other tree species in North America. S. candida is a regulated pest in Quebec, Canada. Considering the risk it may present to fruit trees and ornamental trees in Europe, the NPPO of Germany suggested that it could be added to the EPPO Alert List.
Where:
EPPO region: Germany (isolated findings on urban trees, Sorbus intermedia, Malus and Crataegus, on the island of Fehmarn, under eradication).
North America: Canada (Manitoba, Nova Scotia, Ontario, Quebec, Saskatchewan), USA (reported to be present across the USA, recorded at least in Arkansas, Colorado, Florida, Georgia, Minnesota, Mississippi, Missouri, North Dakota, West Virginia).
On which plants: Malus is the preferred host plant, but S. candida also attacks Amelanchier, Aronia, Cotoneaster, Crataegus, Cydonia, Prunus, Pyrus, and Sorbus.
Damage: Adults feed on foliage but damage is caused by the larvae which attack both healthy and weakened trees. They bore galleries into the stems and trunks, preferably at the base of the trunk. Feeding damage may girdle the stems, cause dieback and eventually tree mortality (particularly on young trees). Attacked trees are more susceptible to wind breakage.
In North America, the life cycle takes 2 to 3 years to complete. Adults are light brown beetles of with two white stripes extending along the length of the body on the back. The body is 20 mm long and the antennae are at least as long. Adults are present from May/June to July, during which time they mate and females deposit eggs in slits at the base of stems. The hatched larvae begin feeding within the bark and by September, they are found between the bark and the sapwood, usually creating some sap flow at the point where they begin to feed. Larvae are whitish or yellowish (mature larvae are 20 to 45 mm long). Pupation occurs within the galleries and adults emerge in June. Populations are not synchronized so adults are produced each year.
Images can be viewed on the Internet:
http://www.barkbeetles.org/browse/getimage.cfm?imgnum=3066002
http://www.flickr.com/photos/gillesgonthier/2607652110/
http://bugguide.net/node/view/58896
http://www.pbase.com/tmurray74/image/48529356
Dissemination: There is no data on the natural spread of this insect. Over long distances, it may be transported by infested plants.
Pathway: Plants for planting of Malus and other hosts, wood?
Possible risks: Fruit trees species such as Malus, Pyrus and Prunus are widely grown across the EPPO region. Cotoneaster, Crataegus, and Sorbus are widely planted in parks and gardens for ornamental purposes and also occur in the wild. S. candida is causing problems in nurseries and young plantations. Because of the hidden behaviour of S. candida, the pest is likely to be moved undetected inside infected host plants. Control is difficult as the insect spends most of its life cycle inside the trees. Chemical control may be applied around the egg-laying period to kill adults and young larvae before they enter into the trees. In areas where the pest occurs, it is usually recommended to inspect trees for signs of infestation (e.g. sap flows, sawdust, exit holes) and kill larvae with flexible wires probed into the galleries, and also to destroy heavily infested trees. No natural enemies are reported, only woodpeckers might impact pest populations. Considering its host plants and its area of origin (present across Canada and USA), it is likely that S. candida can establish in the EPPO region. Although more information would be needed on the economic damage in North America, S. candida may be a threat for the EPPO region, more particularly to fruit trees in nurseries and young plantations.
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EPPO RS 2008/139
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Panel review date: -
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Entry date 2008-07
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Sources
Bousquet Y (ed.) (1991) Checklist of beetles of Canada and Alaska. Agriculture Canada, 430 pp.
NPPO of Germany, 2008-07.
INTERNET
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