|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:
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.
Source(s) Bousquet Y (ed.) (1991) Checklist of beetles of Canada and Alaska. Agriculture Canada, 430 pp.
NPPO of Germany, 2008-07.
Becker GG (1918) The round-headed apple-tree borer Saperda candida Fab. Univ. Arkansas Agric. Exp. Stn. Bull. 146, 92 pp. http://elibrary.unm.edu/sora/Auk/v035n04/p0493-p0495.pdf
Guide d'identification des insectes adultes les plus communs au Québec. http://www.lesinsectesduquebec.com/insecta/24-coleoptera/saperda_candida.htm
Manitoba Agriculture, Food and Rural Initiatives. Round-Headed Apple Tree Borer (Saperda candida). http://www.gov.mb.ca/agriculture/crops/insects/fad82s00.html
Mississippi Entomological Museum. Cerambycidae of Mississippi by Terence L. Schiefer. http://mississippientomologicalmuseum.org.msstate.edu/Researchtaxapages/Cerambycidae%20pages/MS.Cerambycid.list.htm
Ministry of Agriculture Food and Rural Affairs. Ontario. Apple borers. http://www.omafra.gov.on.ca/english/crops/facts/apborers.htm
Missouri Nursery Pest News. http://www.mda.mo.gov/Pest/nursery/pdf/NPN_06042004.pdf
Morris RF (2002) Distribution and biological notes for some Cerambycidae (Coleoptera) occurring in the southeastern United States. Insecta Mundi 16(4), 209-213. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1552&context=insectamundi
Museum of Entomology. Florida State Collection of Arthropods Gainesville. http://www.fsca-dpi.org/Coleoptera/Mike/FloridaCerambycids/Saperda_candida.htm
Quality Tree Services. Flight Periods and Hosts of Common Shade Tree Borers in Colorado. http://www.qualitytree.org/insectinfo.pdf
Réseau d’avertissements phytosanitaires. Pépinières ornementales, no. 13, 2008-06-17 (Canada). http://www.agrireseau.qc.ca/Rap/documents/a13pep08.pdf
University of Minnesota. IPM of Midwest Landscapes. Pests of trees and shrubs. Roundheaded apple tree borer. http://www.entomology.umn.edu/cues/Web/195RoundheadedAppletreeBorer.pdf
EPPO RS 2008/139
Panel review date 2010-02 Entry date 2008-07