Introduction of Agrilus planipennis (Emerald Ash Borer) into North America: addition to the EPPO Alert List
In June 2002, an exotic beetle was observed on dying Fraxinus trees in southeastern Michigan and was identified in July 2002 as Agrilus planipennis (Coleoptera: Bupestridae) a species of Asian origin. Significant tree mortality was reported in Michigan on Fraxinus pennsylvanica, F. americana and F. nigra. Shortly after this first finding, the pest was discovered in Ontario (Canada). In February 2003, it was also found feeding in northwestern Ohio (Lucas county). Surveys suggested that the pest has been established in southeastern Michigan for approximately 5 to 10 years, and in Ontario at least for 4 to 5 years. It is suspected that it has entered the USA at Detroit, in dunnage from cargo ships. Considering that A. planipennis was a serious threat to Fraxinus, both in urban and forested sites, phytosanitary measures are being applied in USA and Canada to prevent any further spread of the pest and, if possible, eradicate it. These measures include: restrictions on the movement of firewood of all species, and of ash nursery stock, ash trees, logs, lumber, wood, wood chips or bark chips outside the areas under quarantine. The NPPO of Sweden attracted the EPPO Secretariat’s attention to this potential new problem and suggested that A. planipennis could usefully be added to the EPPO Alert List.
Agrilus planipennis (Coleoptera: Buprestidae – Emerald Ash Borer)
Why: Agrilus planipennis is an Asian species which has recently been introduced into North America (identified in July 2002) where it causes significant damage to ash trees (Fraxinus spp.) both in urban and forest environments. Phytosanitary measures are applied in these areas to prevent any further spread of this insect. The NPPO of Sweden also suggested that this pest could usefully be added to the EPPO Alert List.
Asia: China, Japan, Korea, Mongolia, Russia (Far East), Taiwan.
North America: Canada (Ontario: Essex county), USA (Michigan: Livingston, Macomb, Oakland, Monroe, Washtenaw and Wayne counties; Ohio: Lucas county).
It is suspected that A. planipennis entered the USA at Detroit, in dunnage from cargo ships.
On which plants: So far in North America, found only on Fraxinus (forest and ornamental species): Fraxinus americana, F. chinensis, F. japonica, F. lanuginosa, F. mandshurica, F. pennsylvanica, F. nigra, F. rhynchophylla. In the literature, other woody tree species are mentioned: Ulmus davidiana var. japonica, Juglans mandshurica var. sieboldiana, Pterocarya rhoifolia, Ulmus propinqua. No data is given on the susceptibility of ash species commonly growing in Europe (e.g. F. excelsior, F. angustifolia).
Damage: Adults (7.5 to 13.5 mm long with metallic emerald green elytra) emerge between mid-May and late June in China, similar observation has been made in Michigan and Ontario. Adults feed on leaves of host trees and these become irregularly notched. Eggs are laid singly in bark crevasses. First instar-larvae bore galleries through the bark to feed on the phloem. Larvae make long serpentine galleries (up to 26-32 mm long) into the sapwood which enlarge as they grow and which are filled with brownish sawdust and frass. Full-grown larvae overwinter during one or two seasons depending on environmental conditions. Pupation takes place in the spring at the end of a tunnel near the surface. Newly emerged adults stay in the pupal chamber about 8 to 15 days and then bore D-shaped (3-4 mm diameter) exit holes on trunk and branches.
As larvae damage the vascular system, attacks of A. planipennis cause general yellowing and thinning of foliage, dying of branches, crown dieback, and eventually death of the tree after 2 to 3 years of infestation. Basal sprouting and also the presence of woodpeckers may indicate wood-boring beetle activity. After 1 to 2 years of infestation, bark often falls off in pieces from damaged trees exposing the insect galleries. In Michigan, it is estimated that A. planipennis has killed millions of trees over the past few years (F. pennsylvanica, F. americana and F. nigra, as well as several horticultural varieties of ash). In Ontario, it is estimated that it has killed 9,000 to 10,000 ash trees. A. planipennis can kill trees of various size and condition (small trees e.g. trunk of 5 cm diameter to big mature trees).
Dissemination: Adults can fly at least small distances, but further studies are needed on natural dispersion. Infested plants and wood can spread the insect over long distances.
Pathway: Plants for planting, wood, wood packing material, wood chips, firewood of Fraxinus from areas or countries where A. planipennis occurs.
Possible risks: Fraxinus species are commonly grown in the EPPO region for forestry and amenity purposes. The introduction of A. planipennis into North America show that there are pathways to disseminate this pest outside its area of origin (again wood packing material is suspected as being a risky pathway for this type of pest). Significant tree mortality has been reported in North America. Control and detection of this type of wood-boring insect is difficult. More data is needed on its potential for establishment in Europe, but considering its area of origin and the area where it has been introduced, it seems likely that if introduced, A. planipennis would be able to survive at least in some parts of the EPPO region.
EPPO RS 2003/079
Panel review date - Entry date 2003-05
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Mecteau, M.; Marchant, K. (2003) Emerald Ash Borer in Essex County, Ontario. NAPPO Newsletter, June 2003, 4-5.
Michigan State University Extension – Emerald Ash Borer and Ash Decline by Dr D.L. Roberts. http://www.msue.msu.edu/reg_se/roberts/ash/index.html
NAPPO Pest Alert. Agrilus planipennis Fairmaire 1888 – Exotic Emerald Ash Borer (EAB), Agrilus planipennis, reported in Michigan, United States and Ontario, Canada. http://www.pest.alert.org
Ohio Department of Natural Resources – Division of Forestry - Forest Health. Emerald Ash Borer. http://www.dnr.state.oh.us/forestry/health/emeraldashborer.htm
Stefan, M. (2003) Emerald Ash Borer. NAPPO Newsletter, March 2003, p 7.
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