Scolytus schevyrewi (banded elm bark beetle): addition to the EPPO Alert List
Scolytus schevyrewi (Coleoptera: Scolytidae - banded elm bark beetle) is an Asian bark beetle which has recently been introduced into the USA (see EPPO RS 2005/180). Considering the fact that this species can damage Ulmus species and is suspected to transmit Dutch elm disease, the EPPO Secretariat decided to add it to the EPPO Alert List.
Scolytus schevyrewi (Coleoptera: Scolytidae) – banded elm bark beetle
Why: In 2003, the first specimens of Scolytus schevyrewi were trapped in USA in Colorado and Utah. However, it is suspected that this insect had been present for several years (in examining insect collections, it was discovered that it had been collected already in 1994 and 1998 from Colorado and New Mexico, respectively). This bark beetle of Asian origin was later found colonizing American and Siberian elms in many other states (U. americana and U. pumila). Because S. schevyrewi can damage Ulmus trees and is suspected to transmit Dutch elm disease, the EPPO Secretariat decided to add it to the EPPO Alert List.
Where:
Asia: China (Beijing, Hebei, Heilongjiang, Henan, Ningxia, Shaanxi, Xinjiang), Korea Republic, Korea DPR, Kazakhstan, Kyrgyzstan, Mongolia, Russia, Tajikistan, Turkmenistan, and Uzbekistan.
North America: USA (Arizona, California, Colorado, Idaho, Illinois, Indiana, Kansas, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, Oklahoma, Oregon, South Dakota, Utah, Wyoming).
On which plants: Ulmus species (including U. carpinifolia, U. laevis, U. minor, U. procera) are the main hosts. In Asia, S. schevyrewi is reported on forest, ornamental and fruit tree species: Ulmus spp., Caragana spp., Elaeagnus angustifolia, Salix spp., Prunus spp. (including P. armeniaca, P. dulcis, P. persica, P. salicina) and Pyrus spp. In USA, S. schevyrewi has been collected from U. americana, U. pumila, U. thomasii and U. procera, but not from any other hosts noted in the Asian literature.
Damage: Larvae feed in the inner bark. Removal of bark will reveal characteristic gallery patterns. Trunks of heavily attacked trees are often covered with brown boring dust and occasionally sap flow on the bark surface near the entrance hole. Attacked trees may also show wilting of the foliage, and branch breakage. In Asia, the severity of damage to elms is dependant on tree vigour and only weakened tree showed severe damage. Repeated attacks on declining trees can lead to tree death. In the USA, mortality of large elms, perhaps on drought-stressed trees, has been observed. The biology of S. schevyrewi is similar to that of S. multistriatus. In areas where S. schevyrewi is now well established, it is much more abundant in dying elms than is S. multistriatus. A major concern is the potential ability of S. schevyrewi to transmit Dutch elm disease (Ophiostoma ulmi or P. novo-ulmi). During studies done in 2004 in USA, it was observed that adults S. schevyrewi collected from logs cut from trees showing symptoms of Dutch elm disease were carrying spores of O. novo-ulmi (no spores of O. ulmi were found). Further studies are being done on this possible transmission.
Pictures can be viewed on Internet:
http://www.fs.fed.us/r2/fhm/reports/pest_update_s-schevyrewi.pdf
http://www.ceris.purdue.edu/napis/pests/barkb/schevy/schevyrewi_ID_new1A.pdf
http://www.colostate.edu/Depts/CoopExt/LARIMER/plantinsectid/Banded%20elm%20bark%20beetle.pdf
Dissemination: Adults are weak fliers but can spread from tree to tree. Over long distances, trade of plants for planting and wood with bark (including wood packing material) can ensure pest spread. It is suspected that S. schevyrewi has been introduced into USA in wood packaging with bark attached.
Pathway: Plants for planting, wood with bark (including wood packing material) of host species.
Possible risks: Ulmus species are valuable forest and ornamental trees in the EPPO region, which were already devastated by Dutch elm disease. Although the direct impact of S. schevyrewi and its potential role in transmitting Dutch elm disease need to be further investigated, this species could present a significant risk to elm trees in Europe. The fact that in its area of origin, S. schevyrewi is able to attack fruit tree species adds to the risk, although this feature has not been observed in the USA.
EPPO RS 2005/181
Panel review date - Entry date 2005-11
Sources
Negrón JF, Witcosky JJ, Cain RJ, LaBonte JR, Duerr DA II, McElwey SJ, Lee JC, Seybold SJ (2005) The banded elm bark beetle: a new threat to elms in North America. American Entomologist, 51(2), 84-94.
CABI Crop Protection Compendium 2005. http://www.cabicompendium.org/cpc/home.asp