Orthotomicus erosus

Mediterranean Pine Engraver Beetle - Orthotomicus erosus Wollaston
 

Gallery

Gallery with larvae

Dead tree

Mediterranean Pine Engraver Beetle
In summer 2004 it was discovered that the Mediterranean pine engraver beetle had become established in the southern Central Valley of California. The first detections occurred at two sites near Fresno (Penrose, Lee, and Seybold 2006 pers. comm.; New Pest Advisory Group, hereafter NPAG). The full extent of the infestation is still unclear, but the beetle is present in portions of at least five counties in the southern Central Valley - Kern, Tulare, Fresno and Madera counties, with additional detections in San Luis Obispo, and Monterey counties and a single beetle at the Port of Sacramento (Yolo County). No beetles have been collected at the Los Angeles County site since a single beetle was collected in 2004. (Penrose, Lee, and Seybold 2006 pers. comm.).

Introduction of the Mediterranean pine engraver beetle was not surprising, as it has been commonly associated with wood packaging. Between 1985 and 2000, a total of 385 interceptions were made by port inspectors, associated with cargo from at least 19 different countries (Haack 2004). Most originated from Spain (124 interceptions) and Italy (119). The beetle was most commonly found in crating that was associated with imported tiles, marble, and granite (Haack 2004). Shippers in Italy often failed to comply with APHIS' 1995 regulations requiring that wood packaging be stripped of bark ( Campbell & Schlarbaum, 2002).

APHIS has traced the introduction most probably to an importer of tile, marble, and other construction equipment based in Fresno (NPAG). It was probably present from three to five years before it was detected (Lee et al. 2005; NPAG).

This beetle is native to Europe, the Middle East, northern Africa, and China, and has been introduced to Fiji, Chile, South Africa, and Swaziland (Lee et al. 2005; NPAG). The record is unclear as to whether it is actually established in UK, Scandinavia, and other parts of northern Europe (Penrose, Lee and Seybold 2006 pers. comm.; NPAG).

The Mediterranean pine engraver beetle is considered to be a secondary pest (that is, it attacks trees that are already stressed by some other source). The insect produces two to seven generations per year, depending on temperatures and wood quality (NPAG). Populations can build up fast, with resulting attacks on live trees (Lee et al. 2005; NPAG). In addition to direct feeding, the insect can transmit fungi, some of which might be pathogenic (Lee et al. 2005; NPAG).

The Mediterranean pine engraver beetle primarily attacks pine species (Pinus); known hosts include several species native to North America, such as Monterey pine (P. radiata) and slash pine (P. elliottii). Recent USFS studies have shown that the insect can reach sexual maturity surviving on every pine tested to date, including all of the pines in the upper Midwest, e.g., jack pine (P. banksiana), red pine (P. resinosa), and eastern white pine (P. strobus); as well as the one pine from the southeastern U.S. tested so far, loblolly pine (P. taeda) (Seybold 2006 pers. comm). Various researchers have found adult beetles feeding on Douglas-fir (Pseudotsuga menziesii), spruce (Picea), fir (Abies), and cedar species (Cedrus). They believed that reproduction occurs only on pines (Mendel & Halperin, 1982). However, USFS studies (Lee and Seybold 2006 pers. comm) have found the insect can reach maturity living on Douglas-fir, white and black spruce, and tamarack (Pseudotsuga menziesii, Picea glauca, Picea mariana, and Larix laricina respectively) but not white fir and incense cedar (Abies concolor and Calocedrus decurrens).

In California, the Mediterranean pine engraver beetle typically is found in cut logs and other debris from exotic pines (Seybold 2006 pers. comm.). Abundant overwintering populations have been found in cut logs located in parks, golf courses, and green waste recycling centers (Lee et al. 2005) along the Route 99 corridor in Fresno, Kern, and Tulare counties (NPAG). However, on a few occasions, the beetle has been observed to colonize and develop in the stems of small- to medium-sized dead trees and in branches of larger trees (Seybold 2006 pers. comm). Because of the location of the infestations, the trees attacked to date are ornamentals planted in urban settings. Most have been exotic species, but cut debris or stumps from two native California pines--Monterey pine (Pinus radiata) and California foothill pine (P. sabiniana)--have been infested in California (Seybold 2006 pers. comm). Evidence of infestation has been found on logs as small as 6 inches in diameter; stumps as small as 4 inches in diameter; on declining branches of live trees; and in the main stems of standing dead trees (Lee et al. 2005).

The Mediterranean pine engraver beetle usually infests recently fallen trees and slash, but it also attacks stressed living trees. Scientists agree that the greatest economic damage would probably occur in pine plantations established in conditions under which the trees suffer stress, particularly drought. Native forests of North American pines are also often are subject to drought and other stress factors making them vulnerable to O. erosus (Eglitis 2000; NPAG).

Areas of Mediterranean climate--California and Mexico--and the Southeastern United States are considered to have climates suitable to the insect (Eglitis 2000; NPAG; Seybold 2006 pers. comm). As noted above, pines native to both regions are hosts for the insect. Monterey pine is a narrowly endemic species listed by the World Conservation Union as endangered (Borchert 2006); and is under stress from the exotic pitch canker fungus (Fusarium moniliforme var. subglutinans Wollenw. & Reinking) (Seybold 2004, pers. comm.; NPAG).

Jack pine forests of Michigan provide crucial habitat to the endangered Kirtland's warbler (Dendroica kirtlandii); Jack pine is vulnerable to the beetle, although climatic factors might limit the beetle's activity in the upper Midwest. Federal and state agencies spend about $2.5 million annually to manage Jack pine stands for the benefit of the warbler (Hogrefe pers. comm.).

The ExFor assessment ranked the Mediterranean pine engraver beetle as posing a high risk overall (Eglitis 2000); economic damage could be "high" and environmental damage risk was classified as "medium." Risk evaluation of the species is hampered by several major uncertainties. One significant uncertainty is whether O. erosus will compete successfully against other bark beetles (Eglitis 2000). In Chile, the Mediterranean beetle could not compete against the introduced Hylurgus ligniperda (NPAG)--which has also been introduced to United States--in New York (Haack 2006). On the other hand, the Mediterranean pine engraver quickly became a major pest in Swaziland (NPAG).

The second unknown is whether the introduced beetles are carrying an exotic or narrowly established pathogenic fungus that could cause significant damage if spread by the beetle to new areas (Eglitis 2000).

The NPAG Report recommends retaining O. erosus as a reportable/actionable pest. This action is recommended as a provisional measure allowed by the international trade rules while domestic delimiting surveys are conducted. This measure will be reviewed by APHIS in conjunction with the USDA Forest Service when the survey is complete. At that time, a decision to implement an official control program should be made (Colpetzer 2006 pers. comm.).

The NPAG Report further recommends that APHIS coordinate with the US Forest Service for surveys and future policy evaluations. These studies are under the leadership of Steven J. Seybold of the USDA Forest Service, Pacific Southwest Research Station. These studies include: characterizing the biology, distribution, and chemical ecology of this new pest in California; cold hardiness and specific aspects of host selection behavior and competition with a native bark beetle (Ips pini); improving the attractant bait for the insect (very effective attractant); host range; and evaluating the fungi associated with O. erosus (Seybold 2006 pers. comm.). The results of these studies were to be evaluated after one year (NPAG) - presumably in 2006.

Based on the available information, it is likely that O. erosus currently occupies only a small proportion of its potential range in the USA.

A USDA Forest Service pest alert (Lee et al. 2005) recommends that property managers in the infested area reduce insect numbers by practicing proper sanitation--promptly destroying (chipping, burning, or burying) cut pine material and avoiding piling it near living pines. The NPAG also recommends sanitation as the most effective control. The USFS alert further calls for maintaining the health of standing trees, and using baited traps to detect population buildups quickly. Finally, people are instructed not to move firewood.

The NPAG notes that there is a high likelihood of the pest being associated with host material bearing bark.

Sources
Borchert, D. 2006. USDA APHIS PPQ CHPST PERAL. Organism Pest Risk Analysis: Risks to the Conterminous United States Associated with the Woodwasp, Sirex noctilio Fabricius, and the Symbiotic Fungus, Amylosterium areolatum (Fries: Fries) Boidin.

Campbell, F.T. and S.E. Schlarbaum 2002. Fading Forests II: Trading Away North America's Natural Heritage. The Healing Stones Foundation.

Eglitis, A. 2000. Orthotomicus erosus Wollaston. http://www.exoticforestpests.org/english/Detail.CFM?tblEntry__PestID=9. Web site accessed 24 January 2005.

Haack, RA. 2004. Orthotomicus erosus: a new pine-infesting bark beetle in the US. Newsletter of the Michigan Entomological Society. 49 (3-4): 3.

Haack, R. 2006 Exotic Bark- and Wood-boring Coleoptera in the United States: recent establishments and interceptions. Can. J. For. Res. 36:269-288.

Lee, J.C., S.L. Smith, and S.J. Seybold 2005. USDA Forest Service State and Private Forestry Pacific Southwest Region. R5-PR-016. May 2005.

Mendel, A., and J. Halperin 1982. The biology and behavior of Orthotomicus erosus in Israel. Phytoparasitica 10: 169-181.

Spears, B.M. and C. Devorshak USDA APHIS PPQ. 2005. NPAG et Report Orthotomicus erosus Wollaston: Mediterranean Pine Engraver Beetle Coleoptera/Scolytidae NPAG Chair Approval Date: July 14, 2005.

Personal Communications
Keith Colpetzer
Entomologist
USDA-APHIS-PPQ
Center for Plant Health Science and Technology
Plant Epidemiology and Risk Analysis Laboratory
1730 Varsity Drive, Ste. 300
Raleigh, NC 27606
Office 919-855-7640
Fax [phone]
kecolpet(at)aphis.usda.gov

Jana C. Lee
Chemical Ecology of Forest Insects
USDA Forest Service and UC-Davis
720 Olive Drive, Suite D,
Davis, CA 95616
Office: 530-297-7041
jctlee(at)ucdavis.edu

Richard L. Penrose
Pest Detection/Emergency Project
California Department of Food & Agriculture
1220 N Street, Rm A-330
Sacramento, California 95814
Office 916-262-1100
Fax [phone]
dpenrose(at)cdfa.ca.gov

Robert J. Rabaglia, PhD
USDA Forest Service, Forest Health Protection
1601 North Kent Street, RPC7
Arlington, VA 22209
Ph: [phone]
Fax: [phone]
email: brabaglia(at)fs.fed.us

Steven J. Seybold, Ph.D.
Chemical Ecology of Forest Insects
USDA Forest Service, Pacific Southwest Research Station
720 Olive Drive, Suite D
Davis, California 95616
Phone [phone]
Fax [phone]
sseybold(at)fs.fed.us