Orthotomicus erosus

Name:   Orthotomicus erosus
Pest Authorities:  (Wollaston)
Taxonomic Position:  Insecta: Coleoptera: Scolytidae
Sub-specific Taxon:  
Pest Type:   Insect
Common Name(s):
   Bostrico corroso (Italian)
   Mediterranean pine engraver beetle (English)
   Sudeuropäischer Kiefernborkenkäfer (German)
   Bostrichus duplicatus Ferrari
   Bostrichus laricis Perris
   Ips erosus (Wollaston)
   Ips erosus var. robustus Knotek
   Tomicus erosus Wollaston
   Tomicus rectangulus Eichoff
Numerical Score:  9
Relative Risk Rating:  Very High Risk
Uncertainty:   Very Uncertain
Uncertainty in this assessment results from: Although adaptable, the potential competitive ability of Orthotomicus erosus in North America is not clear. This insect was introduced into Chile ca. 1986, but was either not successful in competing with Hylurgus ligniperda, another introduced bark beetle, or unable to adapt to Pinus radiata. Therefore, it is now difficult to find O. erosus in Chile. A number of species of Ips are found throughout North American conifer forests and how this insect would compete with these insects, or other bark beetles, is not known.

Establishment Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Organism has successfully established in location(s) outside its native distribution
  • Suitable climatic conditions and suitable host material coincide with ports of entry or major destinations.
  • Organism has demonstrated ability to utilize new hosts
  • Organism has active, directed host searching capability or is vectored by an organism with directed, host searching capability.
  • Organism has high inoculum potential or high likelihood of reproducing after entry.
Justification: Orthotomicus erosus is capable of infesting many species of pines. Its successful introduction into five other countries illustrates its ability to adapt to new hosts. Chararas (1973) reported that in Turkey, O. erosus was reared on a variety of hosts, including several North American pines.

A Mediterranean climate is most favorable for this insect. As such, Orthotomicus erosus could be most successful in establishing itself in portions of California and Mexico. It is also likely that this insect would be unable to establish itself in the humid southeastern US, the northern U.S. and most or all of Canada.

Spread Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Organism has demonstrated the ability for redistribution through human-assisted transport.
  • Organism has a high reproductive potential
  • Potential hosts have contiguous distribution.
  • Newly established populations may go undetected for many years due to cryptic nature, concealed activity, slow development of damage symptoms, or misdiagnosis.
  • Organism has broad host range.
Justification: Orthotomicus erosus adults are strong fliers capable of covering several km in search of suitable host material. They are also subject to dispersal by air currents. This insect is commonly associated with recently killed pines (Mendel and Halperin 1982). A wide host range and multiple generations throughout much of its natural range leads to a high likelihood of its transportation in crating material or other raw materials that contain bark. Numerous interceptions of O. erosus in United States ports since the ban of bark from packing material indicates that this is a common occurrence. Between 1985 to 2000, O. erosus was the second most commonly intercepted bark beetle at United States ports and was intercepted 385 times in wood packing material from 19 countries (Haack 2001). Newly established populations could go undetected for long periods because of its cryptic nature and similarity in appearance and habits to indigenous species of Ips. This would make eradication techniques difficult, if not impossible, to implement. O. erosus is capable of attacking a large number of pine species and would find at least some North American pines to be suitable host material.

Economic Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Organism attacks hosts or products with significant commercial value (such as for timber, pulp, or wood products.
  • Organism directly causes tree mortality or predisposes host to mortality by other organisms.
  • Damage by organism causes a decrease in value of the host affected, for instance, by lowering its market price, increasing cost of production, maintenance, or mitigation, or reducing value of property where it is located.
  • Organism may cause loss of markets (domestic or foreign) due to presence and quarantine significant status.
  • Organism has potential to be a more efficient vector of a native or introduced pest.
Justification: Orthotomicus erosus is capable of killing trees under stress, especially moisture stress. Its greatest significance would be in areas where plantations have been established under conditions that are not always favorable and in natural forests where drought and other stress factors are common. Many North American pine forests occur under these conditions including much of the important pine growing regions in the western United States and Mexico. Economic losses due to tree mortality will vary based on location and degree of tree stress.

Environmental Potential Is Low Risk
The relevant criteria chosen for this organism are:  
Justification: North American pines are subject to attack by a number of indigenous bark beetles of the genus Ips. Many behave in a manner similar to Orthotomicus erosus. Introduction of O. erosus into North American pine ecosystems could lead to the displacement of native bark beetles provided that O. erosus can compete successfully.

Numerous fungi are associated with the Mediterranean pine engraver (Wingfield and Marasas 1980), some of which already occur in the United States, and others which may have not been identified. The introduction of the latter fungi could have disruptive effects in pine ecosystems, either as mortality agents or as organisms that compete with and displace native organisms.

Orthotomicus erosus breeds in a large number of pines throughout its natural range.

Indigenous European pine hosts include Canary Island pine, Pinus canariensis; Calabrian pine, Pinus brutia; Austrian pine, Pinus nigra and Pinus nigra ssp. pallasiana; maritime pine, Pinus pinaster; Italian stone pine, Pinus pinea; Scotch pine, Pinus sylvestris and a form of mugo pine, Pinus mugo subsp. uncinata.

Near Eastern hosts include two varieties of Calabrian pine, Pinus brutia var. eldarica and Pinus brutia, var. pityusa. Known Asian pine hosts are Masson pine, Pinus massoniana; Armand pine, Pinus armandii; Pinus kesiya, Yunnan pine, Pinus yunnanensis and Chinese pine, Pinus tabulaeformis.

Several North and Central American pines that have been planted in areas where this insect is native or has become established, including Coulter pine, Pinus coulteri; Caribbean pine, Pinus caribaea; shortleaf pine, Pinus echinata; Monterey pine, Pinus radiata; Mexican weeping pine, Pinus patula; and Eastern white pine, Pinus strobus.

Occasionally, maturing beetles feed in Douglas-fir, Pseudotsuga menziesii, Spruce, Picea spp.; Fir, Abies spp.; and Cedar, Cedrus spp. However Orthotomicus erosus does not breed in hosts other than pines.

     Mediterranean region including Algeria, Egypt, Libyia, Madiera Islands, Morocco and Tunisia. Introduced into Swaziland and South Africa (Wood and Bright 1992).
     This insect is widely distributed in Asia including China (Fuijan, Henan, Hunan, Jiangsu, Jiangxi, Shanxi, Sichuan and Yunnan Provinces, Iran, Cyprus, Israel, Jordan, Syria, and Turkey (Wood and Bright 1992). It has been introduced into Tajikistan.
Australasia & South Pacific:
     Introduced into Fiji (Wood and Bright 1992).
      Mediterranean region including France, Portugal, Spain, France, Switzerland, Italy, Bulgaria, Romania and Greece. There is some uncertainty about the distribution within central and northern Europe, with conflicting reports about occurrence of Orthotomicus erosus in Latvia, Germany, Austria, Poland, and the Nordic countries. Introduced into England.
South America:
      Orthotomicus erosus was introduced into Chile ca 1986.
The genus Orthomicus is a small genus of bark beetles found in Asia, Europe and North America and is closely related to the genus Ips. Twelve species are known worldwide. One species, O. caelatus, is indigenous to North America (Wood 1982). Wood and Bright (1992) placed O. erosus in the genus Ips. However, ten years later Bright and Skidmore (2002) reassigned it to Orthotomicus.

Orthotomicus erosus is polygamous. Males bore through the bark to the phloem-cambium layer where they construct a nuptial chamber. The males are joined by one to three females, each of which mates with the male and then constructs an individual egg gallery from the nuptial chamber, parallel to the grain of the wood. Typically, a female lays between 26 and 75 eggs in niches along the sides of the galleries (Mendel and Halperin 1982). Females will make "ventilation holes" in their egg galleries, and will sometimes abandon the gallery and finish their egg laying in another tree. The larvae mine at right angles to the parent gallery and pass through three instars during their development.

Adults must feed before reaching sexual maturation. This occurs beneath the bark of the brood host, providing the bark is still moist, or in another suitable host tree, sometimes of a different species. On occasion, the maturation feeding will take place during normal egg gallery construction and oviposition (Mendel and Halperin 1982).

The Mediterranean pine engraver completes two to seven generations per year, depending on temperature. Two generations per year are common in Turkey, France, and Morocco. In Tunisia, Chararas and M'Sadda (1973) found that O. erosus completed three and sometimes four generations in a year, with development time being a function of the nutritive quality of the wood as well as temperature. In Israel, where the beetle can complete three to five generations in a year, the time required for development of a brood varies from 25 days in the summer to 76 days in the winter (Mendel 1983). Based on these development times, Mendel (1983) concluded that coastal Israel could have as many as seven generations per year. Tribe (1990) estimated four generations per year in South Africa, with an average development time of 35 days for one generation.

The winter is spent in the adult stage. Between mid-October and December, adults aggregate beneath the bark of the host in which they developed, or in a new one. They enter the new host through a single hole and then concentrate as many as several hundred individuals in the phloem/cambium region (Mendel 1983). Beetle flight can occur through a broad temperature range of 14 to 38 degrees C (Chararas and M'Sadda 1973). In Israel, the threshold for flight is even lower during winter (12 degrees C) (Mendel 1983).

Orthotomicus erosus generally breeds in the rough-barked sections of the main trunk and in branches larger than 5 cm in diameter. Smooth-barked areas of host trees are used primarily for maturation feeding. The lower trunk of relatively old pines is not suitable because the bark is too thick. In Israel, trees younger than 5 years old are usually not attacked (Mendel and Halperin 1982). O. erosus commonly occurs in association with other bark beetles. Common associates on pines in Israel included Pityogenes calcaratus Eichhoff, Tomicus destruens (Wollaston), and Carphoborus minimus Fabricius (Mendel and Halperin 1982). In South Africa, Tribe (1990) found Hylastes angustatus (Herbst), Hylurgus ligniperda (Fabricius) (Coleoptera: Scolytidae) and Pissodes nemorensis Germar (Coleoptera: Curculioidae) associated with O. erosus. Ciesla (2004) reported the occurrence of the bark beetle Tomicus minor in the upper boles of trees infested by O. erosus in Cyprus.

Orthotomicus erosus is associated with a number of wood staining fungi, which also play a role in death of the host tree and cause degrade in lumber. Wingfield and Marasas (1980) described the association of O. erosus with Ophiostoma (= Ceratocystis) ips (Rumbold) Nannf., a pathogenic fungus occurring in Pinus pinaster and P. radiata in South Africa. They also discuss the association of this bark beetle with Verticicadiella alacris Wingfield & Marasas [= Leptographium serpens (Goid.) Siemaszko; = Ophiostoma serpens (Goid.) von Arx] in pines which together with other beetles and fungi form a pest complex that produces losses in pine plantations.

Economic Impact:    Orthotomicus erosus is usually a secondary bark beetle, which infests recently fallen trees, broken branches, slash, and standing trees that have been wounded or are under some form of stress (Mendel and Halperin 1982, Chararas and M'Sadda 1973). In Morocco, Questienne (1979) noted that bark beetles affected pine plantations more heavily than natural stands due to less-than-optimum climatic and edaphic conditions in the plantations. Baylis and others (1986) reported attacks of O. erosus on fire-damaged pines of various species, including Pinus radiata, P. elliottii and P. pinaster, in South Africa. Moisture deficiency is one of the key factors leading to attack by the Mediterranean engraver beetle. Bevan (1984) noted that O. erosus was normally secondary in plantations of Pinus patula and P. elliottii in Swaziland but would attack live trees under extreme drought stress. Serrao-Nogueira (1976) referred to trees weakened in urban settings by lack of water and then infested by O. erosus. In Italy, Capretti and others (1987) described O. erosus damage in 12 to 20 year-old Pinus halepensis plantations following a hot dry summer and cold winter.

Sometimes other insects or diseases are the stressing agents that lead to attacks by Orthotomicus erosus. In France, Carle (1971) noted that O. erosus was one of the beetles involved in the decline of Pinus pinaster following weakening of the host by the scale insect, Matsucoccus feytaudi Duc. . Zwolinski and others (1995), working in the Republic of South Africa, described the occurrence of O. erosus on Pinus radiata infected with Sphaeropsis sapinea (Fr.) Dyko & Sutton (= Diplodia pinea (Desm.) Kickx.). O. erosus was one of two beetles attacking these trees, and was confined to the zone of discoloration produced by the fungus.

Throughout its natural range, there have been reports of population buildups of Orthotomicus erosus in its typical host material, followed by attacks on healthy trees. In Israel, Halperin and others (1982) linked the increase of bark beetle outbreaks in Pinus halepensis to maturation of plantations and increased thinning. Also in Israel, Mendel and Halperin (1982) reported that the agents predisposing stands to attack were thinnings followed by winters of low rainfall, or fires in neighboring pine stands. Ferreira and Ferreira (1986) pointed out that O. erosus has periodically reached epidemic levels and has caused the death of many P. pinaster in Portugal.

Orthotomicus erosus has a broad host range. Moreover, its successful introduction and establishment into five countries shows adaptability to new hosts within the pine genus. Chararas (1973) reported that in Turkey, O. erosus was reared successfully on a variety of hosts, including some North American pines. In that study, O. erosus was little affected by differences in host terpenes, provided that they did not differ drastically from the original, or did not contain repellents such as heptane (found in Pinus jeffreyii).

Although obviously adaptable, the ability of to adapt to varying climatic conditions, hosts or compete with other insects may be questionable. In Chile, O. erosus was introduced in 1986, but was either not successful in competing with Hylurgus ligniperda, unable to adapt to the host, Pinus radiata, or local climatic conditions. It is now difficult to find O. erosus in Chile. However, Karnavar (1984) reported that O. erosus first appeared in Swaziland in the early 1980s and soon became a major pest.

Environmental Impact:   In its native habitat, Orthotomicus erosus is usually a secondary insect and, as such, is part of a complex of insects, fungi and other organisms that aid in the decomposition of dead trees. It is, however, capable of attacking and killing stressed trees.

North American pine forests serve as the habitat for a number of species of pine infesting bark beetles including one species of Orthotomicus (O. caelatus). Successful establishment of O. erosus is, in part, dependent on its ability to successfully compete and displace these insects. The competitive ability of O. erosus is questionable because of its relatively poor performance in Chile. Moreover, field observations in Chile and Cyprus, the latter being within this insect’s natural range, indicate that gallery patterns in Pinus radiata in Chile and in Pinus brutia in Cyprus were quite different. In Chile, this insect deposited clusters of eggs in short galleries and the larvae fed communally whereas in Cyprus, this insect produces galleries similar to those of bark beetles of the genus Ips. Eggs are deposited in individual niches and the larvae feed individually (Ciesla and Parra Sanhueza 1988, unpublished observations by W.M. Ciesla in Turkish Cyprus, 2000-2003).

Control:    Pest management methods for Orthotomicus erosus are fairly standard and primarily involve clean forest practices whereby slash, windthrow and other potential habitat is reduced to prevent population buildups. In South Africa, where O. erosus has been introduced, a classic biological control program, involving rearing and releases of the parasitoid Dendrosoter caenopachoides, was conducted. The program resulted in establishment of this parasitoid (Tribe and Kfir 2001).

Symptoms:    The most conspicuous indication of attack by Orthotomicus erosus is that the foliage of infested trees fades from green to yellow to reddish brown.

Breeding attacks are characterized by the presence of reddish-brown boring dust on the bark surface of trees, freshly cut logs, or windthrow. If relatively vigorous trees are attacked, pitch tubes may be found in the bark crevasses. The gallery pattern in the cambial region of infested trees consists of a nuptial chamber and one to five longitudinal egg galleries but could vary depending on host and location. Breeding attacks are accompanied by blue stain in the woody tissue.

Round exit holes are visible on the bark surface of trees where this insect has completed its life cycle and adults have emerged.

Morphology:    Orthotomicus erosus averages 3-3.8 mm length and is reddish brown in color. The adults are typical bark beetles of the subfamily Ipinae, family Scolytidae. The head is covered by a thoracic shield and is not visible when viewed dorsally and the declivity is concave, with each side armed by four spines, the second from the top being more conspicuous (Grüne 1979). The spines on the declivity of O. erosus are less conspicuous than on most North American species of Ips.

Eggs are pearly white in color. The larvae are white, legless, ‘C’ shaped grubs with an amber colored head capsule. Mature larvae are about 5 mm long. The pupae are white, mummy-like, and have some adult features, including wings that are folded behind the abdomen.

Testing Methods for Identification:    Species identification of bark beetles (Family Scolytidae) must be done from the adult stage. Identification of bark beetles, suspected of being exotic species, should be examined by a qualified insect taxonomist with expertise in the family Scolytidae.

Adult beetles are capable of flying considerable distances in search of suitable host materials. They are also subject to dispersal by winds.

All life stages of this insect is also easily transported by human assisted means, especially in pine crating material, pallets or dunnage containing bark strips. The host association and transportability of Orthotomicus erosus is strongly demonstrated by the observations of Schroeder (1990), who reported that six shipments of Pinus pinaster logs imported into Sweden from France all contained live larvae and adults of this engraver beneath the bark. Siitonen (1990) reported that O. erosus was found in Russian logs of P. sylvestris and other conifer genera, including Larix and Picea sent to Finland, a distance of over 5000 km. Also the large number of interceptions at U.S. ports of entry demonstrates its ability to be transported via wood in transit.

Baylis, N.T.; DeRonde, C.; James, D.B. 1986. Observations of damage of a secondary nature following a wild fire at the Otterford State Forest.[Abstract]. South African Forestry Journal 137: 36-37.
Bevan, D. 1984. Orthotomicus erosus (Wollaston) in Usutu pine plantations, Swaziland. [Abstract]. Forest Research Report, Usutu Pulp Company Limited. No. 64. 34 pp.
Bright, D.E., Skidmore, R.E. 2002. A catalogue of Scolytidae and Platypodidae (Coleoptera), Supplement 2 (1995-1999). Ottawa: NRC Research Press, 253 pp.
Capretti, P.; Panconesi, A.; Parrini, C. 1987. Osservazioni sul deperimento del pino d'Aleppo e del pino marittimo in rimboschimento dell'Alta Maremma. [Abstract]. Monti e Boschi 38(1): 42-46 (In Italian).
Carle, P. 1971. Les phenomenes presidant aux successions d'insectes dans le deperissement du pin maritime du Var. [Abstract]. Annales de Zoologie, Ecologie Animale 3: 177-192 (In French).
Chararas, C. 1973. Adaptability of Orthotomicus erosus to conifers other than its usual host species. [Abstract]. Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences, France, D. 276(4): 555-558.
Chararas, C.; M'Sadda, K. 1973. Etude de la biologie, du comportement et de l'action des radiations ionisantes Cobalt60 chez Orthotomicus erosus Woll., Coleoptere Scolytidae parasite specifique des coniferes [Abstract]. Archives de l'Institut Pasteur de Tunis 50(3): 243-265 (In French).
Cibrián Tovar, D.; Méndez Monteil , J.T.; Campos Bolanòs, R.; Yates, H.O. III, Flores Lara, J. 1995. Forest insects of Mexico. North American Forestry Commission, FAO, Publication 6, 453 pp. (In English and Spanish).
Ciesla, W.M. 2004. Forests and forest protection in Cyprus. Forestry Chronicle 80(1):1-7.
Ciesla, W.M.; Parra Sanhueza, P. 1988. Orthotomicus erosus Corporación Nacional Forestal, Protección Fitosanitaria Forestal (Chile). Folleto de Divulgación, Ano 8 N 16. 8 pp. (In Spanish).
Drooz, A.T. 1985 . Insects of eastern forests. USDA Forest Service, Miscellaneous Publication 1426, 608 pp.
Ferreira, M.C.; Ferreira, G.W.S. 1986. Pragas do pinheiro bravo em Portugal - escolitideos. [Abstract]. Boletim Agricola No. 36. 4 pp. (In Portuguese).
Furniss, R. L.; Carolin, V.M. 1977. Western forest insects. USDA Forest Service, Miscellaneous Publication 1339, 654 pp.
Grüne, S. 1979. Handbuch zur bestimmung der europäischen Borkenkäfer (Brief illustrated key to European bark beetles). Hannover, Germany: Verlag M.& H. Schaper, 182 pp. (In English and German).
Haack, R.A. 2001. Intercepted Scolytidae at U.S. ports of entry: 1985-2000. Integrated Pest Management Reviews 6(3): 253-282.
Halperin, J.; Mendel, Z.; Golan, Y. 1982. On the damage caused by bark beetles to pine plantations. Preliminary report. [Abstract]. La-Yaraan 32: 1-4, 31-38.
Karnavar, G.K. 1984. Preliminary studies on the use of 2-methyl-3-buten-2-ol as an attractant for the pine bark beetle, Orthotomicus erosus. [Abstract]. Journal of the Royal Swaziland Society of Science and Technology 5(2): 2-4.
Mendel, Z. 1983. Seasonal history of Orthotomicus erosus (Coleoptera: Scolytidae) in Israel. Phytoparasitica 11(1): 13-24.
Mendel, Z.; Halperin, J. 1982. The biology and behavior of Orthotomicus erosus in Israel. Phytoparasitica 10(2): 169-181.
Questienne, P. 1979. Notes sur quelques insectes nuisibles aux pins au Maroc. [Abstract]. Annales de Gembloux 85(2): 113-130 (In French).
Schroeder, L.M. 1990. Occurrence of insects in coniferous roundwood imported to Sweden from France and Chile. EPPO (European and Mediterranean Plant Protection Organization) Bulletin. 20: 591-596.
Serrao-Nogueira, C.D. 1976. O problem fitossanitario dos pinhais do Estaril. [Abstract]. Anais do Instituto Superior de Agronomia 36: 203-240 (In Portuguese).
Siitonen, J. 1990. Potential forest pests conveyed to Finland on timber from the Soviet Union. [Abstract]. Silva Fennica 24(3): 315-321.
Tribe, G.D., Kfir, R. 2001. The establishment of Dendrosoter caenopachoides (Hymenoptera: Braconidae) introduced into South Africa for the biological control of Orthotomicus erosus (Coleoptera: Scolytidae), with additional notes on D. sp. nr. labdacus. African Entomology 9: 195-198.
Tribe, G.W. 1990. Phenology of Pinus radiata log colonization and reproduction by the European bark beetle Orthotomicus erosus (Wollaston) (Coleoptera: Scolytidae) in the south-western Cape Province [Abstract]. Journal of the Entomological Society of Southern Africa 53(2): 117-126.
Wingfield, M.J.; Marasas, W.F.O. 1980. Ceratocystis ips associated with Orthotomicus erosus (Coleoptera: Scolytidae) on Pinus spp. in the Cape Province of South Africa. [Abstract]. Phytophylactica 12(2): 65-69.
Wood, S.L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolytidae), a taxonomic monograph. Great Basin Naturalist Memoirs 6, 1359 pp.
Wood, S.L.; Bright, D.E. 1992. A catalog of Scolytidae and Platypodidae (Coleoptera), Part 2: Taxonomic index. Great Basin Naturalist Memoirs 13, 1553 pp.
Zwolinski, J.B.; Swart, W.J.; Wingfield, M.J. 1995. Association of Sphaeropsis sapinea with insect infestation following hail damage of Pinus radiata. [Abstract]. Forest Ecology and Management 72: 2-3.
Andris Eglitis
Name and Address of the First Author:
Andris Eglitis
Central Oregon Insect and Disease Area Office
USDA Forest Service
1645 Highway 20 East
Bend, OR
USA 97701
CREATION DATE:        02/08/00
MODIFICATION DATE:        09/12/00

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Photo by William M. Ciesla,
Forest Health Management International


Photo by William M. Ciesla,
Forest Health Management International


Pinus brutia killed by Mediterranean pine beetle, Turkish Cyprus
Photo by William M. Ciesla,
Forest Health Management International