Hylurgus ligniperda

Name:   Hylurgus ligniperda
Pest Authorities:  (Fabricius)
Taxonomic Position:  Insecta: Coleoptera: Scolytidae
Sub-specific Taxon:  
Pest Type:   Insect
Common Name(s):
   Golden-haired bark beetle (English)
   Red-haired pine bark beetle (English)
   Rothaariger Kiefernbastkäfer (German)
   Hylesinus ligniperda Fabricius
   Hylurgus elongates Herbst
   Hylurgus flavipes Panzer
Numerical Score:  9
Relative Risk Rating:  Very High Risk
Uncertainty:   Uncertain
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: Hylurgus ligniperda is established in North America. An overwintering colony of adults was discovered in November 2000 in an eastern white pine, Pinus strobus, Christmas tree plantation near Rochester, NY (USDA Forest Service 2002). Moreover, according to data from the National Agricultural Pest Information System (NAPIS), adults have also been captured in three counties in NY (Monroe, Ontario and Wayne) since 1994. Between 1985 and 2000, this insect was intercepted 217 times at US ports of entry (Haack 2001). This insect would find suitable climate and hosts (pines) at many North American ports of entry and has demonstrated its ability to adapt to a number of North American pine species.

Spread Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Organism is capable of dispersing more than several km per year through its own movement or by abiotic factors (such as wind, water or vectors).
  • 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.
  • Eradication techniques are unknown, infeasible, or expected to be ineffective.
  • Organism has broad host range.
Justification: Adults are strong fliers, capable of flying several km to find suitable hosts. They are also subject to wind dispersal. The immature stages are easily moved via unprocessed logs or on lumber, packing materials, pallets and dunnage containing bark strips. This insect has a high reproductive potential and because of its similarity to many species of indigenous bark beetles, it would be difficult to detect and eradicate. Another factor that makes the potential for spread of infestations high is the more or less continuous distribution of its hosts, species of Pinus, across North America.

The ability of this insect to spread rapidly is exemplified by its behavior in places where it has been introduced. In Australia, infestations spread 25 km from an area of fire kill within 18 months (Neumann 1987). In Chile, by the time this insect was discovered, it was distributed throughout over 1 million ha of Pinus radiata plantations in the country (Ciesla 1998).

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: Pines are important commercial trees species in much of North America. The impacts of this pest are expected to be an increase in the prevalence of staining fungi in pine logs and increased seedling mortality due to adult maturation feeding. Stain reduces the value of lumber and can increase production costs of some wood products such as high quality paper.

Hylurgus ligniperda is known to be a vector of several species of root disease causing fungi of the genus Leptographium. Currently, the fungus Leptographium procerum, which causes procera root disease of eastern white pine, Pinus strobus, is uncommon in the northwestern United States (Sinclair et al. 1987), although it has been detected there on occasion (D. Goheen 1999, personal communication). The introduction of H. ligniperda to the West could broaden the distribution of this occasionally pathogenic fungus in pine forests or Christmas tree plantations not previously exposed to procera root disease. Black stain root disease, caused by the fungus Leptographium wagneri, is a major disease of several conifers in the West and is known to be vectored by several indigenous bark beetles and weevils (Cobb 1988). Should H. ligniperda become established in the West, it has the potential to become a vector of this fungus.

Environmental Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Organism is expected to cause significant direct environmental effects, such as extensive ecological disruption or large scale reduction of biodiversity.
  • Introduction of the organism would likely result in control/eradication programs that may have potential adverse environmental affects.
Justification: Introduction of Hylurgus ligniperda, an efficient vector of fungi of the genus Leptographium that cause root disease, could result in increased mortality of pines. This could be the direct result of root disease occurrence or increased bark beetle activity in trees weakened by root disease (Cobb 1988).

Another ecological effect of establishment of this insect could be the displacement of native bark beetles that occupy similar ecological niches as does Hylurgus ligniperda.

Hylurgus ligniperda attacks a number of pines within its natural range. These include Canary Island pine, Pinus canariensis, Aleppo pine, Pinus halepensis, Calabrian pine, Pinus brutia, Austrian pine, Pinus nigra, Cyprus pine, Pinus nigra ssp. pallasiana, Maritime pine, Pinus pinaster, Italian stone pine, Pinus pinea and Scotch pine, Pinus sylvestris.

North American pines that have been reported as hosts include Slash pine, Pinus elliottii, Monterey pine, Pinus radiata, eastern white pine, Pinus strobus, Montezuma pine, Pinus montezumae, and Mexican weeping pine, Pinus patula (Browne 1968).

      Hylurgus ligniperda is indigenous to the Azores Islands (Portugal), Canary Islands (Spain), Madiera Islands (Portugal) and Morocco (Wood and Bright 1992). It has been introduced into South Africa, St. Helena, an island in the South Atlantic Ocean and Swaziland (Browne 1968)
      This insect is reported from China (Manchuria), Japan and Turkey (Wood and Bright 1992). According to Browne (1968), it was introduced into Japan and Sri Lanka.
Australasia & South Pacific:
      Introduced into Australia (Neumann 1979) and New Zealand (Bain 1977).
      Occurs throughout Europe including Great Britain and the Mediterranean Basin (Schwenke 1974), the Caucasus Mountains, and western Siberia. Specific country records include Austria, Belgium, Czech Republic, Denmark, England, Estonia, Finland, France (Corsica), Germany, Greece, Hungary, Italy, Latvia, Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland, European Russia, and the former Yugoslav Republics (Bright and Skidmore 2002, Wood and Bright 1992).
North America:
     An overwintering colony of Hylurgus ligniperda was discovered near Rochester, NY, U.S. in 2000 (USDA Forest Service 2000).
South America:
      Introduced into Brazil (Schönherr and Pedrosa-Macedo 1981), Chile (Ciesla 1988) and Uruguay (Wood and Bright 1992).
The genus is a small genus of bark beetles native to Europe. There are no indigenous species in North America.

Hylurgus ligniperda breeds in fresh stumps, slash from recently felled trees and buried logs or portions of logs in contact with the soil (Ciesla 1988, Tribe 1992). Occasionally, the base and roots of weakened or wounded standing trees are attacked (Browne 1968, Fabre and Carle 1975). In Chile, H. ligniperda has been found in standing trees during drought periods (L. Cerda 1992, personal communication). During maturation feeding, adults strip the bark from pine seedlings and kill them. In Chile, natural pine regeneration or seedlings that have malformed roots caused by poor planting or bark injury caused by other insects or small mammals are more likely to be selected for adult maturation feeding than are vigorous seedlings (Ciesla 1988).

This species is monogamous (Browne 1968). Females initiate attacks by boring through the bark and constructing a small chamber under the bark. Males join the females and mating takes place in these chambers. Females then construct a long winding oviposition gallery and lay eggs individually in niches cut in the sides of the gallery. One female can lay up to 500 eggs. Larvae feed beneath the bark and pupate once they mature. Adults emerge and fly to new hosts at various times of the year. The insects generally complete more than one generation per year. In France, there are two generations per year (Fabre and Carle 1975) with first-generation adults laying eggs in the winter and spring, and the second generation laying eggs in the fall. In Chile, Hylastes ligniperda completes three generations per year (Cogollor 1991) and adults can be found virtually year-round. In South Africa, adults are also present throughout the year but are most active during periods of cool temperatures and high humidity, peaking in the fall (April - May) with minor peaks in the spring (September) and summer (January) (Tribe 1991a, 1991b).

Two species of Leptographium: L. truncatum (Wingfield and Marasas) Wingfield and L. procerum (Kendrick) M.J. Wingfield have been isolated from New Zealand populations of Hylurgus ligniperda (Wingfield et al. 1988, MacKenzie 1992). Leptographium truncatum, a possible synonym of L. lundbergii Lagerberg & Melin (Wingfield and Gibbs 1991), which occurs in Canada, is a reported pathogen of Pinus radiata and P. strobus in New Zealand (Wingfield and Marasas 1983). Inoculation tests indicate that L. truncatum is not highly virulent and may be opportunistic (Wingfield et al. 1988).

Procera root disease, caused by Leptographium procerum (= Verticicladiella procera Kendrick) is an important disease of eastern white pines, Pinus strobus in the eastern United States (Sinclair et al. 1987), and causes serious damage to Christmas tree plantations in Virginia (Lackner and Alexander 1982, 1984). L. procerum also affects numerous other pines. The association of these fungi with Hylurgus ligniperda in New Zealand is high, with the fungus having been isolated from more than 70% of the beetles examined (MacKenzie 1992). In South Africa, H. ligniperda is commonly associated with Ophiostoma (= Ceratocystis) ips (Rumbold) Nannf. and Leptographium serpens (Goid.) Siemaszko (= Ophiostoma serpens (Goid.) von Arx), and an unidentified Leptographium sp. (Wingfield et al. 1985). Symptoms of a black staining root disease have been noted on some Hylurgus ligniperda infested Monterey pines in Chile (Ciesla 1988, Gara et al. 1988), but the fungus species has not been identified.

Adults can disperse over distances of several kilometers (Fabre and Carle 1975) and an infestation can spread as long as host material is available. In Australia, H. ligniperda spread up to 25 km from a fire-killed area within 18 months (Neumann 1987). When this insect was introduced into Chile in the mid-1980s, it spread rapidly throughout the entire distribution of Monterey pine in the country Ciesla 1988).

In Chile, Hylurgus ligniperda has demonstrated a competitive advantage over at least other introduced bark beetles: Hylastes ater and Orthotomicus erosus. Although the initial distribution and habitats were similar when all three were introduced into Chile in the 1980s, H. ligniperda eventually supplanted the other two species. Now only H. ligniperda is abundant in Pinus radiata plantations (Cogollor 1991).

Economic Impact:    This insect has the potential to cause economic damage to pines in four ways. It could serve as a more efficient vector of root disease fungi, especially those of the genus Leptographium, resulting in increased mortality of medium to large trees both in plantations and natural forests. Adult maturation feeding could cause accelerated mortality of pine seedlings. Infestations in weakened or stressed trees would result in accelerated tree mortality. Increased occurrence of wood staining fungi associated with Hylurgus ligniperda in harvested logs that are left in the forest for extended periods or not debarked at the mill could result in loss of quality.

Environmental Impact:   Environmental impacts of this insect could include accelerated seedling and tree mortality due to adult maturation feeding and/or the spread of root disease causing fungi. This could result in a loss of the competitive ability of pines in mixed forests. Moreover, Hylurgus ligniperda could displace less aggressive species of bark beetles.

Control:    Wood materials can be treated with fumigant, insecticide, or anti-sapstain spray at the port of entry.

Protection of seedlings requires both roots and stems be treated with insecticide prior to planting (Tribe 1992). Subsequent sprays of the stem and bole should include some run-off to penetrate the soil around the root collar.

Populations may be reduced through silvicultural tactics such as delaying planting until stumps and slash are no longer suitable breeding sites, improving slash disposal and planting of vigorous seedlings in a manner that prevents “j”-rooting. (Ciesla 1988).

Temnochila virescens F. (Coleoptera: Trogositidae), a predator of the five-spined engraver beetle, Ips grandicollis Eichh. and other bark beetles, will feed on Hylurgus ligniperda (Lawson and Morgan 1993).

Symptoms:    Symptoms of breeding attacks include reddish colored boring dust and exit holes on the bark surface of fresh cut stumps, logging slash, logs and weakened trees, presence of long, winding egg galleries and brood under the bark and presence of staining fungi.

Adult maturation feeding is characterized by occurrence of pine seedling mortality. Examination of dead seedlings will reveal bark stripped by feeding adults.

Morphology:    Eggs are pearly white in color. The larvae are white, ‘C’-shaped grubs with an amber colored head capsule. Mature larvae are from 5 to 8 mm long. The pupae are white, mummy-like, and have some adult features, including wings that are folded behind the abdomen.

Hylurgus ligniperda is a member of the subfamily Hylesininae. Adults are characterized by heads being visible when viewed dorsally and smooth, rounded wing coverings (elytra). They are 2 mm wide, 6 mm long, dark brown to black in color and covered with reddish hairs, which give this insect its common name. The hairs are most conspicuous on the posterior slopes of the wing covers (USDA Forest Service 2000).

Testing Methods for Identification:    Examination of adults by a scolytid specialist is required for positive identification.

Adults can disperse over distances of several km (Fabre and Carle 1975) and an infestation can spread as long as suitable host material is available.

Hylurgus ligniperda is also readily transported on cut logs or wooden packing material, pallets and dunnage containing bark strips. Between 1985 and 2000, this insect was intercepted 217 times, mostly from crating containing tiles and marble from the Mediterranean Region (Haack 2001).

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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:        01/31/01
MODIFICATION DATE:        01/31/01