Tetropium staudingeri

Name:   Tetropium staudingeri
Pest Authorities:  Pic
Taxonomic Position:  Insecta: Coleoptera: Cerambycidae
Sub-specific Taxon:  
Pest Type:   Insect
Common Name(s):
   Seven-river spruce borer (English)
   Staudinger's spruce borer (Engish)
   Tetropium staudingeri Plavilstshikov
   Tetropium tjanshanicum Semenov
Numerical Score:  9
Relative Risk Rating:  Very High Risk
Uncertainty:   Very Uncertain
Uncertainty in this assessment results from: Tetropium staudingeri has been found on a single host, Picea schrenkiana. Because this is the only species of spruce within this insect's geographic range, it is not clear whether T. staudingeri can adapt to other species of spruce.

Establishment Potential Is High Risk
The relevant criteria chosen for this organism are:  
  • Suitable climatic conditions and suitable host material coincide with ports of entry or major destinations.
  • 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: Suitable climatic conditions for Tetropium staudingeri coincide with many North American ports of entry, especially in the northern U.S. and Canada. The only known host of this insect is the central Asian spruce, Picea schrenkiana. Provided that this insect can adapt to North American species of Picea, it would find suitable host material in many northern ports of entry on both the Atlantic and Pacific coasts. Again, provided that this insect is able to adapt to North American spruces, it is expected to have a high likelihood of reproducing after entry.

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 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.
Justification: Tetropium staudingeri is a strong flier and adults can travel several km. If it can adapt to North American species of spruce, especially white spruce, Picea glauca and black spruce, P. mariana, which are transcontinental components of the North American boreal forest, it would find an abundant and contiguous supply of host material. This insect also has a high reproductive potential. Exotic species of Tetropium would be difficult to detect because they are similar in appearance to indigenous species. This, coupled with logistical problems in remote forest areas would make eradication extremely difficult.

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.
  • No effective control measure exists.
Justification: Tetropium staudingeri is a common insect within its natural range and one of the most important pests of spruce. It may attack slightly stressed and healthy trees of different ages and re-attacks the same trees over several consecutive years, eventually causing their death. This insect prefers to attack mature trees and, even in cases when it does not kill them, infestations result in significant loss of tree vigor and wood quality.

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: Wood boring insects, like Tetropium staudingeri, are instrumental in the decomposition of dead and dying trees, logging residues and stumps. Because it is a tree-killer, T. staudingeri can alter tree species composition in favor of non-host species where spruce is an important component of forests. In its present range, this insect primarily damages mountain forests, which are important for soil protection against erosion and watershed protection and may alter the mountain environment.

Indigenous activity of indigenous insects and the hazard of wildfires of increased frequency and severity could occur in North American forests as a result of increased tree mortality caused by establishment of this insect.

Control and eradication programs could lead to undesirable environmental impacts associated with chemical or mechanical treatments.

Tetropium staudingeri attacks the central Asian spruce, Picea schrenkiana (=P. tianschanica = P. prostrata = P. robertii), (Maslov 1988). Many authors record Picea schrenkiana as the only host plant for this insect (Plavilshchikov 1940, Pavlovskii and Shtakelberg 1955, Makhnovskii 1966), which is the only species of spruce within the natural range of this insect.

     This insect has been recorded from northwestern China (Xinjiang Province) and central Asia, including Kazakhstan, Kyrgyzstan and Uzbekistan (Pavlovskii and Shtakelberg 1955, Makhnovskii 1960, 1966, Maslov 1988).
The genus Tetropium is a large genus of conifer infesting longhorned woodborers. Members of this genus are found in conifer forests of Asia, Europe and North America. Several species are reported capable of killing living trees and one species, T. fuscum, has recently become established near Halifax, Nova Scotia, Canada. Species indigenous to North America include: T. cinnamopterum and T. velutinum, which occur both in eastern and western North America, T. schwarzianus from eastern Canada and T. abietis and T. parvulum in western North America (Knull 1946, Furniss and Carolin 1977).

Tetropium staudingeri requires one year to complete a generation in the southern parts of its range and at low altitudes. Two years are required in the northern parts of its range and at high altitudes (Parfentiev 1951, Makhnovskii 1966, Vorontsov 1995).

Adult flight occurs during May and June in the southern parts of its area and at low altitudes, and during the first half of July in the northern parts of its area and at high altitudes. This insect attacks stressed, dying, recently cut trees and stumps. T. staudingeri usually lays eggs in cracks in the bark on the lower bole of mature trees. On cut trees, eggs are deposited on the underside of logs.

The larvae construct large irregular galleries in the sapwood and overwinter for one or two seasons depending on location and altitude. . For pupation, the larva bores to a depth of 1.5-2.5 cm into the wood and makes a vertical, 6-7 cm long gallery oriented downwards and curved at the end. The pupal cell is oriented horizontally. Prior to pupation, the larva makes the emergence hole and seals it with frass (Parfentiev 1951, Makhnovskii 1966).

Tetropium staudingeri often attacks trees in association with Dokhtouroffia baeckmanni (Coleoptera: Cerambycidae) and the bark beetles Ips hauseri and Pityogenes spessivtsevi (Coleoptera: Scolytidae). If the level of infestation is high (8 to 10 T. staudingeri larvae per square dm.), it supplants bark beetles, which normally occupy the upper parts of the trunk, in competition for available food. In stumps, this insect often occurs in association with the longhorn beetle, Asemum striatum.

Economic Impact:    This woodborer is one of the most important and common pests of spruce within its natural range. It may attack slightly stressed and healthy trees of different ages and continues to attack the same trees over several consecutive years, eventually causing their death. This species prefers to attack mature trees and, even in cases where it does not kill them, the infestation results in significant loss of vigor and wood marketability due to larval boring. This insect occurs primarily in mountain forests, which are important for protection of watersheds and subject to soil erosion. It is one of the most common and damaging pests of spruce forests stressed by insect defoliators, damaged by diseases or forest fires. Its outbreaks sometimes lead to the death of trees and forests, either by itself or in association with other insects (Parfentiev 1951, Makhnovskii 1966, Maslov 1988, Vorontsov 1995).

Environmental Impact:   Wood boring insects, including Tetropium staudingeri, are instrumental in decomposition of dead and dying trees, logging residues and stumps. T. staudingeri can kill trees and, therefore, change species composition of forests with a spruce component in favor of non-host species. This insect is primarily a pest of mountain forests and may alter the environment by, among other things, leading to erosion.

Control:    In parts of its natural range, Tetropium staudingeri causes enough damage to require direct control. Control measures make use of silvicultural tactics designed to improve overall forest health and vigor. These include cutting and elimination of all infested trees, use of trap trees subsequently treated with chemicals and treatments with chemical and biological insecticides (Maslov 1988, Vorontsov 1995).

Eradication of infestations would involve destruction of infested trees and quarantine measures to restrict movement of infested wood products.

Symptoms:    Evidence of infestation includes larval feeding galleries filled with granular frass, oval shaped exit holes and fading foliage of host trees. These symptoms are not specific to Tetropium staudingeri, however, and are typical of many bark beetles and wood boring insects.

Morphology:    The egg is elongated, rounded at the ends, and covered at the ends by small cells.

The larva is yellowish-white with a darker pronotum and head, and black mandibles. The head is chordate and has a longitudinal fissure in the middle. The ninth abdominal tergite has a pair of small thorns at the top.

The pupa has an elongated body. The abdominal tergite has multiple acute thorns from both sides of a longitudinal fissure. The top of the abdomen has a pair of urogomphal outgrowths, which finish in sclerotised thorns.

The adult of Tetropium staudingeri is slightly flattened, 11-17 mm long and has elongated elytra and long antennae with knotted tops of the second to the fifth segments. The head is widely punctuated and covered by long hairs, and has a wide and deep longitudinal fissure between the antennae and between the eyes. This fissure sometimes reaches the rounded back border of the head. The male antennae extend longer than the mid length of the elytra; the female antennae reach one third of the length of the elytra. The eleventh segment of the female antenna is shorter than the fourth segment. The pronotum has a variable shape and variable fissures and depressions; it is widely punctuated and covered by long hairs, bright in the middle part and mat at the borders. The male pronotum is usually longer than wide; the female pronotum usually has equal length and width, but sometimes much wider than long. The scutellum is elongated, covered by punctuation from both sides of a wide longitudinal fissure. The elytra have parallel borders and are covered by fine punctuations and small hairs. The thorax and abdomen are covered by fine punctuations and by yellow or yellowish-brown hairs. The fifth female abdominal segment is much elongated. The color of the beetle varies considerably. For the typical form, the entire beetle is black, but very often the body is black and the elytra, legs and antennae are brown or reddish-brown (Plavilshchikov 1940).

Testing Methods for Identification:    Examination of adults by a taxonomist with expertise in the family Cerambycidae is required for positive identification. The adults and larval galleries have sufficient characteristics to permit entomologists to make field identifications at least to genus.

Adults are strong fliers and could travel several km in search of suitable host trees.

All life stages could be moved via unprocessed logs, lumber, wooden crating, pallets and dunnage. The borings may be blocked by frass and difficult to detect. Other species of Tetropium have been intercepted at international ports of entry and T. fuscum has become established in the vicinity of Halifax, Nova Scotia, Canada (Anon. 2000). All interceptions and introductions of Tetropium spp. have been via wood products in international trade.

Anonymous 2000. Questions and answers about the brown spruce longhorn beetle - Tetropium fuscum (Fabr.). Ontario's Forests - Management for Today and Tomorrow. On line: http://www.mnr.gov.on.ca/MNR/forests/foresthealth/brown%20spruce/longhirn_beetle.htm
Furniss, R.L.; Carolin, V.M. 1977. Western forest insects USDA Forest Service, Miscellaneous Publication 1339, 654 pp.
Knull, J.N. 1946. The long-horned beetles of Ohio (Coleoptera: Cerambycidae) Ohio Biological Survey, Bulletin 39, 354 pp
Makhnovskii, I. K. 1960. Pests of spruce-fir forest of Chatkal' and Fergan Mountain ridges. Tashkent: Edition of Academy of Agricultural Sciences of Uzbekistan, 49 pp (in Russian).
Makhnovskii, I. K. 1966. Seven-river borer, Tetropium staudingeri Pic. In: Pests of Mountain Forests and Their Control. Moscow: Lesnaïya Promyshlennost, pp. 42-43 (in Russian).
Maslov, A. D. 1988. Guide on forest protection against pests and diseases. Moscow: Agropromizdat, 414 pp. (in Russian).
Parfentiev, V. Ya. 1951. Bark beetles and longhorn beetles of Picea schrenkiana. Entomologicheskoe Obozrenie 31: 428 - 434 (in Russian).
Pavlovskii, E. N.; Shtakelberg A. A. (Editors). 1955. Forest pests guide. Moscow-Leningrad: Edition of Academy of Sciences of the USSR, V 2, pp. 422-1097 (in Russian).
Plavilshchikov, N. N. 1940. Tetropium staudingeri Pic - Seven-river spruce borer. In: Fauna of the USSR; Coleopterous insects", V. XXII; Long horn beetles, Part 2, pp. 36-37 (in Russian).
Vorontsov, A. I. 1995. Forest Entomology. Manual for Universities, 5th edition. Moscow: Ecologia, 352 pp. (in Russian).
Andrei Dorian Orlinski
T.V. Bassova; D.G. McNamara 
Name and Address of the First Author:
Andrei Dorian Orlinski
1, rue Le Nôtre
France 75016
CREATION DATE:        05/09/02