Monochamus sutor
(small white-marmorated longicorn)

M. sutor is found throughout the conifer forests of Eurasia from the Atlantic Coast east to the Pacific (Cherepanov, 1990).

Official surveys have been carried out regularly in Denmark since 2000. None of the pre-surveillance records reported in Bílý and Mehl (1989) or Althoff and Danilevsky (1997), or later transient interceptions have led to the establishment of Monochamus species. It is therefore concluded that Monochamus species are not known to occur in Denmark (Danish Plant Directorate, 2010).

Adult Monochamus beetles are strong fliers. However, the normal flying distance for Monochamus adults in forests is fairly short. In the case of Monochamus alternatus, an important vector of pinewood nematode in China and Japan, most adults fly less than 200 m, although some individuals have been known to fly up to 3.3 km (Kobayashi et al., 1984; USDA APHIS, 1999).

All life stages of M. sutor can be transported over long distances via international trade in unprocessed logs. The larvae and pupae can survive in lumber cut from infested logs and can develop into adults. Lumber, wooden crating, pallets and dunnage used in international trade are therefore potential sources of introduction of M. sutor and other species of Monochamus. According to data available from APHIS, insects identified as Monochamus spp. were intercepted over 250 times at ports of entry in the USA between 1985 and 1998. A single adult M. sutor was intercepted from wooden crating arriving at the airport in Curitiba, Brazil, from Italy (ET Iede, EMBRAPA, Parana, Brazil, personal communication, 2001). In 1998, more than 100,000 m³ of larch was imported from Russia to Austria. This material contained several species of longhorned beetles including M. sutor (Krehan and Holzschuh, 1999).

M. sutor is a known vector of a Eurasian pinewood nematode, Bursaphelenchus mucronatus (Tomminen et al., 1989; Schroeder and Magnusson, 1992). Infection occurs during adult maturation feeding and oviposition when the nematode larvae emerge from the spiracles of beetles, drop onto the twigs and penetrate the woody tissue through the feeding wounds (Speight and Wainhouse, 1989). Damage caused by this nematode in the forests of Europe and Asia is minimal and similar to that caused by the pinewood nematode (Bursaphelenchus xylophilus) in North America. However, when B. xylophilus was introduced into Asia, it became a devastating pathogen (Kulinich and Orlinski, 1998). B. mucronatus must therefore be regarded as having the potential to become a devastating pathogen of North American conifers. Three other nematodes, Parasitorhabditis welchi, Bursaphelenchus sutoricus and Cryptaphelenchus sutoricus, are reported to be associated with M. sutor in the Republic of Georgia (Devdariani, 1974).

Within its native distribution, M. sutor generally confines its attacks to stressed or recently killed trees and freshly cut logs or windthrow. In Siberia, mass breeding occurs in forests damaged by wildfire or defoliated by the Siberian silkworm, Dendrolimus sibiricus, and in recently felled trees (Cherepanov, 1990).

M. sutor attacks species of fir (Abies), spruce (Picea), pine (Pinus) and larch (Larix) across its geographic range. In Europe, Abies alba, Picea abies and Pinus sylvestris are attacked (Hellrigl, 1971; Bakke and Kvamme, 1992; Schroeder et al., 1999). In China, reported hosts are Larix gmelinii, Pinus sylvestris var. mongolica and Betula platyphylla (Zhang et al.,1993; Li et al., 1988). In Siberia and the Russian Far East, M. sutor is reported from Abies holophylla, A. nephrolepis, A. sibirica, Larix gmelinii, L. sibirica, Picea koraiensis, P. jezoensis, P. obovata, Pinus sylvestris and P. sibirica (USDA Forest Service, 1991).

Life History and Habits

The genus Monochamus is comprised of 150 known species distributed across Asia, Africa, Europe and North America (USDA APHIS, 1999). Twenty-four species of Monochamus have been recorded from China and about 10 species are native to North America (Furniss and Carolin, 1977; Drooz, 1985; USDA APHIS, 1999). All species indigenous to the temperate regions attack various species of Pinaceae and confine their attacks to trees that are stressed or recently killed by bark beetles, lightning, disease or climatic and site-related factors. Some species can be damaging to windthrow or recently felled pulpwood or sawlogs. Several African species of Monochamus are pests of tropical broadleaf trees and some (e.g. M. scabiosus) have a tendency to attack healthy trees (Browne, 1968).

In Siberia, M. sutor has a 2-year life cycle. Adult flight occurs between June and mid-September. After the adults emerge from host trees, they feed on the bark and phloem of twigs in the crowns of conifers. The damaged shoots often break off, giving the trees a pruned appearance. Adults are attracted to weakened, dying or recently dead trees or logs to mate and lay eggs (Cherepanov, 1990).

Females deposit about 50 eggs, in groups of 1-6 eggs, in niches cut into the bark of host trees (USDA Forest Service, 1991). In northern China, trees are suitable for attack from the trunk base to within 3.3-4.6 m from the top for trees 13-23 m in height (Zhang et al., 1993). During the first year, the larvae feed under the bark. They later bore into the wood, constructing oval galleries, where they overwinter as second-instar larvae. During the second year, the larvae continue to feed and bore deeper into the wood. The larvae have five instars. Mature larvae form pupal cells near the bark surface, where they spend the second winter as pupae. Adult emergence occurs in the following spring (USDA Forest Service, 1991).

Little is known about the natural enemy complex of M. sutor. The larvae can be cannibalistic (Victorsson and Wikars, 1996). A large wasp, Rhyssa persuasoria, reportedly parasitizes the larvae (BBC, 2004).

Look for larval galleries, granular frass and various life stages of the insect in unprocessed logs, lumber, wooden crating, pallets and dunnage. The presence of round or slightly oval exit holes in logs or wood in use is an indication that adults of the genus Monochamus may have emerged from this material.

Adults tend to be similar in appearance to other palaearctic species of Monochamus. Examination of adults by a taxonomist with expertise in the family Cerambycidae is necessary for sound species identification, especially if specimens are found outside of its known geographic range.

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Cultural Control

Recommended cultural measures for the management of various species of Monochamus emphasize the prevention of attacks. These measures include avoiding storage of recently felled sawtimber and pulpwood in forested areas during the adult flight period, which is usually from May to September; prompt salvage and utilization of windthrow and/or trees killed by bark beetles, lightning or disease and storage of logs under a water spray at sawmill sites (Furniss and Carolin, 1977; Drooz, 1985).

Chemical Control

No chemical control methods are available for M. sutor.

Mechanical Control

Heat treatment at 60 or 70°C for 1 hour kills all stages of Monochamus urussovii. This could be accomplished in a kiln or with steam or hot-water treatment (USDA APHIS, 1991). This treatment should be effective for all species of Monochamus and could be applied to wood products destined for export.

Pheromonal Control

Some species of Monochamus are attracted to host volatiles and are known to come to traps baited with alpha pinene.

Field Monitoring

Some field monitoring of Monochamus species has been done using traps baited with host attractants. In China, traps baited with alpha pinene have been used to determine whether local populations of Monochamus alternatus are infected with pinewood nematode.

Integrated Pest Management

Integrated pest management of longhorned beetles of the genus Monochamus emphasizes the prevention of attacks (see Cultural Control). In Mexico, avoiding the planting of pine on poor growing sites is recommended to prevent attacks by Monochamus clamator rubigineus (Cibrián Tovar et al., 1995).