Japanese Pine Sawyer | Monochamus alternatus (Hope)

California Pest Rating  for
Japanese Pine Sawyer | Monochamus alternatus (Hope)
Coleoptera: Cerambycidae
Pest Rating: A



Initiating Event:

Monochamus alternatus is currently Q-rated.  A permanent pest rating proposal is required to support an official pest rating.

History & Status:

Background:  Monochamus alternatus is a large (1.5-3 cm in length) beetle that is orange-brown with gray and black markings on the elytra and black stripes on the pronotum (Benker, 2012).  The eggs are laid in dead or dying coniferous trees, primarily Pinus species but also Abies, Cedrus, Larix, and Picea species (Benker, 2012).  The larvae feed on the wood and pupate inside the host.  Adults feed on living branches of healthy pines before mating.  This pre-reproduction feeding is common in Cerambycidae and is referred to as maturation feeding (Shibata, 1984).  Monochamus alternatus is a vector of the pine wood nematode or pine wilt nematode, Bursaphelenchus xylophilus (Steiner and Buhrer), which causes pine wilt disease, a deadly disease of pines (Kwon et al., 2006; Shibata, 1984).  The nematode is transmitted to healthy trees during maturation feeding, and if the tree is susceptible, pine wilt disease ensues.  The nematodes are also transferred to dead trees during oviposition.  Nematodes that are present in the dead trees while the beetle is developing are then dispersed with the emerging adult beetle to be transmitted to healthy trees during maturation feeding.  This nematode is native to North America and appears to cause little damage there, although exotic pines are also attacked (Donald et al., 2016).  The nematode has been introduced to the Old World and has had a severe impact in Asia.

Cerambycids that feed on dead wood, including Monochamus species, can damage cut timber through the tunneling and feeding of the larvae and the staining of the wood by fungi that enter the wood through feeding damage (Raske, 1972).  Monochamus species were reported to be some of the most common pests of wood in mill yards in British Columbia, and the tunneling of their larvae significantly degraded the value of timber (Carlson, 1997).

Worldwide Distribution:  Monochamus alternatus is present in China, Korea, Japan, Laos, Taiwan, and Vietnam (Kwon et al., 2006).

Official Control: Monochamus alternatus is categorized as an “A1” pest by the EPPO, a quarantine pest by Canada and Norway, and reportable by the USDA-APHIS (EPPO, 2018; USDA-APHIS).

California Distribution:  Monochamus alternatus is not known to be present in California (Symbiota Collections of Arthropods Network).

California Interceptions:  Monochamus alternatus was found in a store in Sacramento County, apparently having emerged from wood crates from China, in 2005.  The species was also found on wood crates from China in Santa Clara County in 1995, although this identification was tentative (CDFA Pest and Damage Report Database, 2018).

The risk Monochamus alternatus would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: The climates represented by the distribution of Monochamus alternatus apparently range from tropical to temperate. In one experiment, the survival of the beetle at low temperatures led the authors to suggest -10°C January mean air temperature as the lower limit of survival (Ma et al., 2006).  The majority of California has higher mean January temperatures than this (National Oceanic and Atmospheric Administration, 2018).  This beetle is reported to feed on trees in the genera Pinus, Abies, Cedrus, Larix, and Picea.  Except for Larix, there are numerous native and introduced species from these genera in California, and they are distributed widely within the state.  Monochamus alternatus could become established in a large portion of California.  Therefore, Monochamus alternatus receives a High (3) in this category.

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.

– Medium (2) may be able to establish in a larger but limited part of California.

– High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: Monochamus alternatus is reported to feed on five genera in the family Pinaceae. Therefore, it receives a Medium (2) in this category.

– Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

3) Pest Dispersal Potential: Monochamus alternatus can fly (Ito, 1982), and is also capable of being dispersed through movement of wood, as shown by the interception of this species in wood packing material.  Therefore, it receives a Medium (2) in this category.

– Low (1) does not have high reproductive or dispersal potential.

– Medium (2) has either high reproductive or dispersal potential.

– High (3) has both high reproduction and dispersal potential.

4) Economic Impact: If alternatus became established in California, it could damage cut timber, which would reduce the value of the timber.  The timing of timber harvest may be changed in response to this.  This beetle is a known vector of the pine wood nematode, which is present in California and damages and kills introduced pines.  Therefore, it receives a High (3) in this category.

Economic Impact:  B, D, E

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

Economic Impact Score:  3

– Low (1) causes 0 or 1 of these impacts.

– Medium (2) causes 2 of these impacts.

– High (3) causes 3 or more of these impacts.

5) Environmental Impact: Monochamus alternatus is a known vector of pine wood nematode, which is present in California. This nematode apparently does not impact native pines, but it damages and kills introduced pines, so plantings of introduced pines in California would be threatened by the establishment of this beetle.  Therefore, it receives a Medium (2) in this category.

Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact:  E

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Environmental Impact Score:  2

– Low (1) causes none of the above to occur.

– Medium (2) causes one of the above to occur.

– High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Monochamus alternatus: Medium (12)

Add up the total score and include it here.

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Monochamus alternatus is not known to be present in California.  It receives a Not established (0) in this category.

–Not established (0) Pest never detected in California, or known only from incursions.

–Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

–Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

–High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (12)


There is some uncertainty regarding the potential for M. alternatus to impact living trees.  Such concerns, however, are based on the biology reported for other Monochamus species, and may not apply to M. alternatus.  Maturation feeding by other Monochamus species is reported to injure trees and make them susceptible to other pests (Ethington, 2015; Ross et al., 1991).  Other Monochamus species are also reported to lay eggs on living trees, although this often occurred during field experiments that involved attracting the beetles to trees with pheromones, so the conditions may not have been realistic.  In addition, larval survival in such cases appears to be low, apparently because the living trees resisted the attacks with resin flow (Ethington, 2015; Ethington et al., 2015).  Lastly, there is the possibility that M. alternatus could bring other pests with it to California and transmit them to living trees during maturation feeding.  For example, there is a native Asian species of Bursaphelenchus that occurs in pines.  This nematode could have a more significant impact on pines in North America if it became established here, similar to how the pine wood nematode is a serious problem in Asia but not in North America (where it is native) (Van Driesche et al., 2013).  Any one of these (potential for adult or larval feeding to impact living trees and potential for carrying and vectoring nematodes or other plant pathogens not present in California) could increase the risk that M. alternatus poses to California.

Conclusion and Rating Justification:

Monochamus alternatus is a wood-boring beetle that is not known to be present in California.  The species belongs to a genus that is known to cause significant damage to timber.  In addition, M. alternatus vectors an important pine pest, pine wood nematode, and although this nematode is already present in California, this beetle could possibly carry with it other plant pathogens (including nematodes) not yet present in California.  This beetle poses an economic and environmental threat to California.  For these reasons, an “A” rating is justified.


Benker, U.  2012.  Monochamus alternatus – The next alien causing trouble.  Forstschutz Aktuell 55:34-37.

CDFA Pest and Damage Report Database.  2018.  Monochamus alternatus.  Plant Health and Pest Prevention Services. CA Department of Food and Agriculture.  Accessed April 18, 2018: https://pdr.cdfa.ca.gov/PDR/pdrmainmenu.aspx

Carlson, J. A.  1997.  Damage assessment of wood borers in the interior of B.C.  Forest Renewal BC Research Program.

Donald, P. A., Stamps, W. T., Linit, M. J., and Todd, T. C.  2016.  Pine wilt disease.  Accessed April 18, 2018: https://www.apsnet.org/edcenter/intropp/lessons/Nematodes/Pages/PineWilt.aspx

EPPO.  2018.  EPPO global database.  Accessed April 23, 2018:  https://gd.eppo.int/taxon/MONCAL/categorization

Ethington, M.  2015.  Southeastern Monochamus and their interactions with healthy shortleaf pine trees and associated Ips grandicollis bark beetles.  M.S. thesis. University of Arkansas.

Ethington, M., Galligan, L., Wakarchuk, D., and Stephen, F.  2015.  Can pheromones and host volatiles induce Monochamus species (Cerambycidae: Lamiinae) to colonize healthy shortleaf pines?  Accessed April 24, 2018: https://www.researchgate.net/publication/275273308_Can_pheromones_and_host_volatiles_induce_Monochamus_species_Cerambycidae_Lamiinae_to_colonize_healthy_shortleaf_pines

Ito, K.  1982.  The tethered flight of the Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae).  Journal of the Japanese Forest Society 64:395-397.

Kwon, T.- S., Lim, J.- H., Sim, S.- J., Kwon, Y.- D., Son, S.- K., Lee, K.- Y., Kim, Y.- T., Park, J.- W., Shin, C.- H., Ryu, S.- B., Lee, C.- K., Shin, S.- C., Chung, Y.- J., and Park, Y.- S.  2006.  Distribution patterns of Monochamus alternatus and M. saltuarius (Coleoptera: Cerambycidae) in Korea.  Journal of Korean Forest Society 95:543-550.

Ma, R.- Y., Hao, S.- G., Kong, W.- N., Sun, J.- H., and Kang, L.  2006.  Cold hardiness as a factor for assessing the potential distribution of the Japanese pine sawyer Monochamus alternatus (Coleoptera: Cerambycidae) in China.  Annals of Forest Science 63:449-456.

National Oceanic and Atmospheric Administration.  2018.  National Centers for Environmental Information.  Accessed April 20, 2018: https://www.ncdc.noaa.gov/

Raske, A. G.  1972.  Biology and control of Monochamus and Tetropium, the economic wood borers of Alberta (Coleoptera: Cerambycidae).  Northern Forest Research Centre Internal Report NOR-9:1-48.

Ross, D., Johnson, K., and Hilburn, D.  1991.  Siberian forest pests of concern in wood.  pp. I-50-I-54 in U.S.D.A. Forest Service (ed.), Pest Risk Assessment of the Importation of Larch from Siberia and the Soviet Far East. United States Department of Agriculture Forest Service.

Shibata, E.  1984.  Spatial distribution pattern of the Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae), on dead pine trees.  Applied Entomology and Zoology 19:361-366.

Symbiota Collections of Arthropods Network.  Accessed April 18, 2018: http://scan1.acis.ufl.edu

USDA-APHIS.  2018.  U.S. regulated plant pest table.  Accessed April 23, 2018:  https://www.aphis.usda.gov/aphis/ourfocus/planthealth/import-information/rppl/rppl-table

Van Driesche, R. G., LaForest, J. H., Bargeron, C. T., Reardon, R. C., and Herlihy, M.  2013.  Forest Pest Insects in North America: A Photographic Guide.  Accessed: June 7, 2018 https://www.fs.fed.us/foresthealth/technology/pdfs/Forest_Pest_Insects_Photo_Guide_508.pdf


Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741; plant.health[@]cdfa.ca.gov.

Responsible Party:

Jason Leathers, 2800 Gateway Oaks, Sacramento CA 95833, (916) 654-1211, plant.health[@]cdfa.ca.gov

Comment Period:* CLOSED

6/28/18 – 8/12/18


You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.

Comment Format:

♦  Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

Example Comment:
Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

♦  Posted comments will not be able to be viewed immediately.

♦  Comments may not be posted if they:

Contain inappropriate language which is not germane to the pest rating proposal;

Contains defamatory, false, inaccurate, abusive, obscene, pornographic, sexually oriented, threatening, racially offensive, discriminatory or illegal material;

Violates agency regulations prohibiting sexual harassment or other forms of discrimination;

Violates agency regulations prohibiting workplace violence, including threats.

♦  Comments may be edited prior to posting to ensure they are entirely germane.

♦  Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.

Pest Rating: A


Posted by ls