Preferred name: Monochamus alternatus
Authority: Hope
Taxonomic position: Animalia: Arthropoda: Hexapoda: Insecta: Coleoptera: Cerambycidae
Other scientific names: Monochamus tesserula White
Common names in English: Japanese pine sawyer
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EPPO Categorization: A1 list
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EPPO Code: MONCAL

Monochamus alternatus is primarily a pest of pines, but it can also attack other plants in the families Pinaceae and Cupressaceae (Davis et al., 2008; Nakamura, 2008; Akbulut et al., 2017; CABI, online). This insect actively attacks Pinus densiflora and P. thunbergii in Japan (Kobayashi et al., 1984; Fauziah et al., 1987; Mamiya 1988; Togashi, 1990a; Anonymous, 2016) and P. massoniana in China (Fan et al., 2007; Li et al., 2007). In laboratory conditions, M. alternatus could infest Japanese cedar (Cryptomeria japonica) (Zhou & Togashi, 2006).

There is also data about M. alternatus infesting deciduous trees: Malus spp. (apple), Fagus spp. (beech), Liquidambar spp. (sweetgum), Ginkgo biloba (maidenhair tree) (Duffy, 1968; Fan & Sun, 2006; Davis et al., 2008; Anonymous, 2016).

Host list: Abies fabri, Abies firma, Abies holophylla, Cedrus deodara, Cedrus libani, Cryptomeria japonica, Cunninghamia lanceolata, Juniperus chinensis, Larix gmelinii, Larix kaempferi, Picea abies, Picea asperata, Picea jezoensis subsp. hondoensis, Picea smithiana, Pinus armandii, Pinus banksiana, Pinus bungeana, Pinus densiflora, Pinus elliottii, Pinus engelmannii, Pinus greggii, Pinus kesiya var. kesiya, Pinus koraiensis, Pinus leiophylla, Pinus luchuensis, Pinus massoniana, Pinus nigra, Pinus oocarpa, Pinus palustris, Pinus parviflora, Pinus pinaster, Pinus ponderosa, Pinus radiata, Pinus rigida, Pinus strobus, Pinus tabuliformis, Pinus taeda, Pinus taiwanensis, Pinus thunbergii, Pinus yunnanensis

M. alternatus is common in several southern Asian countries. This species has been detected many times in wood packaging material imported to Europe (Estonia, Germany, United Kingdom, Denmark, Norway) with cargos from China, but there are no cases of its establishment in the natural environment (Kvamme & Magnusson, 2006; EPPO, 2021).

Asia: China (Anhui, Aomen (Macau), Chongqing, Fujian, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Shaanxi, Shandong, Shanxi, Sichuan, Xianggang (Hong Kong), Xinjiang, Xizhang, Yunnan, Zhejiang), Japan (Hokkaido, Honshu, Kyushu, Ryukyu Archipelago, Shikoku), Korea, Republic, Laos, Taiwan, Vietnam

M. alternatus has 1 to 2 annual generations depending on climatic conditions, mainly linked to mean annual temperatures. M. alternatus spends most of its life within trees. Adults emerge from dead host trees from spring to early autumn, depending on climate, and attack a suitable new host. In Japan, adults emerge from April to August in Okinawa, and in Central Japan from May to August (Ikeda et al., 1980, Kishi, 1995; Akbulut et al., 2017; Futai, 2021). Males emerge before females. The emerging adults are reproductively immature. They fly to conifer host trees and feed on the bark of twigs. This process is referred to as ‘maturation feeding’ and lasts 1-4 weeks (Kishi, 1995; Togashi, 2008; Nakamura, 2008; CABI, online). The duration and extent of maturation feeding is influenced by temperature.

Usually, adults flying from tree to tree can move up to 40 m per week within a host tree stand (Togashi, 1990b, 2008) but it can fly up to 3 km or more in search of a host plant (Kawabata, 1979).

Adults survive 70-125 days under natural conditions and 100 days, on average, under laboratory conditions at a temperature of 25°C (Kobayashi et al., 1984). According to Zhang and Linit (1998), the average life-span of males and females were 70 and 66 days, respectively, in outdoor cages and 180 days in laboratory conditions. 

The development rate of females depends on the quality of the food they consume and the temperature. The ovarian development is faster in females feeding on current year twigs of pine than in females feeding on 1- or 2-year-old twigs. Mating and oviposition occur at night (Katsuyama et al., 1989; Togashi, 2008; Davis et al., 2008).

After maturation feeding and mating females lay eggs. They are attracted to stressed and recently felled trees. The pre-oviposition period depends on daily temperature and usually ranges from 16 to 30 days, although a first oviposition was recorded 6 days after emergence in a warm area of Japan and 61 days in a cool area (Nakamura, 2008).

During oviposition, the female chews a slit in the bark and deposits one egg. It also injects into the slit a gel-like substance (Fauziah et al., 1987; Li & Zhang, 2006). Eggs are usually deposited on host parts with thin bark. Each female lays 60-200 eggs (occasionally more than 200). Oviposition takes place when the air temperature is at least 21.3°C. Egg development requires 65-89 degree days and temperatures above 12.7-13°C (Togashi, 2008; CABI online).

Eggs hatch within 6 to 9 days. During its life cycle, M. alternatus completes four to five larval instars before pupation. Larvae feed on the sapwood and phloem tissues of the host plant and construct galleries that become packed with frass and wood fibres. Larvae overwinter in the galleries. The final larval instar makes a U- or an oval-shaped pupal chamber which usually is plugged with wood borings. The pupal stage lasts 17-19 days, and the callow adult stage lasts 6-8 days. Young adults bore round exit holes and emerge from the wood. A comprehensive description of the biology and ecology of M. alternatus is given in the reviews by Davis et al., 2008, Mota & Vieira (2008), Nakamura (2008), Togashi (2008), EFSA (2020), and Futai (2021).

Symptoms

The mature adults of M. alternatus infest stressed trees, recently felled trees, or logs. External signs of M. alternatus infestation include oviposition scars on the bark and round emergence holes about 9 mm in diameter. Larval feeding produces S-shaped and vertical galleries packed with frass and shredded wood. Larvae also excrete the frass through small slits in the bark that they create. The larvae create U-shaped or oval pupal chambers in the xylem. All life stages of M. alternatus may be found under the bark (Davis et al., 2008; Togashi, 2008; CABI, online). 

Morphology

Egg

Eggs are about 4 mm long, milk white in colour, cylindrical and elongate, sickle shaped. Head capsule highly depressed, about 1.3 times as long as wide.

Larva

Larvae are white, legless, on average 43 mm long when mature, with an amber coloured head capsule and black mouth parts.

Pupa

Pupae are white, opaque and cylindrical, 14 to 27 mm in length. Width 3.6 to 7.2 mm across at the base of elytra.

Adult

Adults are 15-28 mm in length and range from 4.5-9.5 mm wide. Females are larger than males. Males have antennae 2x the body length and females have antennae 1.3x the body length. The base part of the first, second and third antennal segments have greyish hairs. There are two orange stripes on the protergum, interlaced with three narrower black stripes. The elytra have five longitudinal bands of black and grey rectangular spots (Davis et al., 2008).

Detection and inspection methods

The oviposition scars can be found on the bark of the trunk and large branches of dying and felled trees, as well as on logs. Galleries and frass created by larvae are clearly visible when the bark is removed. Another sign is the presence of frass on the bark, which is thrown out by the larvae through the slits. Exit holes which are 9 mm in mean diameter suggest prior infestations and possible presence of life-stages remaining in the wood. Large elliptical holes are visible when cross cutting an infected log. Collection of beetles is also possible using pheromone traps. If it is not possible to identify the specimen by morphological methods, for example for larva, then identification of any life stage is possible using DNA analysis (Shota-Kagaya, 2008).

Usually, the emerging adults populate the nearest pine trees at a distance of up to 100 m, however, the beetles are capable of flying over long distances, up to 2-3 km or more (Togashi, 1990b; Davis et al., 2008; EFSA, 2020). Wind may help the adult flight. Infested logs (non-squared wood) in which all life stages of M. alternatus may be present are a major pathway for spreading the pest. Sawn wood (squared wood) may also contain larvae or pupae of M. alternatus or other longhorn beetles. Most interceptions of M. alternatus in consignments are associated with wood packaging material (Kvamme & Magnusson, 2006; EPPO, 2015a,b, 2016, 2017, 2021). These points are taken into account when developing standards for the movement of wood products, including wood packaging material, in international trade (EPPO, 2018a,b; FAO, 2017, 2019). The development of phytosanitary measures related to trade of wood commodities takes into account the possibility of introduction of both M. alternatus, and the pine wood nematode Bursaphelenchus xylophilus, carried by these beetles and causing pine wilt disease.

Economic impact

M. alternatus attacks stressed trees on which it lays its eggs. Feeding and development of larvae that build galleries in the wood accelerates the tree death and reduces the commercial value of such wood. M. alternatus causes significant damage in Japan, China, and Taiwan, where it is widespread and is the major vector of the pine wood nematode B. xylophilus, the causative agent of the destructive pine wilt disease in Asia. Longhorn beetles transmit nematodes from dead trees to healthy trees during the maturation feeding period. Infection of trees with nematodes under favourable conditions leads to mass death of pine stands within 25 days of adult emergence or by the end of the summer season (Togashi, 1985; Jikumaru & Togashi, 2001). Detailed information on the damage caused by M. alternatus and the pine wood nematode to pine plantations in Asia is given by Mamaya 1988; Zhao, 2008; Soliman et al., 2012; Futai, 2021; CABI (online). The heaviest loss of timber per year by the mutualistic cooperation of M. alternatus and B. xylophilus was recorded as 2.4 million cubic metres in 1979 in Japan (Mamiya, 1988). B. xylophilus has spread from Japan to China, South Korea, Taiwan, Laos and Portugal (Mota et al., 2008; Zhao, 2008; Sousa et al., 2015; Futai, 2021).

The environmental damage caused by M. alternatus is associated with pine wilt disease, which leads to the mass destruction of pine forests. Pine forests provide significant economic and environmental/social benefits for example in terms of the watershed, erosion control, and recreation and pine trees are closely related to the heritage and culture of Japan and China (Zhao, 2008; Futai, 2021). Epidemics of pine wilt result in mass mortality of pine forests and often favour fires.

Control

In areas where M. alternatus and pine wood nematode are common, strategies developed to control pine wilt disease are based primarily on the control of the insect vector. Timely removal of dead or dying trees from the forest to prevent their use as a source for infestation by M. alternatus and the use of insecticides are the basic principles of pest and pine wilt disease control. Silvicultural control through preventive felling and manual removal of dead trees is sometimes more effective in suppressing the spread of pine wilt disease than physical or chemical treatment of wilted pines.

Physical control methods include chipping or burning dead trees infested with M. alternatus. Burying infested wood at a soil depth of more than 15 cm prevents the emergence of adults of M. alternatus. Pheromones and traps play an important role in monitoring and controlling M. alternatus. 

Insecticide application by spraying tree crowns by sprinkler or helicopter during the M. alternatus adult emergence period has shown a high efficacy but has some negative consequences, because it causes mortality of natural enemies and environmental pollution (Kishi, 1995). Injection of nematicides into tree trunks reduced the reproduction rate of M. alternatus (Camata, 2008; CABI, online).  Parasitoid insects (Sclerodermus guani and Dastarcus helophoroides), entomopathogenic fungi (Beauveria bassiana, B. brongniartii, Metarhizium anisopliae, Isaria farinosa, Aspergillus flavus, Verticillium spp., Acremonium sp.), the parasitic bacteria Serratia marcescens and the parasitic nematode, Steinernema feltiae have been used as biological control agents against M. alternatus. The use of the fungus B. bassiana (30 g/ha) to control M. alternatus gave 41.5-69.2% efficiency under field conditions in China. Meanwhile, field tests showed that the application of B. bassiana could reduce the mortality of pine trees caused pine wilt disease by 95.0% (Xu, 2008). Sclerodermus guani is one of the successful natural parasites of M. alternatus larvae. Application of 5 000 Sclerodermus guani wasps to one hectare of woodland showed a parasitism rate of 67-84% on M. alternatus larvae (Xu, 2008).

Phytosanitary risk

The main risk of introduction of M. alternatus is associated with the possibility of introducing this pest together with the pine wood nematode B. xylophilus from countries where this nematode species is present. The risk of introduction both pests into the countries of the EPPO region is high (Evans et al., 2009, EPPO, 2022). Southern EPPO region are most at risk. Eggs, larvae, and pupae can be transported in unprocessed logs. M. alternatus has been detected many times in consignments imported from China to Europe and America (Kvamme & Magnusson, 2006; EPPO, 2015a,b; 2016; 2017; 2021; Anonymous, 2016). Most interceptions were connected with crates, dunnage, and pallets.

Visual inspection of timber does not always reveal the presence of eggs and insect larvae or pupae, which can be present within internal galleries. In this regard, international standards (FAO, 2017; EPPO 2018a,b) have been developed that include phytosanitary measures to prevent the importation of possibly infested wood products. The phytosanitary measures recommended by the EPPO Standard PM 8/2 (3) ‘Coniferae’ (EPPO, 2018b) are considered to be effective against longhorn beetles including M. alternatus. These guidelines include requirements for conifers wood: round wood, sawn wood, and isolated bark. In particular, they require that wood should be bark-free and heat-treated (EPPO, 2008a), or fumigated, or treated with ionizing radiation (EPPO 2008b), or that wood of the host plants from countries where M.alternatus is present should originate from a pest-free area. Requirements for coniferous wood originating from countries where both M. alternatus and B. xylophilus are present are given in the EPPO Standard PM 8/2 (3) (EPPO, 2018b). Wood packaging material should meet the requirements of ISPM no. 15 (FAO, 2019).

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Anonymous (2016) Exotic Wood Borer/Bark Beetle. Monochamus alternatus (Hope). Coleoptera: Cerambycidae. Japanese Pine Sawyer, Survey Reference (Last updated: July 29, 2016). http://download.ceris.purdue.edu/file/3059

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Davis EE, Albrecht EM, Venette RC (2008) Exotic pine pests: survey reference. Monochamus alternatus. CAPS, cooperative agriculture pest survey, 63-74. https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev2_026444.pdf

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EFSA (European Food Safety Authority) Schenk M, Loomans A, Kinkar M, Vos S (2020) Pest survey card on non-European Monochamus spp. EFSA supporting publication EN-1781. 24 pp. https://doi.org/10.2903/sp.efsa.2020.EN-1781

EPPO (2008a) Standard PM 10/6 Heat treatment of wood to control insects and wood-borne nematodes.

EPPO (2008b) Standard PM 10/8 Disinfestation of wood with ionizing radiation.

EPPO (2015a) EPPO Reporting Service No. 4 /080.

EPPO (2015b) EPPO Reporting Service No. 10/195.

EPPO (2016) EPPO Reporting Service No. 2/025. 

EPPO (2017) EPPO Reporting Service No. 6/114. 

EPPO (2018a) PM 9/1 (6) Bursaphelenchus xylophilus and its vectors: procedures for official control. EPPO Bulletin 48, 503-515.

EPPO (2018b) PM 8/2 (3) Coniferae. EPPO Bulletin 48, 463-494.

EPPO (2021) EPPO Reporting Service No. 7/155.

EPPO (2022) Bursaphelenchus xylophilus. EPPO datasheets on pests recommended for regulation. Available online. https://gd.eppo.int/taxon/BURSXY/datasheet

Evans H, Kulinich O, Magnusson C, Robinet C, Schroeder T (2009) Report of a Pest Risk Analysis for Bursaphelenchus xylophilus. 09/15450, 1-17. https://studylib.net/doc/7541927/09-15450

Fan JT, Sun JH (2006) Influences of host volatiles on feeding behaviour of the Japanese pine sawyer, Monochamus alternatus. Journal of Applied Entomology 130, 238-244.

Fan JT, Sun JH, Shi J (2007) Attraction of the Japanese pine sawyer, Monochamus alternatus, to volatiles from stressed host in China. Annals of Forest Science 64, 67-71.

FAO (2017) ISPM 39 International movement of wood Produced by the Secretariat of the International Plant Protection Convention Adopted 2017; published 2017, FAO, Rome, 20 pp

FAO (2019) ISPM 15. Regulation of wood packaging material in international trade. FAO, Rome, 24 pp. https://www.ippc.int/en/publications/640/

Fauziah BA, Hidaka T, Tabata K (1987) The reproductive behavior of Monochamus alternatus Hope (Coleoptera: Cerambycidae). Applied Entomology and Zoology 22, 272-285.

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Ikeda T, Enda N, Yamane A, Oda K, Toyoda T (1980) Attractants for the Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae). Applied Entomology and Zoology 15, 358-361.

Jikumaru S, Togashi K (2001) Transmission of Bursaphelenchus mucronatus (Nematoda Aphelenchoididae) through feeling wounds by Monochamus saltuarius (Coleoptera: Cerambycidae). Nematology 3, 325-333.

Katsuyama N, Sakurai H, Tabatan K, Takeda S (1989) Effect of age of post-feeding twig on the ovarian development of Japanese pine sawyer, Monochamus alternatus. Research Bulletin Faculty of Agriculture, Gifu University 54, 81-89.

Kawabata K (1979) [Dispersal of Monochamus alternatus among small islands]. Transactions of the 32nd Annual Meeting of Kyushu Branch of the Japanese Forestry Society, 281-282 (In Japanese).

Kishi Y (1995) The pine wood nematode and the Japanese pine sawyer. Thomas Company Limited, Tokyo, 302 pp.

Kobayashi F, Yamane A, Ikeda T (1984) The Japanese pine sawyer beetle as the vector of pine wilt disease. Annual Review of Entomology 29, 115-135. 

Kvamme T, Magnusson C (2006) Furuvednematoden -like Aktuell trussel mot Skogen. Norsk Skogbruk 52(7/8), 24- 25.

Li SQ, Zhang ZN (2006) Influence of larval frass extracts on the oviposition behaviour of Monochamus alternatus (Coleoptera: Cerambycidae). Journal of Applied Entomology 130, 177-182.

Li SQ, Fang YL, Zhang ZN (2007) Effects of volatiles of non-host plants and other chemicals on oviposition of Monochamus alternatus (Coleoptera: Cerambycidae). Journal of Pesticide Science 80, 119-123.

Mamiya M (1988) History of pine wilt disease in Japan. Journal of Nematology 20, 219-226.

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Mota M, Vieira P (eds) (2008) Pine Wilt Disease: A worldwide threat to forest ecosystem. Springer, 403 pp.

Nakamura M (2008) Vector-host tree relationships and abiotic environment. In: Pine Wilt Disease (eds. B Zhao, K Futai, J Sutherland, Y Takeuchi) Springer, Japan, 144-162.

Shota-Kagaya (2008) Molecular ecology of vectors. In: Pine Wilt Disease (eds. B.Zhao, K. Futai, J. Sutherland, Y. Takeuchi) Springer, Japan, 162- 184.

Soliman T, Mourits MCM, Werf Wopke van der, Hengeveld GM, Robinet C, Lansink AGJMO (2012) Framework for modeling economic impact of invasive species, applied to pine wood nematode in Europe. PLOS One, 7, N 9. https://doi.org/10.1371/journal.pone.0045505

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Togashi K (1985) Transmission curves of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) from its vector, Monochamus alternatus (Coleoptera: Cerambycidae), in pine trees with reference to population performance. Applied Entomology and Zoology 20, 246-251.

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Togashi K (1990b) A field experiment on dispersal of newly emerged adults of Monochamus alternatus (Coleoptera: Cerambycidae). Population Ecology 32, 1-13.

Togashi K (2008) Vector-nematode relationship and epidemiology in pine wilt disease. In: Pine Wilt Disease (eds. B.Zhao, K. Futai, J. Sutherland, Y. Takeuchi) Springer, Japan, 162- 184.

Xu F (2008) Recent advances in the integrated management of the pine wood nematode in China. In: Pine Wilt Disease (eds. B.Zhao, K. Futai, J. Sutherland, Y. Takeuchi) Springer, Japan, 323- 333.

Zang X, Linit AJ (1998) Comparison of oviposition and longevity of Monochamus alternatus and M. carolinensis (Coleoptera: Cerambycidae) under laboratory conditions. Journal of Nematology 27, 36-41.

Zhao B (2008) Pine wilt disease in China. In: Pine Wilt Disease (eds. B. Zhao, K. Futai, J. Sutherland, Y. Takeuchi) Springer, Japan, 162-184.

Zhou Zu-Ji, Togashi K (2006) Oviposition and larval performance of Monochamus alternatus (Coleoptera: Cerambycidae) on the Japanese cedar Cryptomeria japonica. Journal of Forest Research 11, 35–40. https://doi.org/10.1007/s10310-005-0184-5

CABI and EFSA resources used when preparing this datasheet

CABI Invasive Species Compendium (online) Datasheet report for Monochamus alternatus (Japanese pine sawyer). https://www.cabi.org/isc/datasheet/34719#tocontributors [Accessed: 14 January 2022]

EFSA (European Food Safety Authority) (2020) Schenk M, Loomans A, Kinkar M, Vos S (2020) Pest survey card on non-European Monochamus spp. EFSA supporting publication EN-1781, 24 pp. https://doi.org/10.2903/sp.efsa.2020.EN-1781

This datasheet was prepared in 2022 by Oleg Kulinich [All-Russian Center for Plant Quarantine]. His valuable contribution is gratefully acknowledged.

EPPO (2024) Monochamus alternatus. EPPO datasheets on pests recommended for regulation. https://gd.eppo.int (accessed 2024-12-25)

This datasheet was first published online in 2022. It is maintained in an electronic format in the EPPO Global Database. The sections on 'Identity', ‘Hosts’, and 'Geographical distribution' are automatically updated from the database. For other sections, the date of last revision is indicated on the right.