Preferred name: Dendrolimus sibiricus
Authority: Chetverikov
Taxonomic position: Animalia: Arthropoda: Hexapoda: Insecta: Lepidoptera: Lasiocampidae
Other scientific names: Dendrolimus laricis Chetverikov, Dendrolimus superans sibiricus Chetverikov
Common names in English: Siberian conifer silk moth, Siberian lasiocampid, Siberian moth, Siberian silk moth, larch caterpillar
view more common names online...
Notes on taxonomy and nomenclature EPPO Categorization: A2 list
EU Categorization: A1 Quarantine pest (Annex II A)
view more categorizations online...
EPPO Code: DENDSI

Dendrolimus sibiricus damages conifers from the Pinaceae family (Rozhkov, 1963; Kirichenko & Baranchikov, 2007). Other conifers (Taxaceae and Cupressaceae) are not suitable hosts (Kirichenko et al., 2008). In its native range, D. sibiricus develops practically on all coniferous species of Abies, Pinus, Larix, and Picea (Rozhkov, 1963; Kirichenko & Baranchikov, 2007). In indoor experiments, the pest larvae could develop on European conifer species such as: Abies alba, A. nordmanniana, Larix decidua, Picea abies, Pinus nigra, P. sylvestris (Kirichenko et al., 2008, 2009, 2011). Other potentially suitable hosts, non-native for Europe but grown there for various purposes were the North African Cedrus atlantica ‘Glauca’ and the North American species Abies grandis, Picea sitchensis, Pinus strobus, Pseudotsuga menziesii, and Tsuga canadensis (Kirichenko et al., 2008, 2009).

Larix, Abies, and five-needle pines (Pinus spp.) are the preferred hosts of D. sibiricus both in nature and laboratory tests (Rozhkov, 1963; Kirichenko & Baranchikov, 2007, 2008). Picea is the least suitable host, and the two-needle pines (Pinus sylvestris, P. nigra) are the poorest (Kirichenko & Baranchikov, 2007; Kirichenko et al., 2011). However, during outbreaks, the pest can attack P. sylvestris; for example, damage by D. sibiricus was documented in Transbaikalia in 1990s (Epova, 1999).

Host list: Abies nephrolepis, Abies sibirica, Larix gmelinii, Larix sibirica, Picea jezoensis, Picea koraiensis, Picea obovata, Pinus koraiensis, Pinus sibirica, Pinus sylvestris

The species range covers a large territory of Northeast Asia with a continental climate, reaching the latitudes of 63° north and 40° south and spreading from the coasts of Okhotsk and Sea of Japan (longitude 142°) to Central Russia (around 47°) (Rozhkov, 1963; Kononov et al., 2016; The Federal Service, 2021). The western frontier of D. sibiricus range still remains obscure (Kononov et al., 2016). 

In Russia, the species occurs in Siberia, the Russian Far East, the Ural Mountains and is patchily distributed in Central Russia (Rozhkov, 1963; Boldaruev, 1969). In the Russian Far East, D. sibiricus exists in sympatry with D. superans; in Siberia, Ural Mountains and Central Russia, the range of D. sibiricus largely overlaps with that of D. pini (Kononov et al., 2016). On Sakhalin, the species was initially identified as D. superans albolineatus (Yurchenko & Turova, 2007), but Kononov et al. (2016) examined the specimens collected on the island and identified them as D. sibiricus. In Siberia due to a warming climate, the distribution front moved northward and 300 m higher in mountains compared to that in 20^th century (Kharuk et al., 2017, 2020). In Central Russia, D. sibiricus is known in Permskaya oblast (nearby Ural Mountains) (56°E), Udmurtiya (52°E) and Marii El (47°E) (Rozhkov, 1963; Boldaruev, 1969; Mikkola & Ståhls, 2008; Kononov, 2016; The Federal Service, 2021). In 2001, a few males, originally identified as D. sibiricus, were captured in pheromone traps more than 1000 km to the west, near Moscow (Gninenko & Orlinskii, 2002). However, their taxonomic identification was questioned (Mikkola & Ståhls, 2008), and it is suspected that it was a misidentification of D. pini (Baranchikov et al. 2006). Nevertheless, the low genetic variability discovered in European Russia suggests that the pest is spreading westward (Kononov et al., 2016).

In Kazakhstan, D. sibiricus is found in the northeast (Kalba, Naryn-Kamm, Kürschim-Kamm Riges) (Rozhkov, 1963).

In China, it is known in the northeast (Heilongjiang, Jilin, Liaoning, Neimenggu) (Rozhkov, 1963; Yang & Gu, 1995; Kononov et al., 2016).

In Mongolia, D. sibiricus occurs down to the latitude 40° (Rozhkov, 1963; Boldaruev, 1969; Kononov et al., 2016).

In the Korean Peninsula, the pest is known from the northern part of the Democratic People's Republic of Korea, presumably in Hamgyong province (Rozhkov, 1963; Kononov et al., 2016), and in the Republic of Korea in the provinces of Gangwon and Jeollanam (Jeong et al., 2018).

EPPO Region: Kazakhstan, Russia (Central Russia, Eastern Siberia, Far East, Western Siberia)
Asia: China (Heilongjiang, Jilin, Liaoning, Neimenggu), Kazakhstan, Korea Dem. People's Republic, Korea, Republic, Mongolia

The population dynamics of D. sibiricus is characterized by cycles of slow build-up of population numbers over several years, reaching a peak (an outbreak) followed by a population collapse (Koltunov & Erdakov, 2013). Outbreaks of D. sibiricus occur with a periodicity of 10–12 years (Rozhkov, 1963) or longer time span (depending on the region) (Koltunov & Erdakov, 2013), and they usually last 2–3 years and are often preceded by 2–3 years of hot weather and water deficit during the vegetation season (Rozhkov, 1963; Kondakov, 2002).

In its natural range, D. sibiricus adults emerge from early July up to early August, with males appearing first (Prozorov, 1952). Soon after mating, females start laying eggs on twigs or needles, rarely on bark, mainly in the lower part of tree crowns. During outbreaks, eggs are laid in different parts of the tree crown and on the surrounding ground. An egg mass may contain up to 200 eggs. Each female lays an average of 200–300 eggs (with a maximum of 800) (Rozhkov, 1963; Boldaruev, 1969). Eggs development takes from one to two weeks (20 days maximum) (Rozhkov, 1963; Kirichenko, 2002). After hatching, larvae, consume some or the whole of the egg shell and move to feed on the needles; they gnaw the edges of needles and moult in 7–12 days (Prozorov, 1952; Kirichenko, 2002). At each instar, larvae require more time for development and consume more and more food and, thus, cause more damage to their host trees (Prozorov, 1952; Kirichenko, 2002). In the first year, larvae usually moult up to two times. Third-instar larvae descend to the soil in September and overwinter under the moss. At the end of April to early May of the following year, the larvae return to the crowns and feed on needles. They moult up to two times. In autumn, the larvae of the IV-V instars descend to the soil and overwinter for a second time. In May and June of the following year, the larvae feed very intensively. During this period, they consume about 95% of all food eaten during the whole larval development, and it is during this period that most damage occurs (Rozhkov, 1963; Kirichenko, 2002). In total during their life, larvae moult 5–7 times and have 6–8 instars, correspondingly (Prozorov, 1952; Rozhkov, 1963; Boldaruev, 1969; Kirichenko, 2002). Larvae of I-IV instars benefit from developing in small groups (up to 20 larvae), whereas mature larvae tend to stay apart from each other and, thus, spread within the tree crown (Kirichenko & Baranchikov, 2004). In foci where food is limited, mature larvae can withstand starvation for up to two weeks; during this period, they can disperse from the damaged spot searching for food resource (Prozorov, 1952). 

In June, the larvae spin thick cocoons attaching them to twigs or branches. During outbreaks, mature larvae can pupate on any substrate (tree bark, stems of herbaceous plants etc.) (Rozhkov, 1963). Pupal development takes up to 25 days (Rozhkov, 1963). The full life cycle usually takes two years (Rozhkov, 1963; Boldaruev, 1969), with larvae passing winter in diapause and some undergoing facultative summer diapauses (Kirichenko & Baranchikov, 2002). In southern parts of the natural range, however, one generation can develop in a single year, whereas, in northern regions, the completion of a generation can sometimes take three to four (exceptionally five) years (Rozhkov, 1963; Vinokurov & Isaev, 2002; Kirichenko, 2002).

Symptoms

Defoliation of Abies, Larix, five-needle Pinus, and Picea spp. is usually very spectacular. The presence of larvae in dense populations is easily detected visually, whereas in low density populations, it is necessary to beat trees to check for the presence of larvae (which fall on fabric spread under the tree crown prior to tree beating). The adults are distinguished reliably from related species, in particular from the European D. pini by male genitalia. Adult males can be captured using pheromone traps containing a specific pheromone (Pletnev et al., 2004). However, according to Baranchikov et al. (2006), the synthetic pheromones prepared for D. pini and D. sibiricus attract both species equally well. Only dissection of males and careful examination of their genital structures may allow species identification in such a case (Pet’ko et al., 2004). Eggs laid in clusters can be found on needles, twigs and occasionally on bark (Rozhkov, 1963).

Morphology

Eggs

About 2.2 × 1.9 mm, oval, light-green when laid, turning creamy-white in a few hours, then becoming greyish and finely spotted (Rozhkov, 1963).

Larva

A newly hatched larva is 5-5.5 mm long, mature larva 50–80 mm (exceptionally 88 mm) (Rozhkov, 1963). The body is mainly black or dark-brown with numerous spots and long setae. Behind the 1st and the 2nd thoracic segments and on the VIII abdominal segment, there are clusters of dark blue setae which protect larvae against predators (Rozhkov, 1965). They break off easily and can cause severe eye inflammation, skin dermatoses and arthritis-like disease in humans (Rozhkov, 1965). The 2nd and 3rd thoracic segments are crossed by blue-black stripes; labrum shallowly incised in the middle, epicranium fuscous maculated, in the middle with a pale spot on each side with a yellowish-brown longitudinal stripe; each segment dorsally covered with silvery scales, reflecting a shade of gold, so that in fresh specimens the dorsal hexagonal markings are not distinct; stigma yellowish-white, on its sides with some reddish markings and white scales; dorsal marking of abdominal segments hexagonal. Ventral surface with a series of fuscous spots (Rozhkov, 1963).

Pupa

The pupa is brown, 33–39 mm long in females, 28–34 mm in males, in greyish silk cocoon (Rozhkov, 1963).

Adult

The wingspan is 60–80 mm in females and 40–60 mm in males. The female body length averages 39 mm, and the male 31 mm. The forewing is from light yellowish-brown or light grey to dark brown or almost black; forewings crossed by two characteristic dark stripes; white spot situated at the centre of the forewing; antemedial line to the primaries straight from the costa to the discoidal spot, then becoming oblique, reaches the hind margin at the inner side of the discoidal spot; vein 9 to the primaries opening at the costa and not reaching apex. The postmedial line is much incurved near the costa (Rozhkov, 1963).

The adults of D. sibiricus can spread by flight. In field observations, they flew up to 15 km (Pet’ko, 2004) or up to 50 km (Boldaruev, 1969). Rozhkov (1963) estimated that females may disperse over up to 120 km and males up to 280 km, which, however, needs to be proven by records in nature. All immature stages (eggs, larvae, pupae) can be unintentionally transported on plants moving in trade, particularly plants for planting and cut branches (including Christmas trees). During outbreaks especially, eggs and larvae may be associated with wood carrying bark, or isolated bark, and may be present as contaminating pests on other products.

Economic impact 

Dendrolimus sibiricus is the most important defoliator of conifers (Larix sibirica, Abies sibirica, Pinus sibirica, Picea obovata) in Russia (Rozhkov, 1963; Kondakov, 2002), and one of the most important defoliators of Larix gmelinii in China (Yang & Gu, 1995). Outbreaks occur over enormous areas (many thousands of hectares) and often lead to the death of entire forests (Kondakov, 2002; Fomin et al., 2019). During the last century, at least nine outbreaks were reported in Central Siberia covering the territory of more than 8 million hectares (Kondakov, 2002; Kharuk et al., 2017, 2020). During outbreaks, trees can be defoliated during 2–3 successive years and many of them are unable to withstand such a long period of defoliation (Rozhkov, 1963). Furthermore, the outbreaks of D. sibiricus are often followed by population increase of wood boring insects (scolytids, cerambycids, buprestids and others), particularly Ips acuminatus, I. sexdentatus, I. typographus, I. subelongatus, Monochamus sutor, M. galloprovincialis, M. urussovi, Xylotrechus pilosus, Melanophila guttulata, Buprestis strigosa (Krivets & Chemodanov, 2005; Averenskiy & Isaev, 2011). Some of these insects kill trees stressed by D. sibiricus. Furthermore, severely affected tree stands are predisposed to fires. Reforestation of affected areas is often very complicated and takes much time, resulting in serious ecological and economical losses over large areas (Rozhkov, 1963; Kondakov, 2002).

Control 

Significant control efforts against D. sibiricus, mainly aerial treatment with chemical and bacterial products, are undertaken during outbreaks in Asian Russia (Rozhkov, 1963; Kondakov, 2002; Krivets & Chemodanov, 2005; Yurchenko & Turova, 2007). Various natural enemies: the egg parasitoids Telenomus gracilis, T. tetratomus, Trichogramma dendrolimi, Ooencyrtus pinicolus; the larval parasitoid Rogas dendrolimi, and pupal parasitoids from the Tachinidae family; the microorganisms Bacillus thuringiensis subsp. dendrolimus, Bacillus thuringiensis, Beauveria bassiana, polyhedrosis viruses and some other viruses play an important role in the regulation of the pest population density (Kolomiets, 1962; Rozhkov, 1963, 1965; Boldaruev, 1969; Yurchenko & Turova, 2002).

Phytosanitary risk

Dendrolimus sibiricus is considered to be a very serious defoliator of coniferous forests in the areas where it occurs and is likely to be able to establish in further EPPO countries, particularly those in the north. It is very likely that D. sibiricus, which has a wide host range within the Pinaceae family in its native range, will be able to attack other species of the same genera in the western part of the EPPO region, where they are important forest and amenity trees. It is likely that it will also be able to attack tree species from genera that are absent from its native range, but which have been shown to be highly suitable hosts in experiments, such as Pseudotsuga, Tsuga, Cedrus.

Dendrolimus sibiricus was added in 2002 to the EPPO A2 list, and endangered EPPO member countries are thus, recommended to regulate it as a quarantine pest. The species seems to be slowly spreading westwards, and it is important to conduct surveys using pheromone traps in areas at the border of its present range (Pletniev et al., 1999) in order to achieve early detection and timely apply control measures to contain or eradicate it.

To prevent the introduction of D. sibiricus by international movement of commodities, plants for planting and cut branches of host plants from the infested areas should be free from soil according to FAO (2017). Such commodities should originate from pest-free areas, or produced under physical protection, or imported during winter. Wood should be debarked or heat-treated, or originate in a pest-free area, or be also imported during winter (EPPO, 2018).

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Fomin SN, Barinov VV & Myglan VS (2019) [Siberian silkmoth in the Republic of Tuva, the history of studies]. Sibirskii Lesnoi Zurnal no. 5, 3-14 (in Russian with English abstract).

Gninenko Y & Orlinskii AD (2002) Dendrolimus sibiricus in the coniferous forests of European Russia at the beginning of the twenty-first century. EPPO Bulletin 332, 481-483.

Jeong JS, Kim MJ, Kim SS, Choi SW & Kim I (2018) DNA data and morphology suggest an occurrence of Dendrolimus sibiricus Tschetverikov, 1908 (Lepidoptera: Lasiocampidae) instead of D. superans Butler, 1877, in South Korea. Entomological Research 48, 108-121.

Kharuk VI, Im ST, Ranson KJ & Yagunov MI (2017) Climate-induced northerly expansion of Siberian silkmoth range. Forests 8, 301, 1–9.

Kharuk VI, Im ST & Soldatov VV (2020) Siberian silkmoth outbreaks surpassed geoclimatic barrier in Siberian Mountains. Journal of Mountain Science 17, 1891-1900.

Kirichenko N, Flament J, Baranchikov Yu, Grégoire J-C (2011) Larval performances and life cycle completion of the Siberian moth, Dendrolimus sibiricus (Lepidoptera: Lasiocampidae), on potential host plants in Europe: a laboratory study on potted trees. European Journal of Forest Research 130(6), 1067-1074.

Kirichenko NI & Baranchikov YuN (2004) Changes of density optimum in the ontogenesis of larvae of Siberian moth Dendrolimus superans sibiricus (Lepidoptera, Lasiocampidae). Entomological Review [Zoologicheskii Zhurnal] 84, 256-271.

Kirichenko NI & Baranchikov YuN (2002) Feeding and growth of caterpillars of the Siberian moth Dendrolimus superans sibiricus (Lepidoptera. Lasiocampidae) during summer diapause. Entomological Review [Zoologiskii Zhurnal] 82, 1084-1089.

Kirichenko NI & Baranchikov YuN (2007) Appropriateness on needles of different conifer species for the feeding and growth of larvae from two populations of the Siberian moth. Russian Journal of Ecology [Ekologiya] 38, 216-221.

Kirichenko NI & Baranchikov YuN, Vidal S (2009) Host plant preference and performance of the potentially invasive Siberian moth (Dendrolimus superans sibiricus) on European coniferous species. Agricultural and Forest Entomology 11, 247-254.

Kirichenko NI, Flament J, Baranchikov YuN & Grégoire J-C (2008) Native and exotic coniferous species in Europe – possible host plants for the potentially invasive Siberian moth, Dendrolimus sibiricus Tschtv. (Lepidoptera, Lasiocampidae). EPPO Bulletin 38, 259-263.

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Kononov A, Ustyantsev K, Wang B, Mastro VC, Fet V, Blinov A & Baranchikov Yu (2016) Genetic diversity among eight Dendrolimus species in Eurasia (Lepidoptera: Lasiocampidae) inferred from mitochondrial COI and COII, and nuclear ITS2 markers. BMC Genetics 17(157), 174-191.

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The Federal Service for Veterinary and Phytosanitary Supervision in the Nizhny Novgorod Region and the Republic of Marii El (2021) In 7 districts of the Republic of Mari El, the Siberian silkworm quarantine is maintained! The news from 30.09.2021. http://www.ursn-nnov.ru/ru/news/?nid=18422&a=entry.show (last accessed 2021-12-17)

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This datasheet was extensively revised in 2022 by Dr Natalia Kirichenko [Sukachev Institute of Forest, the Siberian Branch of the Russian Academy of Sciences, Federal Research Center ‘Krasnoyarsk Science Center SB RAS’ and Siberian Federal University, Krasnoyarsk, Russia]. Her valuable contribution is gratefully acknowledged.

EPPO (2024) Dendrolimus sibiricus. EPPO datasheets on pests recommended for regulation. https://gd.eppo.int (accessed 2024-04-26)

This datasheet was first published in the EPPO Bulletin in 2005 and revised in 2022. It is now 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.

EPPO (2005) Data sheets on quarantine pests. Dendrolimus sibiricus and Dendrolimus superans. EPPO Bulletin 35(3), 390-395. https://doi.org/10.1111/j.1365-2338.2005.00878.x