Flø et al. Forest Ecosystems (2020) 7:48 https://doi.org/10.1186/s40663-020-00258-9 REVIEW Open Access The Siberian moth (Dendrolimus sibiricus), a pest risk assessment for Norway Daniel Flø1,2* , Trond Rafoss1,2, Michael Wendell2 and Leif Sundheim1 Abstract Background: The Siberian moth (Dendrolimus sibiricus) is a serious pest of conifers in Russia, Northern Kazakhstan, Mongolia and China. The western border of the pest’s distribution in Russia is disputed, but it is present west of the 60th meridian east. The pest has the potential to defoliate a wide range of conifers. Results: The pest is not present in Norway or other European countries, except Russia. Natural spread and human mediated transport are potential pathways for the pest. Human mediated pathways considered are: Living trees for planting, coniferous wood in the rough and foliage and branches. There has been no import of living trees from Russia to Norway during the past 30 years, and there is currently no import of coniferous wood commodities containing bark from areas, where D. sibiricus occurs. Conclusions: The probability of D. sibiricus entry by natural spread is unlikely, mainly because of the geographical distance and the partial sea barriers between Norway and the infested areas. The probability of entry by human mediated pathways is unlikely due to the very limited volume of the import. Should the pest enter Norway, the probability of establishment and spread is unlikely, due to the suboptimal climatic conditions, and the fact that the two dominant conifers in the country, Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), are intermediate and poor hosts, respectively. The potential damage, should D. sibiricus enter Norway, is considered low. Keywords: Lepidoptera, Invasive species, Geographical distribution, Forest pest Background million ha of pine forest near the Ket and Chulym rivers, The Siberian lappet moth Dendrolimus sibiricus Chet- both of which are South-West Siberian tributaries of the verikov 1908 is closely related to the pine-tree lappet Ob river (Kharuk et al. 2016). During the years 1932 to moth Dendrolimus pini L 1758, which is present in 1957, the pest infested 7 million hectares of pine forest and Norway and the rest of Europe. Dendrolimus sibiricus is damaged 50% of the trees in western Siberia and in the the most destructive pest of conifers in Russia, parts of Chita Oblast, South-East Siberia (Baranchikov and Mont- Northern Kazakhstan, Mongolia and China (EPPO gomery 2014). The exact geographical distribution of D. 2005). In an area stretching from the Pacific Ocean, sibiricus remains obscure, as the alleged westward expan- across Russia and past the Ural Mountains conifers are sion towards Moscow (Gninenko and Orlinskii 2002)has infested with D. sibiricus (Fig. 1). During the period been questioned (Mikkola and Stahls 2008)andthoughtto 1994–96 D. sibiricus damaged 700.000 ha of pine forest be based on a misidentification of D. pini as D. sibiricus in Krasnoyarsk krai, Central Siberia (Zhirin et al. 2016). (Baranchikov et al. 2006). The Norwegian Scientific Com- Between 1954 and 1957, the pest damaged over 1.5 mittee for Food and Environment in 2018 published a Pest Risk Assessment of D. sibiricus (Rafoss et al. 2018). * Correspondence: [email protected] 1 Norwegian Institute of Bioeconomy Research, Høgskoleveien 7, 1433 Ås, Biology of the pest Norway 2The Norwegian Scientific Committee for Food and Environment, Dendrolimus sibiricus is an arthropod in the family Sandakerveien 24 C, 0473 Oslo, Norway Lasiocampidae of the order Lepidoptera. Adults of D. © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Flø et al. Forest Ecosystems (2020) 7:48 Page 2 of 11 Fig. 1 Map of Russia showing the federal subjects, where Dendrolimus sibiricus is present (dark gray areas) and not present (light gray areas). The distribution of D. sibiricus is uncertain for some of the federal subjects in European Russia (gray areas). The black lines represent the distribution for some of the main host species for D. sibiricus. The 60th meridian east represents the border between Europe and Asia. The map was compiled from literature and personal communication. Data on the distribution of Picea obovata were unavailable sibiricus fly from the end of June to the beginning of potentially resulting in severe damage to large forest August, and each female can lay up to 800 eggs (length areas. 1.9–2.2 mm) on the bark of stems and branches and on needles of host trees (EPPO 2005). Larvae (length 60–82 Host plants of the pest in the PRA area mm) hatch after 13 to 22 days and start feeding on the nee- Picea abies (L.) H. Karst. and Pinus sylvestris L. are the dles. Overwintered larvae make cocoons during the period dominant conifers in Norwegian forests. A larval host plant June to late July and pupate (pupae 50–110 mm in length) bioassay showed that D. sibiricus larvae are able to develop in the trees. The life cycle typically takes from 1 to 2 years, on the main European coniferous hosts (Kirichenko et al. depending on population density and temperature. Larvae 2009). However, P. abies and P. sylvestris are intermediate may have between six and eight instars, and diapausing lar- and poor hosts for D. sibiricus larvae, respectively. On vae survive one or two winters in the ground, in litter or these hosts larvae development time increased, and larvae underneath moss. However, parts of the larval population mortality reached 14.5% on P. abies and 66.7% on P. sylves- can enter summer diapause (a period of slow development tris, compared to 3.2% mortality on Larix decudia Mill., of the third to fifth instar larvae), if food availability is low which had the lowest larvae mortality in the experiment or abiotic conditions are unfavourable, prolonging their life (Kirichenko et al. 2009). In Norway, the main hosts of D. cycle up to 4 years (Kirichenko et al. 2011). Due to this sibiricus (A. sibirica, L. sibirica, P. obovata and P. sibirica) prolonged diapause, parts of the population may have a life are planted only on a very small scale, mostly in mountain cycle of either 2, 3 or 4 years, which contributes to the forests and in the north of the country (Elven 2005). These population persistence during unfavourable conditions. hosts are not considered further in this assessment. Host plants of the pest Geographical distribution of the pest Dendrolimus sibiricus larvae only infest coniferous trees. Dendrolimus sibiricus is native to Russia and restricted Hardin and Suazo (2012) presented an extensive list of parts of northern Kazakhstan, Mongolia and China (EPPO reported host plant species for D. sibiricus. The main 2005). The pest is present west of the 60th meridian in hosts are Siberian fir (Abies sibirica Gordon), Siberian European Russia. However, the exact western border of D. larch (Larix sibirica Ledeb.), Siberian spruce (Picea obo- sibiricus geographical distribution is disputed among ex- vata Ledeb.) and Siberian pine (Pinus sibirica Du Tour). perts Gninenko and Orlinskii (2002), Kirichenko et al. Kirichenko et al. (2009) concluded that D. sibiricus is (2009), Kononov et al. (2016). The alleged westward expan- able to develop on the main European coniferous hosts, sion towards Moscow Gninenko and Orlinskii (2002)has Flø et al. Forest Ecosystems (2020) 7:48 Page 3 of 11 been questioned (Mikkola and Ståhls 2008), and thought However, due to limited import of relevant coniferous to be based on a misidentification of D. pini as D. sibiricus commodities to Poland, the probability of introduction (Baranchikov et al. 2006). The northern limit of the pest is was considered low (Kubasik et al. 2017). uncertain, but according to Rozkov (1963)thecityofYa- A Pest Categorization of D. sibiricus by EFSA Panel on kutsk, 450 km south of the Arctic Circle in East Siberia, is Plant Health (EFSA 2018) stated that the previous the northernmost record of the species. However, there are contradictory studies regarding the climatic require- uncertainties as to which data Rozkov (1963) used for his ments of D. sibiricus make the issue of its establishment map. Therefore, D. sibiricus could be more widespread in in most of Europe uncertain, although the host plants Northern Russia than previously reported (Flament et al. are widely present. All criteria for considering D. sibiri- 2013). Also, there are uncertainties as to the southern cus a potential quarantine pest are met, but the pest is limits for the distribution of the pest in China, Mongolia presently absent from EU, and the criteria for consider- and Kazakhstan. Therefore, the distribution of the main ation as a potential regulated, non-quarantine pest are hostsinAsiamaybethebestindicatorofthehistoricdis- not met (EFSA 2018). tribution of D. sibiricus (Fig. 1). Identification of human mediated pathways for entry Regulatory status of the pest The potential pathways for entry of D. sibiricus are by Dendrolimus sibiricus is not regulated in the PRA area, human mediated spread and by natural spread.