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Pest categorisation of Dendrolimus sibiricus

Abstract The Panel on Plant Health performed a pest categorisation of the Siberian moth, Dendrolimus sibiricus Tschetverikov (Lepidoptera: Lasiocampidae). D. sibiricus is a well‐defined and distinguishable species, native to Asian Russia and northern regions of Kazakhstan, Mongolia, China and North Korea, and recognised as a severe pest of Pinaceae conifers, mainly larch (Larix spp.), fir (Abies spp.), spruce (Picea spp.), five‐needle pines (Pinus spp.). It has also a potential to develop on non‐native Pinaceae: Cedrus, Pseudotsuga, Tsuga. It defoliates healthy trees and kills thousands of hectares of forests. It is absent from the EU and is listed as a quarantine pest in Annex IAI of Directive 2000/29/EC. Plants for planting, branches of conifers and non‐squared wood from its distribution range are considered as pathways for the pest, which can also disperse by flight over tens of kilometres. The females produce sex pheromones. Adults do not feed and can survive for about 2 weeks. One female lays up to 400 eggs, attaching them to needles. One generation usually develops in 2–3 years, with larvae passing winter diapause and some undergoing facultative summer diapause. Exceptionally, 1‐year generations may occur if the number of degree‐days above 10°C is higher than 2,200. Larvae feed on needles through 5–6 instars and pupate in a cocoon on tree branches. Mature larvae have urticating setae on thoracic segments that protect them from enemies and may cause allergic reactions in humans and animals. The contradictory studies regarding the climatic requirements of D. sibiricus make the issue of its establishment in most of the EU territory uncertain, although its host trees are widely present. All criteria for considering D. sibiricus as a potential quarantine pest are met. The species is presently absent from the EU, and thus, the criteria for consideration as a potential regulated non‐quarantine pest are not met.


. Background
Council Directive 2000/29/EC 1 on protective measures against the introduction into the Community of organisms harmful to plants or plant products and against their spread within the Community establishes the present European Union plant health regime. The Directive lays down the phytosanitary provisions and the control checks to be carried out at the place of origin on plants and plant products destined for the Union or to be moved within the Union. In the Directive's 2000/29/EC annexes, the list of harmful organisms (pests) whose introduction into or spread within the Union is prohibited, is detailed together with specific requirements for import or internal movement.
Following the evaluation of the plant health regime, the new basic plant health law, Regulation (EU) 2016/2031 2 on protective measures against pests of plants, was adopted on 26 October 2016 and will apply from 14 December 2019 onwards, repealing Directive 2000/29/EC. In line with the principles of the above mentioned legislation and the follow-up work of the secondary legislation for the listing of EU regulated pests, EFSA is requested to provide pest categorizations of the harmful organisms included in the annexes of Directive 2000/29/EC, in the cases where recent pest risk assessment/pest categorisation is not available.

Terms of Reference
EFSA is requested, pursuant to Article 22(5.b) and Article 29(1) of Regulation (EC) No 178/2002 3 , to provide scientific opinion in the field of plant health.
EFSA is requested to prepare and deliver a pest categorisation (step 1 analysis) for each of the regulated pests included in the appendices of the annex to this mandate. The methodology and template of pest categorisation have already been developed in past mandates for the organisms listed in Annex II Part A Section II of Directive 2000/29/EC. The same methodology and outcome is expected for this work as well.
The list of the harmful organisms included in the annex to this mandate comprises 133 harmful organisms or groups. A pest categorisation is expected for these 133 pests or groups and the delivery of the work would be stepwise at regular intervals through the year as detailed below. First priority covers the harmful organisms included in Appendix 1, comprising pests from Annex II Part A Section I and Annex II Part B of Directive 2000/29/EC. The delivery of all pest categorisations for the pests included in Appendix 1 is June 2018. The second priority is the pests included in Appendix 2, comprising the group of Cicadellidae (non-EU) known to be vector of Pierce's disease (caused by Xylella fastidiosa), the group of Tephritidae (non-EU), the group of potato viruses and virus-like organisms, the group of viruses and virus-like organisms of Cydonia Mill., Fragaria L., Malus Mill., Prunus L., Pyrus L., Ribes L., Rubus L. and Vitis L.. and the group of Margarodes (non-EU species). The delivery of all pest categorisations for the pests included in Appendix 2 is end 2019. The pests included in Appendix 3 cover pests of Annex I part A section I and all pests categorisations should be delivered by end 2020.
For the above mentioned groups, each covering a large number of pests, the pest categorisation will be performed for the group and not the individual harmful organisms listed under "such as" notation in the Annexes of the Directive 2000/29/EC. The criteria to be taken particularly under consideration for these cases, is the analysis of host pest combination, investigation of pathways, the damages occurring and the relevant impact.
Finally, as indicated in the text above, all references to 'non-European' should be avoided and replaced by 'non-EU' and refer to all territories with exception of the Union territories as defined in Article 1 point 3 of Regulation (EU) 2016/2031.

Interpretation of the Terms of Reference
Dendrolimus sibiricus is one of a number of pests listed in the Appendices to the Terms of Reference (ToR) to be subject to pest categorisation to determine whether it fulfils the criteria of a quarantine pest or those of a regulated non-quarantine pest for the area of the European Union (EU) excluding Ceuta, Melilla and the outermost regions of Member States (MSs) referred to in Article 355(1) of the Treaty on the Functioning of the European Union (TFEU), other than Madeira and the Azores.

2.
Data and methodologies 2.1. Data 2.1.1. Literature search A literature search on D. sibiricus was conducted at the beginning of the categorisation in the ISI Web of Science bibliographic database, using the scientific name of the pest as search term. Relevant papers were reviewed and further references and information were obtained from experts, as well as from citations within the references and grey literature.

Database search
Pest information, on host(s) and distribution, was retrieved from the European and Mediterranean Plan Protection Organization (EPPO) Global Database (EPPO, 2018) and relevant publications.
Data about the import of commodity types that could potentially provide a pathway for the pest to enter the EU were obtained from EUROSTAT (Statistical Office of the European Communities).
The Europhyt database was consulted for pest-specific notifications on interceptions and outbreaks. Europhyt is a web-based network run by the Directorate General for Health and Food Safety (DG SANT E) of the European Commission, and is a subproject of PHYSAN (Phyto-Sanitary Controls) specifically concerned with plant health information. The Europhyt database manages notifications of interceptions of plants or plant products that do not comply with EU legislation, as well as notifications of plant pests detected in the territory of the MSs and the phytosanitary measures taken to eradicate or avoid their spread.

Methodologies
The Panel performed the pest categorisation for D. sibiricus, following guiding principles and steps presented in the EFSA guidance on the harmonised framework for pest risk assessment (EFSA PLH Panel, 2010) and as defined in the International Standard for Phytosanitary Measures No 11 (FAO, 2013) and No 21 (FAO, 2004).
In accordance with the guidance on a harmonised framework for pest risk assessment in the EU (EFSA PLH Panel, 2010), this work was initiated following an evaluation of the EU plant health regime. Therefore, to facilitate the decision-making process, in the conclusions of the pest categorisation, the Panel addresses explicitly each criterion for a Union quarantine pest and for a Union regulated nonquarantine pest in accordance with Regulation (EU) 2016/2031 on protective measures against pests of plants, and includes additional information required in accordance with the specific terms of reference received by the European Commission. In addition, for each conclusion, the Panel provides a short description of its associated uncertainty. Table 1 presents the Regulation (EU) 2016/2031 pest categorisation criteria on which the Panel bases its conclusions. All relevant criteria have to be met for the pest to potentially qualify either as a quarantine pest or as a regulated non-quarantine pest. If one of the criteria is not met, the pest will not qualify. A pest that does not qualify as a quarantine pest may still qualify as a regulated nonquarantine pest that needs to be addressed in the opinion. For the pests regulated in the protected zones only, the scope of the categorisation is the territory of the protected zone; thus, the criteria refer to the protected zone instead of the EU territory.
It should be noted that the Panel's conclusions are formulated respecting its remit and particularly with regard to the principle of separation between risk assessment and risk management (EFSA founding regulation (EU) No 178/2002); therefore, instead of determining whether the pest is likely to have an unacceptable impact, the Panel will present a summary of the observed pest impacts. Economic impacts are expressed in terms of yield and quality losses and not in monetary terms, whereas addressing social impacts is outside the remit of the Panel, in agreement with EFSA guidance on a harmonised framework for pest risk assessment (EFSA PLH Panel, 2010). Is the identity of the pest established, or has it been shown to produce consistent symptoms and to be transmissible?
Is the identity of the pest established, or has it been shown to produce consistent symptoms and to be transmissible?
Is the identity of the pest established, or has it been shown to produce consistent symptoms and to be transmissible?
Absence/ presence of the pest in the EU territory (Section 3.2) Is the pest present in the EU territory? If present, is the pest widely distributed within the EU? Describe the pest distribution briefly! Is the pest present in the EU territory? If not, it cannot be a protected zone quarantine organism Is the pest present in the EU territory? If not, it cannot be a regulated non-quarantine pest. (A regulated nonquarantine pest must be present in the risk assessment area) Regulatory status (Section 3.3) If the pest is present in the EU but not widely distributed in the risk assessment area, it should be under official control or expected to be under official control in the near future The protected zone system aligns with the pest free area system under the International Plant Protection Convention (IPPC) The pest satisfies the IPPC definition of a quarantine pest that is not present in the risk assessment area (i.e. protected zone) Is the pest regulated as a quarantine pest? If currently regulated as a quarantine pest, are there grounds to consider its status could be revoked?
The Panel will not indicate in its conclusions of the pest categorisation whether to continue the risk assessment process, but following the agreed two-step approach, will continue only if requested by the risk managers. However, during the categorisation process, experts may identify key elements and knowledge gaps that could contribute significant uncertainty to a future assessment of risk. It would be useful to identify and highlight such gaps so that potential future requests can specifically target the major elements of uncertainty, perhaps suggesting specific scenarios to examine.

3.
Pest categorisation 3. Are there measures available to prevent the entry into, establishment within or spread of the pest within the EU such that the risk becomes mitigated?
Are there measures available to prevent the entry into, establishment within or spread of the pest within the protected zone areas such that the risk becomes mitigated? Is it possible to eradicate the pest in a restricted area within 24 months (or a period longer than 24 months where the biology of the organism so justifies) after the presence of the pest was confirmed in the protected zone?
Are there measures available to prevent pest presence on plants for planting such that the risk becomes mitigated?

Conclusion of pest categorisation (Section 4)
A statement as to whether (1) all criteria assessed by EFSA above for consideration as a potential quarantine pest were met and (2) if not, which one(s) were not met A statement as to whether (1) all criteria assessed by EFSA above for consideration as potential protected zone quarantine pest were met, and (2) if not, which one(s) were not met A statement as to whether (1) all criteria assessed by EFSA above for consideration as a potential regulated nonquarantine pest were met, and (2) if not, which one(s) were not met Dendrolimus sibiricus Tschetverikov is an insect of the family Lasiocampidae, subfamily Lasiocampinae.
Nuclear internal transcribed spacer 2 (ITS2) and mitochondrial COI phylogenies show that D. sibiricus and D. superans are the closest neighbours in the genus and share a common ancestor (Kononov et al., 2016). The same authors suggest the possibility of cross-hybridisation between D. sibiricus and D. pini. The species are sympatric in a part of their range and respond to the same synthetic sex pheromones (Baranchikov et al., 2006). D. sibiricus and D. pini have a very similar external morphology, but can easily be differentiated based on the structure of male genitalia (Baranchikov et al., 2006). In 2008, a new species, D. kilmez, was described from the Kirov Oblast, Western Russia (Mikkola and St ahls, 2008). However, according to nuclear (ITS2) and mitochondrial (COI, COII) markers, D. kilmez forms one single cluster with D. pini, which led to the conclusion that D. kilmez is in fact D. pini (Kononov et al., 2016).
Adults lay eggs (about 3 mm in diameter) from the middle of June to the beginning of July. One female may lay 150-400 eggs (usually 200-300) attaching them by bunches (from 3-10 up to 100 eggs) to host plant needles and twigs. Bigger females lay significantly more eggs than small ones (Boldaruev, 1955;Rozhkov, 1963;Kirichenko and Baranchikov, 2004b). Egg development takes 13-22 days. Larvae have five to six instars (exceptionally seven). Neonate larvae are about 3-4 mm in length. Body length of mature larvae may reach 100 mm (but usually varies from 50 to 60 mm). Larvae of young and middle instars (I-IV) have better growth, development and survival in groups, whereas older larvae (V-VI instars) prefer staying individually and therefore they effectively spread in the tree crowns (Kirichenko and Baranchikov, 2004a,b).
A light/dark (LD) 12:12 h photoperiod initiates larval diapause (Geispitz, 1957) and diapausing larvae overwinter once or twice depending on the length of their life cycle (Boldaruev, 1955;Rozhkov, 1963). In the first year, larvae develop to the second, third or fourth instar before coiling up in the litter and overwintering. They appear in early spring of the following year (late April-early May), feed extensively and complete their development in June, except those which overwinter a second time (Rozhkov, 1963). During this period, they cause the most significant damage since mature larvae (the two last instars) consume nearly 90% of all biomass eaten during the whole larval stage (Kirichenko, 2002;Baranchikov et al., 2002a,b).
Larvae that overwinter their first winter in the second-third instars are usually not able to complete development in the spring of the following year, so that in summer they enter summer diapause (characterised by slow movement and development in the tree crowns) and overwinter in the forest floor in the fourth or fifth instar to complete their development and pupate in the third year (Baranchikov and Kirichenko, 2002a, b). Such a complex life cycle requires 5-11 months of active larvae development.
Fifth and sixth instar larvae have urticating setae (on II and III body segments, dorsal side) that seems to serve for protection against predators and that may cause allergic reactions in humans (Rozhkov, 1963). Pupation takes place on twigs and branches of host plants in a thick silk cocoon covered by urticating setae. The larvae spend about 4 days for spinning their cocoon (Rozhkov, 1963). The pupal stage takes from 10 to 21 days (Rozhkov, 1963;Kirichenko, 2002). Adults do not feed and live 5-18 days (usually 7-10 days) (Prozorov, 1952;Rozhkov, 1963). Females are usually bigger than males (wingspan 40-80 mm). In field experiments, it was shown that adults may fly up to 15 km (Pet'ko, 2004). Distribution of individuals up to 50 km was observed (Boldaruev, 1969). Rozhkov (1963) proposed a mathematical model taking into account wing power capacity and moth weight, and estimated that females may disperse over up to 120 km and males up to 280 km, which however needs to be proven by field observations.

Intraspecific diversity
Several races have been described in the literature related to D. superans sibiricus (presently D. sibiricus): D. sibiricus sibiricus, D. s. mandshuricus, D. s. uralensis (Florov, 1938(Florov, , 1948, larch, fir and ussuri races (Rozhkov, 1963), larch, fir and five-needle pine races (Boldaruev, 1955;Ilyinskiy, 1965), based mainly on their biology (life cycle duration and host plant 'specialisation') and in some cases on adult morphology (wing colour patterns and minor variability in male genitalia). No differences were found in the responses of the larch, fir and five-needle pine races to the synthetic sex pheromones used to monitor D. sibiricus (Baranchikov et al., 2002a,b). These authors also found that these three races had the same host plant preferences.

Detection and identification of the pest
Synthetic sex attractants were identified (Klun et al., 2000;Pletnev et al., 2000) and pheromone traps were designed and tested (Baranchikov et al., 2004a,b;Pet'ko, 2004;Pet'ko et al., 2004Pet'ko et al., , 2016. They can be used from June to July, when adults emerge. This method is sensitive and may allow detection even at low population density (Pet'ko, 2004;Pet'ko et al., 2004). However, D. pini has also been observed to respond to these attractants Baranchikov et al., 2006;Petko et al., 2016).
Sampling of larvae can be done but at low population densities the probability to find larvae is extremely reduced (Pet'ko, 2004). Mature larvae can be found by beating the main trunk of potential host plants in late April-early June (Ilyinskiy, 1965). Alternatively, larvae can also be searched in late September-October in the litter under damaged trees, where they overwinter (Rozhkov, 1963).
Adults can be identified to species level using the detailed taxonomic keys developed by Rozhkov (1963). Both adults and larvae can be identified through DNA barcoding (the nucleotide sequences of the COI mitochondrial gene), or ITS2 spacer, of nuclear ribosomal gene sequence, by comparison with reference specimens of D. sibiricus originating from Russia (Mikkola and St ahls, 2008;Kononov et al., 2016) and deposited in Genbank (NCBI, 2018).

Are detection and identification methods available for the pest?
Yes, several methods exist for detection and monitoring of D. sibiricus, which could be potentially used for field surveys.

Legislation addressing the hosts of Dendrolimus sibiricus
Dendrolimus sibiricus is an Annex IAI pest, which implies that it is regulated for all plant genera and commodities. Table 4 shows the relevant regulation related to its hosts.  Kononov et al., 2016) Is the pest present in the EU territory? If present, is the pest widely distributed within the EU?
No, D. sibiricus is not reported from the EU territory.  Official statement that the wood has undergone an appropriate: (a) heat treatment to achieve a minimum temperature of 56°C for a minimum duration of 30 continuous minutes throughout the entire profile of the wood (including at its core). There shall be evidence thereof by a mark 'HT' put on the wood or on any wrapping in accordance with current usage, and on the certificates referred to in Article 13.1.(ii), or (b) fumigation to a specification approved in accordance with the procedure laid down in Article 18.2. There shall be evidence thereof by indicating on the certificates referred to in Article 13.1.(ii), the active ingredient, the minimum wood temperature, the rate (g/m 3) and the exposure time (h), or (c) chemical pressure impregnation with a product approved in accordance with the procedure laid down in Article 18.2. There shall be evidence thereof by indicating on the certificates referred to in Article 13.1.(ii), the active ingredient, the pressure (psi or kPa) and the concentration (%), and official statement that subsequent to its treatment the wood was transported until leaving the country issuing that statement outside of the flight season of the vector Monochamus, taking into account a safety margin of four additional weeks at the beginning and at the end of the expected flight season, or, except in the case of wood free from any bark, with a protective covering ensuring that infestation with Bursaphelenchus xylophilus (Steiner et B€ uhrer) Nickle et al. or its vector cannot occur.

1.5.
Whether or not listed among the CN codes in Annex V, Part B, wood of conifers (Coniferales), other than in the form of: chips, particles, sawdust, shavings, wood waste and scrap obtained in whole or part from these conifers, wood packaging material, in the form of packing cases, boxes, crates, drums and similar packings, pallets, box pallets and other load boards, pallet collars, dunnage, whether actually in use or not in the transport of objects of all kinds, except dunnage supporting consignments of wood, which is constructed from wood of the same type and quality as the wood in the consignment and which meets the same Union phytosanitary requirements as the wood in the consignment, but including that which has not kept its natural round surface, originating in Russia, Kazakhstan and Turkey.
Official statement that the wood: (a) originates in areas known to be free from: -Monochamus spp. (non-European) -Pissodes spp. (non-European) -Scolytidae spp. (non-European) The area shall be mentioned on the certificates referred to in Article 13.1.(ii), under the rubric 'place of origin,' or [. . .] or (c) has undergone kiln-drying to below 20% moisture content, expressed as a percentage of dry matter, achieved through an appropriate time/temperature schedule. There shall be evidence thereof by a mark 'kiln-dried' or 'K.D'. or another internationally recognised mark, put on the wood or on any wrapping in accordance with the current usage, or (d) has undergone an appropriate heat treatment to achieve a minimum temperature of 56°C for a minimum duration of 30 continuous minutes throughout the entire profile of the wood (including at its core). There shall be evidence thereof by a mark 'HT' put on the wood or on any wrapping in accordance with current usage, and on the certificates referred to in Article 13.1.(ii), or (e) has undergone an appropriate fumigation to a specification approved in accordance with the procedure laid down in Article 18.2. There shall be evidence thereof by indicating on the certificates referred to in Article 13.1.(ii), the active ingredient, the minimum wood temperature, the rate (g/m 3) and the exposure time (h), or (f) has undergone an appropriate chemical pressure impregnation with a product approved in accordance with the procedure laid down in Article 18.2. There shall be evidence thereof by indicating on the certificates referred to in Article 13.1.(ii), the active ingredient, the pressure (psi or kPa) and the concentration (%). 1.7 Whether or not listed among the CN codes listed in Annex V, Part B, wood in the form of chips, particles, sawdust, shavings, wood waste and scrap obtained in whole or in part from conifers (Coniferales), originating in -Russia, Kazakhstan and Turkey, non-European countries other than Canada, China, Japan, the Republic of Korea, Official statement that the wood: (a) originates in areas known to be free from: or (b) has been produced from debarked round wood, or (c) has undergone kiln-drying to below 20% moisture content, expressed as a percentage of dry matter, achieved through an appropriate time/temperature schedule, or (d) has undergone an appropriate fumigation to a specification approved in accordance with the procedure laid down in Article 18.2. There shall be evidence of the fumigation by indicating on the certificates referred to in Article 13.1.(ii), the active ingredient, the minimum wood temperature, the rate (g/m 3) and the exposure time (h), or (e) has undergone an appropriate heat treatment to achieve a minimum temperature of 56°C for a minimum duration of 30 continuous minutes throughout the entire profile of the wood (including at its core), the latter to be indicated on the certificates referred to in Article 13.1.(ii).

Isolated bark of conifers (Coniferales), originating in non-European countries
Official statement that the isolated bark: (a) has been subjected to an appropriate fumigation with a fumigant approved in accordance with the procedure laid down in Article 18.2. There shall be evidence thereof by indicating on the certificates referred to in Article 13.1.(ii), the active ingredient, the minimum bark temperature, the rate (g/m 3) and the exposure time (h), or (b) has undergone an appropriate heat treatment to achieve a minimum temperature of 56°C for a minimum duration of 30 continuous minutes throughout the entire profile of the bark (including at its core), the latter to be indicated on the certificates referred to in Article 13.1.(ii), and official statement that subsequent to its treatment the bark was transported until leaving the country issuing that statement outside of the flight season of the vector Monochamus, taking into account a safety margin of four additional weeks at the beginning and at the end of the expected flight season, or with a protective covering ensuring that infestation with Bursaphelenchus xylophilus (

3.4.
Entry, establishment and spread in the EU

Host range
The insect is capable to develop on plant species from the family Pinaceae (Rozhkov, 1963). In its native range, north-east Asia, it develops on larch (Larix spp.), fir (Abies spp.), spruce (Picea spp.) and pine (Pinus spp.), and it shows clear preferences for particular species (Vshivkova, 1976(Vshivkova, , 2004Kirichenko, 2002;Kirichenko andBaranchikov, 2004a,b, 2007) (Table 5). Siberian larch (Larix sibirica) is the most favourable host plant for the pest, followed by the five-needle Siberian pine (Pinus sibirica) and the Siberian fir (Abies sibirica). The most severe outbreaks in Siberia occur in the stands predominantly occupied by these species (Rozhkov, 1963;Boldaruev, 1955;. Development on larch provides the highest survival rate (up to 75%) in neonate larvae (most sensitive to food quality) and results in the heaviest females, with high fecundity (up to 400 eggs per female) (Kirichenko and Baranchikov, 2004a,b). Other larches (Larix kurilensis, L. gmelinii, L. cajanderi), firs (Abies sachalinensis, A. nephrolepis) and five-needle pines (Pinus pumila, P. koraiensis) some of which are distributed in northern Siberia, in the Russian Far East, Mongolia, China, Korea serve as appropriate food sources for the pest as well (Rozhkov, 1963;Ilyinskiy, 1965;Kondakov, 1974). D. sibiricus may also attack Siberian spruce (Picea obovata) in Siberia and P. ajanensis in the Russian Far East (Rozhkov, 1963;Ilyinskiy, 1965). On spruces, it performs worse comparing to the favourable hosts; on P. obovata, its fecundity hardly reaches 150 eggs per female (Kirichenko, 2002;Kirichenko and Baranchikov, 2004a,b). The two-needle Scots pine (Pinus sylvestris), widely distributed in Siberia and the Russian Far East, is a poor diet for D. sibiricus (Kirichenko, 2002). The insect may switch to two-needle pine when there is a lack of favourable hosts, i.e. during outbreaks when all favourable hosts are entirely defoliated (Kirichenko, 2002). Development on P. sylvestris causes extremely high mortality in neonate larvae (up to 93%) and may drive the pest population to collapse (Kirichenko andBaranchikov, 2004a,b, 2007). However, as an exception, a localised outbreak has been recorded on Scots pine in Siberia in the Irkutsk region in the 1990s (Epova, 1999).
Outside its native range, in Europe, the pest has a high potential to damage native and exotic coniferous species which are widely distributed and have considerable commercial value. As in its native range, the list of its potential host plants in Europe is limited to the Pinaceae family (Kirichenko et al., 2008a) (Table 5). The attempts of larvae to feed on conifers of the related families Taxaceae and Cupressaceae were unsuccessful, with 100% mortality in neonates (Kirichenko et al., 2008a). Among the Pinaceae, the European larch (Larix decidua), the North American Douglas fir (Pseudotsuga menziesii) and Weymouth pine (Pinus strobus) are highly suitable for pest development (Kirichenko et al., 2008a(Kirichenko et al., ,b, 2009(Kirichenko et al., , 2011. Feeding on these hosts results in high survival (up to 94%), larval development rates and adult fecundity (up to 340 eggs per female) (Kirichenko et al., 2008a(Kirichenko et al., , 2009(Kirichenko et al., , 2011. The Mediterranean Atlas cedar (Cedrus atlantica), the European firs Abies alba and A. nordmanniana, the North American fir (A. grandis), the Norway spruce (Picea abies) and the North American Sitka spruce (P. sitchensis) can also support the pest's development, with some variation in survival rate and larval lifespan (Kirichenko et al., 2008a(Kirichenko et al., , 2009(Kirichenko et al., , 2011. The two-needle pines distributed in Europe (Pinus sylvestris and P. nigra) and the eastern hemlock (Tsuga canadensis) introduced into Europe from North America are poor hosts, P. nigra being the poorest with up to 70% of the larvae dying in the neonate stage (Kirichenko et al., 2008a). • Isolated bark of conifers (Abies spp., Larix spp., Picea spp., Pinus spp., Tsuga spp., Pseudotsuga menziesii) from countries where the pest occurs (import requirements specified in Annex IV-A-1 7.3.); • Non-squared wood of conifers (Abies spp., Larix spp., Picea spp., Pinus spp., Tsuga spp., Pseudotsuga menziesii) from countries where the pest occurs (import requirements specified in Annex IV-A 1.5.); • Direct flight. The pest is able to fly tens of kilometres.
There is trade of coniferous wood products into the EU from some countries where D. sibiricus is present (Russia and China). Russia is a significant exporter of wood into the EU (exporting 0.7-1.2 million tonnes of wood products into the EU in 2012-2016, according to EUROSTAT).
There are no records of interception of D. sibiricus in the Europhyt database. There are 115 notifications (all MSs, 2013(all MSs, -2017 for Larix wood or bark from Russia. All notifications are related to issues concerning the phytosanitary certificate (missing, incorrect, etc.).

EU distribution of main host plants
Host species of D. sibiricus (see Section 3.4.1) are distributed throughout the EU territory ( Figure 3). However, in some parts of the EU, only low quality hosts are available. For example, in the

Climatic conditions affecting establishment
The known distribution area of the pest corresponds to several K € oppen-Geiger climatic areas (Dfc; Dfb; etc.), which are also present in some parts of the EU territory ( Figure 4) and are characterised by very cold winters and hot and dry summers. It is possible, although not scientifically established so far, that diapausing larvae of D. sibiricus have a limited capacity to overwinter in the litter outside of these areas, because they need to be protected by winter snow coverage.   Rozhkov (1963). They conclude that the pest would find suitable climatic conditions in a large part of northern and central Europe. However, Baranchikov et al. (2010), based on an unspecified bioclimatic model, concluded that the milder winter conditions in Europe would be largely unsuitable for the survival of the larvae usually overwintering in the ground under snow cover. A recent Norwegian PRA on D. sibiricus (VKM et al., 2018) discussed these different approaches and concluded that Climex would not provide suitable support for modelling organisms that overwinter in the ground. Based on the distribution of very dry and hot summers and very cold winters, the Norwegian PRA concluded that most of Norway would be climatically unsuitable for the establishment of the pest.

Spread
D. sibiricus has been observed to spread westward from its native range during the last century, reaching the Republic of Udmurtiya by the 1950s (Okunev, 1955;Talman, 1957;Rozhkov, 1963). At the beginning of the 21th century, many males were caught in pheromone traps with the Siberian moth sex pheromones in the Republic of Mariy El (500 km east of Moscow, ca 51°E) (Gninenko and Orlinskii, 2002; see also Figure 2, after Kononov et al., 2016). The capture of two individuals with the same attractant in the neighbourhood of Moscow was even reported (Gninenko and Orlinskii, 2002;Lebedeva et al., 2005). However, the accuracy of the taxonomic identification of the adults trapped in Mariy El and around Moscow has been questioned (Baranchikov et al., 2006). Trapped with the D. sibiricus sex attractant, these individuals were automatically identified as D. sibiricus, without careful study of adult morphology, whereas it is known that the related species D. pini, widely distributed in the European part of Russia, is also attracted to the synthetic sex pheromone of D. sibiricus (Baranchikov et al., 2006;Petko et al., 2016). The two species are not reliably distinguishable based on their external morphology and only the diagnostics of their male genitalia may confirm species identity (Petko et al., 2016). Thus, spreading westward of the pest itself remains uncertain (Mikkola and St ahls, 2008).
Adults can disperse from 15 up to 50 km (Pet'ko, 2004;Buldaruev, 1960). The larvae do not balloon. Large outbreaks over 800,000 ha, attributed to drought and a local increase in the sum of daily temperature above 10°C, have been recently observed in the Yenisei range half a degree northward of the established range of D. sibiricus in Siberia . It is unclear, however, whether the outbreaks developed from already existing endemic populations, or were caused by insect movements northward.
Should the pest be established in the EU, production of plants for planting in pest free places of production or pest free areas of production could reduce the risks of D. sibiricus further spreading via this pathway.
3.6.1.1. Biological or technical factors limiting the feasibility and effectiveness of measures to prevent the entry, establishment and spread of the pest • The pest is able to fly long distances, up to 50 km and possibly much more; • Small populations are difficult to detect; • D. pini is also attracted to traps baited with the D. sibiricus pheromones and can be distinguished from D. sibiricus only by the morphology of the male genitalia and DNA barcoding.

Pest control methods
• Destruction of infested material by burning or chipping/mulching (Poulsom, 2016); • Adhesive tape on individual trees, to collect larvae descending to overwinter (Poulsom, 2016); • Aerial chemical or bacterial treatments, when regulations permit; • Natural enemies: a whole list to be found in CABI (2018).

Uncertainty
Dendrolimus pini can be confused with D. sibiricus if only the external morphology is taken into account. The species can be separated, though, based on the male genitalia and molecular methods.
The historical movements westward of the pest are controversial. Mikkola and St ahls (2008) and Baranchikov et al. (2006) state that it is very slow or non-existent. The pheromone trap catches near Moscow (Gninenko and Orlinskii, 2002;Lebedeva et al., 2005) have been questioned by Baranchikov et al. (2006).
The diverging views expressed by the climatic analyses regarding the capacity of the pest to establish in parts of the EU territory request further study, in particular related to the need of a permanent winter snow coverage for the larvae overwintering in the ground.

Conclusions
D. sibiricus meets all the criteria assessed by EFSA for consideration as a quarantine pest for the EU territory. The species is presently absent from the EU, and thus, the criteria for consideration as a potential regulated non-quarantine pest are not met (Table 6).