Björn Niere

Pest risk assessment of Atropellis spp. for the EU territory

Abstract Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a risk assessment for Atropellis spp. in the EU focusing on the risk of entry, the host range and the potential impacts. Atropellis is a fungal pathogen of several Pinus spp. in North America. The pathogen has not been reported from Europe and is a quarantine pest regulated in Annex IIAI of Council Directive 2000/29/EC on plants (other than fruit and seeds), isolated bark and wood of Pinus. The main pathways of entry considered were Pinus plants, wood and isolated bark. Given the ban of importing Pinus plants from outside Europe into the EU and the lack of information on EU imports of isolated Pinus bark, only the wood pathway was assessed quantitatively. The conclusion of the assessment of entry for scenario A0 (current regulatory situation) is that the risk of entry of Atropellis spp. is close to zero. This conclusion is expected to apply also in the case of removing the specific Atropellis regulations, because of the remaining generic Pinus requirements, as well as in a scenario with additional risk reduction options. The uncertainty associated with this assessment is relatively limited, given that all the quartiles of the estimated distribution of the number of potential founder populations are close to zero. For the North American Pinus spp. known to be susceptible and widely planted in the EU (mainly P. contorta and P. strobus), the damage observed in North America (loss of wood quality, stem deformations, mortality in young stands, environmental consequences) is expected in the EU to a similar (or higher) degree, should the pathogen be introduced. Similar impacts are expected on the European Pinus spp. known to be host of Atropellis spp. These include widespread and locally abundant species such as P. nigra, P. sylvestris and P. pinaster. There are, however, large uncertainties associated with this impact assessment due to the unknown susceptibility of several other Pinus spp. present in Europe. There is a need for research on the susceptibility to Atropellis spp. of those European Pinus spp.

Pest categorisation of Scirtothrips citri

Abstract The Panel on Plant Health performed a pest categorisation of the citrus thrips, Scirtothrips citri (Moulton) (Thysanoptera: Thripidae), for the European Union (EU). This is a well‐defined and distinguishable species, occurring in North America and Asia. Its precise distribution in Asia is uncertain. S. citri is a pest of citrus and blueberries and has been cited on over 50 different host species in 33 plant families. Whether all plants reported as hosts are true hosts, allowing population development of S. citri, is uncertain. S. citri feeds exclusively on young actively growing foliage and fruit. It is not known to occur in the EU and is listed in Annex IIAI of 2000/29/EC as a harmful organism. The international trade of hosts, as either plants for planting or cut flowers, provide potential pathways into the EU. However, current EU legislation prohibits the import of citrus plants for planting. Furthermore, measures aimed at the import of plants for planting in a dormant stage (no young foliage or fruits present) with no soil/growing medium attached, decreases the likelihood of the pests entry via other hosts. Considering that there are regional climatic similarities where S. citri occurs in the USA with climates in the EU, and taking EU host distribution into account, S. citri has the potential to establish in the EU, especially in citrus and blueberry growing regions around the Mediterranean where quality losses in citrus and yield losses in blueberry could occur. Phytosanitary measures are available to inhibit the likelihood of introduction of S. citri from infested countries. Considering the criteria within the remit of EFSA to assess its status as a potential Union quarantine pest (QP) or as a potential regulated non‐quarantine pest (RNQP), S. citri meets with no uncertainties the criteria assessed by EFSA for consideration as a potential Union QP.

Pest categorisation of Ips typographus

Abstract The Panel on Plant Health performed a pest categorisation of the eight‐toothed spruce bark beetle, Ips typographus L. (Coleoptera: Curculionidae, Scolytinae), for the EU. I. typographus is a well‐defined and distinguishable species, recognised mainly as a pest of spruce (Picea spp.) in Eurasia. It also attacks other conifers such as Abies spp., Larix spp., Pinus spp. and Pseudotsuga menziesii. Native to Eurasia, I. typographus has spread from the native range of spruce to new areas in Eurasia where spruce has been planted, and is now widely distributed throughout the EU (22 Member states). It is a quarantine pest listed in Annex IIB of Council Directive 2000/29/EC for Ireland and United Kingdom as protected zones. Coniferous wood, bark and wood packaging material are considered as pathways for the pest, which is also able to disperse by flight over tens of kilometres. The insects normally establish on fallen trees but can also mass‐attack healthy trees, killing millions of spruces. The males produce pheromones that attract conspecifics of both sexes. Each male attracts one to four females; each female produces 2–80 offspring. The insects also inoculate pathogenic fungi to their hosts. There are one to three generations per year. The wide current geographic range of I. typographus suggests that it is able to establish anywhere in the EU where its hosts are present. Sanitary thinning or clear‐felling are the major control methods. Pheromone mass trapping is presently judged unreliable because of the large dispersal capacity of the pest. Quarantine measures are implemented to prevent entry in yet uncolonised areas. All criteria assessed by EFSA for consideration as potential protected zone quarantine pest are met. The criteria for considering I. typographus as a potential regulated non‐quarantine pest are not met since plants for planting are not a pathway.

Pest categorisation of Synchytrium endobioticum

Abstract The Panel on Plant Health performed a pest categorisation of the fungus Synchytrium endobioticum, the causal agent of potato wart disease, for the European Union (EU). The identity of the pest is well established and reliable methods exist for its detection and identification. S. endobioticum is present in most continents. The pest is listed in Annex IAII of Directive 2000/29/EC and is present with a restricted and fragmentary distribution in the EU. The major host is Solanum tuberosum (potato), but in Mexico, the pest also affects wild Solanum spp. S. endobioticum could potentially enter the EU through multiple pathways associated with soil as substrate for non‐host plants, contaminant or commodity. The presence of the pest in 16 EU Member States characterised by different climatic conditions suggests that it could establish in the rest of the EU. The disease induces the formation of warts on potato tubers, stolons and stem bases reducing plant growth and yield and making tubers unmarketable. Additional losses may occur during storage. The only available strategy to control the disease and prevent it from spreading is the application of strict phytosanitary measures and the cultivation of potato varieties resistant to the pathotype(s) present in the infested field(s). Specific phytosanitary measures exist (Council Directive 69/464/EEC) for the control of potato wart disease in the EU. The main uncertainties refer to the distribution and host range of the pest, and the importance of some pathways of entry. S. endobioticum meets all the criteria assessed by EFSA for consideration as potential Union quarantine pest. The criteria for considering S. endobioticum as a potential Union regulated non‐quarantine pest are not met since, in addition to potato seed tubers, soil (as commodity, substrate or contaminant) and ware potato tubers are major means of spread.

Updated pest categorisation of Xylella fastidiosa

Abstract Following a request from the European Commission, the EFSA Plant Health Panel updated its pest categorisation of Xylella fastidiosa, previously delivered as part of the pest risk assessment published in 2015. X. fastidiosa is a Gram‐negative bacterium, responsible for various plant diseases, including Pierces disease, phony peach disease, citrus variegated chlorosis, olive quick decline syndrome, almond leaf scorch and various other leaf scorch diseases. The pathogen is endemic in the Americas and is present in Iran. In the EU, it is reported in southern Apulia in Italy, on the island of Corsica and in the Provence‐Alpes‐Côte dAzur region in France, as well as in the Autonomous region of Madrid, the province of Alicante and the Balearic Islands in Spain. The reported status is ‘transient, under eradication’, except for the Balearic Islands, Corsica and southern of Apulia, where the status is ‘present with a restricted distribution, under containment’. The pathogen is regulated under Council Directive 2000/29/EC and through emergency measures under http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32015D0789 (as amended http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32017D2352). The pest could enter the EU via host plants for planting and via infectious insect vectors. The host range includes hundreds of host species listed in the EFSA host plant database. In the EU, host plants are widely distributed and climatic conditions are favourable for its establishment. X. fastidiosa can spread by movement of host plants for planting and infectious insect vectors. X. fastidiosa is known to cause severe direct damage to major crops including almonds, citrus, grapevines, olives, stone fruits and also forest trees, landscape and ornamental trees, with high impacts. The criteria assessed by the Panel for consideration as a potential Union quarantine pest are met (the pathogen is present in the EU, but it has a restricted distribution and is under official control). X. fastidiosa is not considered as a regulated non‐quarantine pest (RNQP) as the pathogen may spread also via insect vector transmission.

Pest categorisation of Witches' broom disease of lime (Citrus aurantifolia) phytoplasma

Abstract The EFSA Panel on Plant Health performed a pest categorisation for the Witches broom disease of lime (Citrus aurantifolia) phytoplasma for the EU territory. The pest has been reported in a few countries in the Middle East and is not known to occur in the EU. The disease is caused by a well‐defined phytoplasma strain in the ‘Candidatus Phytoplasma aurantifolia species, for which efficient molecular detection assays are available. The most important known natural host is Citrus aurantifolia, which is only grown for ornamental purposes in the EU. Sweet limes, rough lemon and trifoliate orange are also naturally infected by that phytoplasma. The latter can be transmitted by grafting also to some citrus species. Other citrus species were reported to be resistant; however, their susceptibility has been assessed only by symptom observations, and the possible presence of phytoplasmas in symptomless plants cannot be ruled out. The phytoplasma is transmitted by the leafhopper Hishimonus phycitis, which is not known to occur in the EU. There is no information on the vector status of other phloem feeding insects of citrus present in the EU. The pest is listed in Annex IIAI of Directive 2000/29/EC. The main pathways for entry, plants for planting and the vector insect, are closed by existing legislation on import of citrus plants. Nevertheless, should the pest enter, it could establish and spread. In countries where Witches broom disease of lime (WBDL) is present, it has significant impact. The main knowledge gaps concern (1) and vertical transmission of the phytoplasma to H. phycitis eggs (2) lack of information regarding susceptibility of citrus crops grown in the EU (3) status of potential insect vectors in the EU. Therefore, the WBDL phytoplasma meets the criteria assessed by EFSA for consideration as a potential Union quarantine pest.

Guidance on quantitative pest risk assessment

Abstract This Guidance describes a two‐phase approach for a fit‐for‐purpose method for the assessment of plant pest risk in the territory of the EU. Phase one consists of pest categorisation to determine whether the pest has the characteristics of a quarantine pest or those of a regulated non‐quarantine pest for the area of the EU. Phase two consists of pest risk assessment, which may be requested by the risk managers following the pest categorisation results. This Guidance provides a template for pest categorisation and describes in detail the use of modelling and expert knowledge elicitation to conduct a pest risk assessment. The Guidance provides support and a framework for assessors to provide quantitative estimates, together with associated uncertainties, regarding the entry, establishment, spread and impact of plant pests in the EU. The Guidance allows the effectiveness of risk reducing options (RROs) to be quantitatively assessed as an integral part of the assessment framework. A list of RROs is provided. A two‐tiered approach is proposed for the use of expert knowledge elicitation and modelling. Depending on data and resources available and the needs of risk managers, pest entry, establishment, spread and impact steps may be assessed directly, using weight of evidence and quantitative expert judgement (first tier), or they may be elaborated in substeps using quantitative models (second tier). An example of an application of the first tier approach is provided. Guidance is provided on how to derive models of appropriate complexity to conduct a second tier assessment. Each assessment is operationalised using Monte Carlo simulations that can compare scenarios for relevant factors, e.g. with or without RROs. This document provides guidance on how to compare scenarios to draw conclusions on the magnitude of pest risks and the effectiveness of RROs and on how to communicate assessment results.

Evaluation of a paper by Guarnaccia et al. (2017) on the first report of Phyllosticta citricarpa in Europe

Abstract The Plant Health Panel reviewed the paper by Guarnaccia et al. (2017) and compared their findings with previous predictions on the establishment of Phyllosticta citricarpa. Four species of Phyllosticta were found by Guarnaccia et al. (2017) in Europe. P. citricarpa and P. capitalensis are well‐defined species, with P. citricarpa recorded for the first time in Europe, confirming predictions by Magarey et al. (2015) and EFSA (2008, 2014, 2016) that P. citricarpa can establish in some European citrus‐growing regions. Two new species P. paracitricarpa and P. paracapitalensis were also described, with P. paracitricarpa (found only in Greece) shown to be pathogenic on sweet orange fruits. Genotyping of the P. citricarpa isolates suggests at least two independent introductions, with the population in Portugal being different from that present in Malta and Italy. P. citricarpa and P. paracitricarpa were isolated only from leaf litter in backyards. However, since P. citricarpa does not infect or colonise dead leaves, the pathogen must have infected the above living leaves in citrus trees nearby. Guarnaccia et al. (2017) considered introduction to be a consequence of P. citricarpa having long been present or of illegal movement of planting material. In the Panels view, the fruit pathway would be an equally or more likely origin. The authors did not report how surveys for citrus black spot (CBS) disease were carried out, therefore their claim that there was no CBS disease even where the pathogen was present is not supported by the results presented. From previous simulations, the locations where Guarnaccia et al. (2017) found P. citricarpa or P. paracitricarpa were conducive for P. citricarpa establishment, with number of simulated infection events by pycnidiospores comparable to sites of CBS occurrence outside Europe. Preliminary surveys by National Plant Protection Organisations (NPPOs) have not confirmed so far the findings by Guarnaccia et al. (2017) but monitoring is still ongoing.

Pest categorisation of the Gonipterus scutellatus species complex

Abstract The Panel on Plant health performed a pest categorisation of the Australian Eucalyptus snout‐beetle Gonipterus scutellatus (Coleoptera: Curculionidae), for the EU. G. scutellatus should be referred as the G. scutellatus species complex because it includes several cryptic species. A complete nomenclature of the species present in the EU is still pending. It is a quarantine pest listed in Annex IIB of Council Directive 2000/29/EC. Protected zones are in place in Greece and Portugal (Azores). In the EU, it has been found in Italy, France, Spain and Portugal. It only consumes Eucalyptus species leaves. The main pathways of spread are the trade of Eucalyptus timber, hitchhiking in various commodities, trade of apple fruit as well as of plants for planting or plant parts. Spread by flight is also possible. The climate of the EU protected zones is similar to that of the Member States (MS) where the G. scutellatus complex is established, and the pests main host plants are present. The damaged trees suffer die‐back and the development of epicormics shoots. Severe attacks may provoke massive amounts of tree death. Biological control by using the egg parasitoid wasp Anaphes nitens is the most effective control measure. Some species within the G. scutellatus complex are not yet present in the EU (including G. scutellatus sensu stricto) and might therefore be considered as potential union quarantine pests for the EU territory. At least two species within the G. scutellatus complex (most likely G. platensis and Gonipterus species no. 2) meet the criteria assessed by EFSA for consideration as potential protected zone quarantine pests for the territory of the protected zones: Greece and Portugal (Azores). The criteria for considering the G. scutellatus complex as a potential regulated non‐quarantine pest for the EU are not met since plants for planting are not the main pathway.

Pest categorisation of Anthonomus quadrigibbus

Abstract The Panel on Plant Health performed a pest categorisation of the weevil Anthonomus quadrigibbus Say, (Coleoptera: Curculionidae), for the EU. A. quadrigibbus is a well‐defined and distinguishable species, recognised as an occasional pest of apples, pears and sour cherries in North America where it also feeds on a range of wild rosaceous plants such as Crataegus and Amelanchier. Adults feed on leaves, flowers and fruit. Feeding damage to fruit reduces quality. Females oviposit into young fruit, causing surface blemishes and resulting in distortion as the fruit develops. Marketability is subsequently reduced. Larvae and pupae develop within host fruit. Most infested fruit fall prematurely, reducing yield. A. quadrigibbus was regarded as a more serious pest in the early 20th century. A. quadrigibbus is not known to occur in the EU and is listed in Annex IIAI of Council Directive 2000/29/EC under the synonym Tachypterellus quadrigibbus. Host plants for planting and infested fruit could potentially provide a pathway into the EU. Considering the climatic similarities between North America and Europe, and that wild and commercial hosts occur widely within the EU, A. quadrigibbus has the potential to establish within the EU. There would be one generation per year, as in North America. Impacts could be expected in apple, pear and perhaps sour cherry orchards. The level of impacts would be uncertain. There is also uncertainty regarding whether A. quadrigibbus would extend its host range to include other Rosaceae within the EU. Phytosanitary measures are available to reduce the likelihood of introduction of A. quadrigibbus. All criteria assessed by EFSA for consideration as a potential Union quarantine pest are met. As A. quadrigibbus is not known to occur in the EU, this criterion assessed by EFSA to consider it as a Union regulated non‐quarantine pest is not met.