Molecular markers for tracking the origin and worldwide distribution of invasive strains of <i>Puccinia striiformis</i>

Investigating the origin and dispersal pathways is instrumental to mitigate threats and economic and environmental consequences of invasive crop pathogens. In the case of Puccinia striiformis causing yellow rust on wheat, a number of economically important invasions have been reported, e.g., the spreading of two aggressive and high temperature adapted strains to three continents since 2000. The combination of sequence-characterized amplified region (SCAR) markers, which were developed from two specific AFLP fragments, differentiated the two invasive strains, PstS1 and PstS2 from all other P. striiformis strains investigated at a worldwide level. The application of the SCAR markers on 566 isolates showed that PstS1 was present in East Africa in the early 1980s and then detected in the Americas in 2000 and in Australia in 2002. PstS2 which evolved from PstS1 became widespread in the Middle East and Central Asia. In 2000, PstS2 was detected in Europe, where it never became prevalent. Additional SSR genotyping and virulence phenotyping revealed 10 and six variants, respectively, within PstS1 and PstS2, demonstrating the evolutionary potential of the pathogen. Overall, the results suggested East Africa as the most plausible origin of the two invasive strains. The SCAR markers developed in the present study provide a rapid, inexpensive, and efficient tool to track the distribution of P. striiformis invasive strains, PstS1 and PstS2

Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

EFSA was asked to update the 2015 EFSA risk assessment on Xylella fastidiosa for the territory of the EU. In particular, EFSA was asked to focus on potential establishment, short‐ and long‐range spread, the length of the asymptomatic period, the impact of X. fastidiosa and an update on risk reduction options. EFSA was asked to take into account the different subspecies and Sequence Types of X. fastidiosa. This was attempted throughout the scientific opinion but several issues with data availability meant that this could only be partially achieved. Models for risk of establishment showed most of the EU territory may be potentially suitable for X. fastidiosa although southern EU is most at risk. Differences in estimated areas of potential establishment were evident among X. fastidiosa subspecies, particularly X. fastidiosa subsp. multiplex which demonstrated areas of potential establishment further north in the EU. The model of establishment could be used to develop targeted surveys by Member States. The asymptomatic period of X. fastidiosa varied significantly for different host and pathogen subspecies combinations, for example from a median of approximately 1 month in ornamental plants and up to 10 months in olive, for pauca. This variable and long asymptomatic period is a considerable limitation to successful detection and control, particularly where surveillance is based on visual inspection. Modelling suggested that local eradication (e.g. within orchards) is possible, providing sampling intensity is sufficient for early detection and effective control measures are implemented swiftly (e.g. within 30 days). Modelling of long‐range spread (e.g. regional scale) demonstrated the important role of long‐range dispersal and the need to better understand this. Reducing buffer zone width in both containment and eradication scenarios increased the area infected. Intensive surveillance for early detection, and consequent plant removal, of new outbreaks is crucial for both successful eradication and containment at the regional scale, in addition to effective vector control. The assessment of impacts indicated that almond and Citrus spp. were at lower impact on yield compared to olive. Although the lowest impact was estimated for grapevine, and the highest for olive, this was based on several assumptions including that the assessment considered only Philaenus spumarius as a vector. If other xylem‐feeding insects act as vectors the impact could be different. Since the Scientific Opinion published in 2015, there are still no risk reduction options that can remove the bacterium from the plant in open field conditions. Short‐ and long‐range spread modelling showed that an early detection and rapid application of phytosanitary measures, consisting among others of plant removal and vector control, are essential to prevent further spread of the pathogen to new areas. Further data collection will allow a reduction in uncertainty and facilitate more tailored and effective control given the intraspecific diversity of X. fastidiosa and wide host range.Additional co-authors: EFSA Panel on Plant Health (PLH), Wopke van der Werf, Antonio Vicent Civera, Jonathan Yuen, Lucia Zappalà, Donato Boscia, Gianni Gilioli, Rodrigo Krugner, Alexander Mastin, Anna Simonetto, Joao Roberto Spotti Lopes, Steven White, José Cortinas Abrahantes, Alice Delbianco, Andrea Maiorano, Olaf Mosbach‐Schulz, Giuseppe Stancanelli, Michela Guzzo, Stephen Parnel

Pest categorisation of Sternochetus mangiferae

The European Commission requested EFSA to conduct a pest categorisation of Sternochetus mangiferae (Coleoptera: Curculionidae), a monophagous pest weevil whose larvae exclusively feed on mango seeds, whereas adults feed on mango foliage. S. mangiferae is a species with reliable methods available for identification. It is regulated in the EU by Council Directive 2000/29/EC where it is listed in Annex IIB as a harmful organism whose introduction into EU Protected Zones (PZ) (Alentejo, Algarve and Madeira in Portugal, and Granada and Malaga in Spain) is banned. S. mangiferae is native to South East Asia and has spread to other mango-growing areas in Africa, South America and Oceania, causing significant damage. Larvae of S. mangiferae have been detected several times in mango fruit imported into the EU. In 2013, an outbreak was declared in one PZ in Spain. Official measures taken achieved eradication, which was officially declared in January 2018. The EFSA Plant Health Panel concludes that S. mangiferae could establish again and spread in the mango-growing areas of southern EU. Considering the criteria within the remit of EFSA to assess the status as a potential Union quarantine pest (QP), as a potential protected zone quarantine pest (PZQP) or as a potential regulated non-quarantine pest (RNQP), S. mangiferae meets with no uncertainties the criteria for consideration as a potential Union QP, as it is absent from the EU, potential pathways for entry exist, and its establishment would cause an economic impact. The criterion of the pest being present in the EU, which is a prerequisite for RNQP and PZ QP, is not met

Pest categorisation of Conotrachelus nenuphar

The EFSA Panel on Plant Health performed a pest categorisation of Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), for the EU. C. nenuphar is a well-defined species, recognised as a serious pest of stone and pome fruit in the USA and Canada where it also feeds on a range of other hosts including soft fruit (e.g. Ribes, Fragaria) and wild plants (e.g. Crataegus). Adults, which are not good flyers, feed on tender twigs, flower buds and leaves. Females oviposit into host fruit; if oviposition occurs in young fruit, the fruit usually falls prematurely reducing yield; oviposition in older fruit causes surface blemishes and the fruit distorts as it develops reducing marketability. Larvae develop within host fruit but exit to pupate in soil. Adults overwinter in leaf litter. C. nenuphar is not known to occur in the EU and is listed in Annex IAI of Council Directive 2000/29/EC. Fruit infested shortly before harvest and soil with leaf litter accompanying plants for planting could potentially provide a pathway into the EU. Considering the climatic similarities between North America and Europe, and that hosts occur widely within the EU, C. nenuphar has potential to establish within the EU. There could be one or two generations per year, as in North America. Impacts could be expected, e.g. in Prunus spp. and apples. Phytosanitary measures are available to reduce the likelihood of introduction of C. nenuphar. All of the criteria assessed by EFSA for consideration as a potential Union quarantine pest are met. C. nenuphar does not meet the criteria of occurring in the EU nor plants for planting being the principal means of spread. Hence it does not satisfy all of the criteria that are within the remit of EFSA to assess for it to be regarded as a Union regulated non-quarantine pest (RNQP)

Pest categorisation of Acrobasis pirivorella

The European Commission requested EFSA to conduct a pest categorisation of Acrobasis pirivorella (Lepidoptera: Pyralidae), a monophagous moth whose larvae exclusively feed on developing buds, flowers, and fruits of cultivated and wild Pyrus spp. A. pirivorella is a species with reliable methods available for identification. A. pirivorella occurs in north-east Asia only, causing significant damage in cultivated pears. It is regulated in the EU by Council Directive 2000/29/EC where it is listed in Annex IIAI. Within this regulation, plants for planting of Pyrus spp. is a closed pathway. This species has never been reported by Europhyt. Fruits and cut branches of Pyrus spp. are open pathways. Biotic and abiotic conditions are conducive for establishment and spread of A. pirivorella in the EU. Were A. pirivorella to establish, impact on pear production is expected. Considering the criteria within the remit of EFSA to assess its regulatory plant health status, A. pirivorella meets the criteria for consideration as a potential Union quarantine pest (it is absent from the EU, potential pathways exist and its establishment would cause an economic impact). Given that A. pirivorella is not known to occur in the EU, it fails to meet some of the criteria required for regulated non-quarantine pest (RNQP) status

Pest categorisation of Toumeyella parvicornis

The EFSA Panel&nbsp;on Plant Health performed a pest categorisation of Toumeyella parvicornis (Cockerell) (Hemiptera: Coccidae) for the EU territory. This species is not included in EU Commission Implementing Regulation 2019/2072. T. parvicornis is a soft-scale insect native to North America and has been introduced to the Caribbean region and the EU. It has been present in Italy since 2014 (Abruzzo, Campania, Lazio, and Apulia regions) and in France since 2021 (Provence–Alpes–Côte d'Azur region) and is under official control. It develops on Pinus spp. (Pinaceae), feeding on the needles and twigs, especially on new growth. It is sexually reproductive, has one or more generations each year (three in southern Italy), and adult females overwinter on the Pinus needles. It has a high fecundity, up to 1,014 eggs per female in Italy, with an average of 199 eggs for the summer generation and 730 for the overwintering generation. The main natural dispersal stage is the first instar, which crawls over the plant or may be dispersed further by wind and animals. The species can be transported over longer distances with plants for planting. Large populations cause yellowing, needle loss, reduction in growth and recruitment, flagging, dieback and tree mortality. It has had a significant impact to P. pinea (stone pine) in Italy and caused a catastrophic decline of P. caribbea var. bahamensis (Caribbean pine) in the Turks and Caicos Islands. Adult and immature T. parvicornis could enter the EU with Pinus plants for planting; however, the import of Pinus from third countries where the scale is found is prohibited. Host availability and climate suitability indicate that most of the EU would be suitable for establishment. Phytosanitary measures are available to inhibit further introductions and slow the spread within the EU. T. parvicornis satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest

Pest categorisation of Aleurocanthus spp

The Panel on Plant Health performed a pest categorisation of Aleurocanthus spp., a well-de fi ned insect genus of the white fl y family Aleyrodidae (Arthropoda: Hemiptera). Dif fi culties within the taxonomy of the genus give doubt about the ability to accurately identify some members to species level. Nevertheless, the genus is thought to currently include about ninety species mainly reported from tropical and subtropical areas. The genus is listed in Council Directive 2000/29/EC and is regulated on Citrus, Fortunella and Poncirus . Several Aleurocanthu s species are highly polyphagous; Aleurocanthu s spiniferus has hosts in 38 plant families; Aleurocanthu s woglumi has more than 300 hosts including Pyrus , Rosa and Vitis vinifera as well as Citrus . A. spiniferus is present in the EU in restricted areas of Italy and Greece, where it is under of fi cial control. No other Aleurocanthus spp. are known to occur in the EU. Host plants for planting, excluding seeds, and cut fl owers or branches are the main pathways for entry. Outside of the EU, the genus can be found in regions that have climate types which also occur within the EU, suggesting establishment is possible. Aleurocanthus spp. can be signi fi cant pests of crops that are also grown in the EU. Phytosanitary measures are available to reduce the likelihood of entry into the EU, e.g. sourcing host plants for planting from pest free areas. As a genus Aleurocanthus does satisfy all the criteria that are within the remit of EFSA to assess and required by risk managers to give it consideration as a Union quarantine pest. Aleurocanthus does not meet all of the criteria to allow it consideration by risk managers as a Union regulated non-quarantine pest (RNQP). Speci fi cally, Aleurocanthus is not widespread in the EU