Analysis of Defense-Related Gene Expression and Leaf Metabolome in Wheat During the Early Infection Stages of Blumeria graminis f. sp. tritici.

Blumeria graminis f. sp. tritici (Bgt) is an obligate biotrophic fungal pathogen responsible for powdery mildew in bread wheat (Triticum aestivum). Upon Bgt infection, the wheat plant activates basal defense mechanisms, namely PAMP-triggered immunity, in the leaves during the first few days. Understanding this early stage of quantitative resistance is crucial for developing new breeding tools and evaluating plant resistance inducers for sustainable agricultural practices. In this sense, we used a combination of transcriptomic and metabolomic approaches to analyze the early steps of the interaction between Bgt and the moderately susceptible wheat cultivar Pakito. Bgt infection resulted in an increasing expression of genes encoding pathogenesis-related (PR) proteins (PR1, PR4, PR5, and PR8) known to target the pathogen, during the first 48 h postinoculation. Moreover, RT-qPCR and metabolomic analyses pointed out the importance of the phenylpropanoid pathway in quantitative resistance against Bgt. Among metabolites linked to this pathway, hydroxycinnamic acid amides containing agmatine and putrescine as amine components accumulated from the second to the fourth day after inoculation. This suggests their involvement in quantitative resistance via cross-linking processes in cell walls for reinforcement, which is supported by the up-regulation of PAL (phenylalanine ammonia-lyase), PR15 (oxalate oxidase) and POX (peroxidase) after inoculation. Finally, pipecolic acid, which is considered a signal involved in systemic acquired resistance, accumulated after inoculation. These new insights lead to a better understanding of basal defense in wheat leaves after Bgt infection.

A Laminarin-Based Formulation Protects Wheat Against Zymoseptoria tritici via Direct Antifungal Activity and Elicitation of Host Defense-Related Genes.

The present study aimed to evaluate the potential of the laminarin-based formulation Vacciplant to protect and induce resistance in wheat against Zymoseptoria tritici, a major pathogen on this crop. Under greenhouse conditions, a single foliar spraying of the product 2 days before inoculation with Z. tritici reduced disease severity and pycnidium density by 42 and 45%, respectively. Vacciplant exhibited a direct antifungal activity on Z. tritici conidial germination both in vitro and in planta. Moreover, it reduced in planta substomatal colonization as well as pycnidium formation on treated leaves. Molecular investigations revealed that Vacciplant elicits but did not prime the expression of several wheat genes related to defense pathways, including phenylpropanoids (phenylalanine ammonia-lyase and chalcone synthase), octadecanoids (lipoxygenase and allene oxide synthase), and pathogenesis-related proteins (ß-1,3-endoglucanase and chitinase). By contrast, it did not modulate the expression of oxalate oxidase gene involved in the reactive oxygen species metabolism. Ultrahigh-performance liquid chromatography-mass spectrometry analysis indicated limited changes in leaf metabolome after product application in both noninoculated and inoculated conditions, suggesting a low metabolic cost associated with induction of plant resistance. This study provides evidence that the laminarin-based formulation confers protection to wheat against Z. tritici through direct antifungal activity and elicitation of plant defense-associated genes.

Bio-Inspired Rhamnolipids, Cyclic Lipopeptides and a Chito-Oligosaccharide Confer Protection against Wheat Powdery Mildew and Inhibit Conidia Germination.

Plant protection is mainly based on the application of synthetic pesticides to limit yield losses resulting from diseases. However, the use of more eco-friendly strategies for sustainable plant protection has become a necessity that could contribute to controlling pathogens through a direct antimicrobial effect and/or an induction of plant resistance. Three different families of natural or bioinspired compounds originated from bacterial or fungal strains have been evaluated to protect wheat against powdery mildew, caused by the biotrophic Blumeria graminis f.sp. tritici (Bgt). Thus, three bio-inspired mono-rhamnolipids (smRLs), three cyclic lipopeptides (CLPs, mycosubtilin (M), fengycin (F), surfactin (S)) applied individually and in mixtures (M + F and M + F + S), as well as a chitosan oligosaccharide (COS) BioA187 were tested against Bgt, in planta and in vitro. Only the three smRLs (Rh-Eth-C12, Rh-Est-C12 and Rh-Succ-C12), the two CLP mixtures and the BioA187 led to a partial protection of wheat against Bgt. The higher inhibitor effects on the germination of Bgt spores in vitro were observed from smRLs Rh-Eth-C12 and Rh-Succ-C12, mycosubtilin and the two CLP mixtures. Taking together, these results revealed that such molecules could constitute promising tools for a more eco-friendly agriculture.

Saccharin Provides Protection and Activates Defense Mechanisms in Wheat Against the Hemibiotrophic Pathogen Zymoseptoria tritici.

Plant resistance inducers are among the most promising alternatives to develop sustainable crop protection. Here, we examined the ability of saccharin, a metabolite derived from probenazole, to protect wheat against Zymoseptoria tritici, the most frequently occurring and damaging foliar pathogen on this crop. The experiments were performed in the greenhouse by treating seedlings of the wheat cultivar 'Alixan' with 15 mM of saccharin 2 days before challenge inoculation with the Z. tritici pathogenic strain T02596. Foliar application of saccharin resulted in 77% lower disease severity than in nontreated control plants. In vitro and in planta assays showed that saccharin did not exhibit any direct antifungal effect on spore germination or hyphal growth. Molecular investigations from 2 to 7 days posttreatment (dpt) revealed that saccharin treatment upregulates the expression of genes encoding for lipoxygenase (LOX) at all sampled time points and pathogenesis-related protein 1 (PR1) at 7 dpt, in both noninfectious and infectious contexts, as well as peroxidase (POX2) in noninfectious conditions. However, saccharin did not induce significant change in the expression of PAL gene encoding for phenylalanine ammonia-lyase. Our findings report for the first time the potential of saccharin to confer protection in wheat against Z. tritici through an elicitation and priming of LOX and PR gene-related defense pathways. Additional investigations would provide a better deciphering of defense mechanisms activated by this molecule in wheat against Z. tritici.

Importance of the C12 Carbon Chain in the Biological Activity of Rhamnolipids Conferring Protection in Wheat against Zymoseptoria tritici.

The hemibiotrophic fungus Zymoseptoria tritici, responsible for Septoria tritici blotch, is currently the most devastating foliar disease on wheat crops worldwide. Here, we explored, for the first time, the ability of rhamnolipids (RLs) to control this pathogen, using a total of 19 RLs, including a natural RL mixture produced by Pseudomonas aeruginosa and 18 bioinspired RLs synthesized using green chemistry, as well as two related compounds (lauric acid and dodecanol). These compounds were assessed for in vitro antifungal effect, in planta defence elicitation (peroxidase and catalase enzyme activities), and protection efficacy on the wheat-Z. tritici pathosystem. Interestingly, a structure-activity relationship analysis revealed that synthetic RLs with a 12 carbon fatty acid tail were the most effective for all examined biological activities. This highlights the importance of the C12 chain in the bioactivity of RLs, likely by acting on the plasma membranes of both wheat and Z. tritici cells. The efficacy of the most active compound Rh-Est-C12 was 20-fold lower in planta than in vitro; an optimization of the formulation is thus required to increase its effectiveness. No Z. tritici strain-dependent activity was scored for Rh-Est-C12 that exhibited similar antifungal activity levels towards strains differing in their resistance patterns to demethylation inhibitor fungicides, including multi-drug resistance strains. This study reports new insights into the use of bio-inspired RLs to control Z. tritici.

New salicylic acid and pyroglutamic acid conjugated derivatives confer protection to bread wheat against Zymoseptoria tritici.

BACKGROUND: To promote sustainable agriculture and healthy food, research that contributes towards a new generation of eco-friendly phytosanitary compounds is increasingly encouraged. The plant hormone salicylic acid (SA) is known for its ability to induce resistance in plants against a wide range of pathogens, whereas pyroglutamic acid (PGA), a constrained analogue of γ-aminobutyric acid, has never been studied in the context of plant protection. RESULTS: The present study investigated for the first time the protection efficacy of SA and PGA and five new conjugated derivatives against Zymoseptoria tritici, the main pathogen in wheat crops. SA and four derivatives showed significant disease severity reductions in planta (up to 49%). In vitro assays revealed that some molecules, including SA, displayed a small direct antifungal activity, whereas others, such as PGA, showed no effect. This finding suggests that, especially for molecules without any direct activity, the mode of action relies mainly on the induction of plant resistance. CONCLUSION: Further investigations are needed to identify the defence pathways involved in plant resistance mechanisms elicited or primed by the molecules. The manufacture of these products was easily achieved on a scale of tens of grams of raw materials, and is easily scalable. The synthetic pathway is simple, short and inexpensive. For all of these reasons, the production of the target molecules is attractive for producers, whereas the prospect of a generation of non-polluting compounds with lasting efficiency against Z. tritici in wheat comes at a key moment for the sustainability of agriculture. © 2018 Society of Chemical Industry.

Genetic Structure of Zymoseptoria tritici in Northern France at Region, Field, Plant, and Leaf Layer Scales.

Population genetic structure of the worldwide-distributed wheat pathogen Zymoseptoria tritici has been extensively studied at large geographical scales, but to a much less extent at small or local spatial scales. A total of 627 single-conidial fungal isolates were sampled from several locations in northern France (Hauts-de-France Region) to assess fungal genetic structure at region, field, plant, and leaf layer scales, using highly polymorphic microsatellite markers and mating type idiomorphs. Important and overall similar levels of both gene and genotype diversities (gene diversity values of ≥0.44 and haplotype frequencies of ≥94%) were found at all the examined scales. Such rates of diversity are likely due to an active sexual recombination in the investigated areas, as revealed by equal proportions of the two mating types scored in all sampled populations. Interestingly, a rare occurrence of clones among lesions from a same leaf, as well as among leaves from different plant leaf layers (e.g., upper versus lower leaves), was highlighted, indicating that ascospores contribute much more than expected to Z. tritici epidemics, compared with pycnidiospores. Population structure and analyses of molecular variance revealed significant genetic differentiation at the regional scale (GST = 0.23) and, as expected, not at the other more local scales (GST ≤ 0.01). Further analyses using Bayesian and unweighted neighbor-joining statistical methods detected six genetic clusters within the regional population, overall distributed according to the locations from which the isolates were sampled. Neither clear directional relative migration linked to the geographical distribution of the locations, nor isolation by distance, were observed. Separate evolutionary trajectories caused by selection and adaptations to habitat heterogeneity could be the main forces shaping such structuration. This study provides new insights into the epidemiology and the genetic structure of Z. tritici at small local and, for the first time, at single plant and leaf layer scales. Such findings would be helpful in implementing effective control strategies.

Exogenous trehalose induces defenses in wheat before and during a biotic stress caused by powdery mildew.

Powdery mildew would be one of the most damaging wheat diseases without the extensive use of conventional fungicides. Some of the alternative control strategies currently emerging are based on the use of resistance inducers. The disacharride trehalose (TR) is classically described as an inducer of defenses in plants to abiotic stress. In this work, the elicitor or priming effect of TR was investigated in wheat both before and during a compatible wheat-powdery mildew interaction through molecular, biochemical, and cytological approaches. In noninoculated conditions, TR elicited the expression of genes encoding chitinase (chi, chi1, and chi4 precursor), pathogenesis-related protein 1, as well as oxalate oxidase (oxo). Moreover, lipid metabolism was shown to be altered by TR spraying via the upregulation of lipoxygenase (lox) and lipid-transfer protein (ltp)-encoding gene expression. On the other hand, the protection conferred by TR to wheat against powdery mildew is associated with the induction of two specific defense markers. Indeed, in infectious conditions following TR spraying, upregulations of chi4 precursor and lox gene expression as well as an induction of the LOX activity were observed. These results are also discussed with regard to the impact of TR on the fungal infectious process, which was shown to be stopped at the appressorial germ tube stage. Our findings strongly suggest that TR is a true inducer of wheat defense and resistance, at least toward powdery mildew.

Pest categorisation of Coniella castaneicola.

The European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of Coniella castaneicola (Ellis & Everh) Sutton, following commodity risk assessments of Acer campestre, A. palmatum, A. platanoides, A. pseudoplatanus, Quercus petraea and Q. robur plants from the UK, in which C. castaneicola was identified as a pest of possible concern to the EU. When first described, Coniella castaneicola was a clearly defined fungus of the family Schizoparmaceae, but due to lack of a curated type-derived DNA sequence, current identification based only on DNA sequence is uncertain and taxa previously reported to be this fungus based on molecular identification must be confirmed. The uncertainty on the reported identification of this species translates into uncertainty on all the sections of this categorisation. The fungus has been reported on several plant species associated with leaf spots, leaf blights and fruit rots, and as an endophyte in asymptomatic plants. The species is reported from North and South America, Africa, Asia, non-EU Europe and Oceania. Coniella castaneicola is not known to occur in the EU. However, there is a key uncertainty on its presence and geographical distribution worldwide and in the EU due to its endophytic nature, the lack of systematic surveys and possible misidentifications. Coniella castaneicola is not included in Commission Implementing Regulation (EU) 2019/2072 and there are no interceptions in the EU. Plants for planting, fresh fruits and soil and other growing media associated with infected plant debris are the main pathways for its entry into the EU. Host availability and climate suitability in parts of the EU are favourable for the establishment and spread of the fungus. Based on the scarce information available, the introduction and spread of C. castaneicola in the EU is not expected to cause substantial impacts, with a key uncertainty. Phytosanitary measures are available to prevent its introduction and spread in the EU. Because of lack of documented impacts, Coniella castaneicola does not satisfy all the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest.

Pest categorisation of Popillia quadriguttata.

The EFSA Panel on Plant Health performed a pest categorisation of Popillia quadriguttata (Coleoptera: Scarabaeidae), following a commodity risk assessment of bonsai Pinus parviflora grafted onto P. thunbergii from China, in which P. quadriguttata was identified as a pest of possible concern for the territory of the European Union. This is a univoltine polyphagous pest that occurs in eastern Asia from Vietnam northwards through eastern China and Taiwan, South Korea and into Far East Russia. Hosts include species of fruit trees within the genera Malus and Prunus, trees of forestry and environmental importance such as Quercus and Ulmus, shrubs such as Wisteria, soft fruit such as Rubus, grasses, including amenity turf and field crops such as potatoes, maize and soybean. Adults feed on host leaves, tender stems, flower buds, flowers and fruits; larvae feed on host roots. In northern China P. quadriguttata is a major pest of soybean; in South Korea, P. quadriguttata is one of the most serious insect pests of golf course turf. P. quadriguttata could enter the EU on various pathways including infested soil and growing media accompanying host plants for planning. Biotic factors (host availability) and abiotic factors (climate suitability) suggest that large parts of the EU would be suitable for establishment. Local spread would be mainly via natural dispersal of adults. Long distance spread would be facilitated by the movement of eggs, larvae and pupae infesting soil especially with plants for planting; adults could spread on plants for planting without soil. Economic and or environmental impacts would be expected on a range of plants if P. quadriguttata were to establish in the EU. Phytosanitary measures are available to reduce the likelihood of its introduction. P. quadriguttata satisfies all of 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 Cenopalpus irani.

The EFSA Panel on Plant Health performed a pest categorisation of Cenopalpus irani (Trombidiformes: Tenuipalpidae), known as the Iranian false spider mite, following the commodity risk assessment of Malus domestica plants from Türkiye, in which C. irani was identified as a pest of possible concern for the territory of the European Union (EU). The pest is only known to be present in Iran and Türkiye and has not been reported from the EU. The mite primarily feeds on Rosaceae plants but is considered polyphagous. Important crops of the EU that are hosts of C. irani include apples (Malus domestica), pears (Pyrus communis) and figs (Ficus carica). Plants for planting and fruits provide potential pathways for entry into the EU. Host availability and climate suitability in southern EU countries would most probably allow this species to successfully establish and spread. This mite is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. Phytosanitary measures are available to reduce the likelihood of entry and spread of this species into the EU. The mite C. irani satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest, although there is a key uncertainty over the likelihood and magnitude of impact.

Risk assessment of Phlyctinus callosus for the EU.

Following a request from the European Commission, the EFSA Panel on Plant Health performed a quantitative risk assessment for the EU of Phlyctinus callosus (Coleoptera: Curculionidae), a polyphagous pest occurring in Australia, New Zealand and South Africa. The current risk assessment focused on potential pathways for entry, the climatic conditions allowing establishment, the expected spread capacity and the impact considering a time horizon of 10 years (2023-2032). The Panel identified the import of apples, cut flowers and table grapes as the most relevant entry pathways. Over the next 10 years, an annual median estimate of approximately 49.5 (90% certainty range, CR, ranging from 4.0 to 881.2) potential P. callosus founder populations are expected. When the probability of establishment is considered and climatic indicators are used to define the areas in the EU where establishment is possible, the model estimated a median of 1 founder population every 1.3 years (90% CR: 1 every 30.8 years to 23.3 per year) in the scenario where the areas are defined by the union of all the climatic indicators and 1 founder population every 11.9 years (90% CR: 1 every 256.6 years to 2.5 per year) in the scenario where establishment is possible only in the areas defined by the climatic indicator of minimum soil temperature. The estimated number of founder populations per year is mostly driven by the probability of establishment in the rural areas, infestation rate in table grapes and the probability of transfer to a suitable host in the rural area. The risk of entry for cut flowers and apples is substantially lower than the risk from the table grapes. If such founder populations were to establish, P. callosus is estimated to spread by natural dispersal and common agricultural practices at a rate of 15.5 m/year (90% CR 5.1-46.8 m/year) after a lag phase of 4.0 years (90% CR 1.3-8.7 years). The impact, expressed as percentage loss of the production directly attributable to P. callosus in the areas where establishment is possible and assuming farmers do not apply specific control measures was estimated at 0.5% (90% CR 0.01%-2.8%) for cut flowers/foliage, 5.2% (90% CR 2.2%-11.7%) for apples and 2% (90% CR 1.3%-5.2%) for table grapes. Options for risk reduction are discussed, but their effectiveness is not quantified.

Pest categorisation of Ceroplastes rubens.

The European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of Ceroplastes rubens Maskell (Hemiptera: Coccidae), following the commodity risk assessments of Acer palmatum plants grafted on A. davidii and Pinus parviflora bonsai plants grafted on P. thunbergii from China, in which C. rubens was identified as a pest of possible concern to the European Union (EU). The pest, which is commonly known as the pink, red or ruby wax scale, originates in Africa and is highly polyphagous attacking plants from more than 193 genera in 84 families. It has been present in Germany since 2010 in a single tropical glasshouse. It is known to attack primarily tropical and subtropical plants, but also other host plants commonly found in the EU, such as Malus sylvestris, Prunus spp., Pyrus spp. and ornamentals. It is considered an important pest of Citrus spp. The pink wax scale reproduces mainly parthenogenetically, and it has one or two generations per year. Fecundity ranges from 5 to 1178 eggs. Crawlers settle usually on young twigs and later stages are sessile. All life stages of C. rubens egest honeydew on which sooty mould grows. Host availability and climate suitability suggest that parts of the EU would be suitable for establishment. Plants for planting and cut branches provide the main pathways for entry. Crawlers could spread over short distances naturally through wind, animals, humans or machinery. C. rubens could be dispersed more rapidly and over long distances via infested plants for planting for trade. The introduction of C. rubens into the EU could lead to outbreaks causing damage to orchards, amenity ornamental trees and shrubs. Phytosanitary measures are available to inhibit the entry and spread of this species. C. rubens satisfies 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 Monema flavescens.

The EFSA Panel on Plant Health performed a pest categorisation of Monema flavescens (Lepidoptera, Limacodidae), following the commodity risk assessment of Acer palmatum plants grafted on A. davidii from China, in which M. flavescens was identified as a pest of possible concern to the European Union. This species can be identified by morphological taxonomic keys and by barcoding. The adults of the overwintering generation emerge from late June to late August. The eggs are laid in groups on the underside of the host-plant leaves, on which the larvae feed throughout their six to eight larval instars. Pupation occurs in ovoid cocoons at the junction between twigs and branches, or on the trunk. Overwintering occurs as fully grown larvae or prepupae in their cocoon. There are one or two generations per year. M. flavescens is polyphagous and feeds on broadleaves; it has been reported on 51 plant species belonging to 24 families. It mainly occurs in Asia (Bhutan, China, the Democratic People's Republic of Korea, Japan, Nepal, the Republic of Korea), Russia (Eastern Siberia) and Taiwan. It is also present in the USA (Massachusetts). The pest's flight capacities are unknown. The main pathway for entry and spread is plants for planting with cocoons attached. This is partially closed by prohibition of some hosts. In several EU member states climatic conditions are conducive for establishment and many host plants are widespread. Introduction of M. flavescens may result in defoliations influencing tree health and forest diversity. The caterpillars also have urticating spines affecting human health. Phytosanitary measures are available to reduce the likelihood of entry, establishment and spread, and there is a definite potential for classical biological control. Recognising that natural enemies prevent M. flavescens being regarded as a pest in Asia, there is uncertainty regarding the magnitude of potential impact in EU depending on the influence of natural enemies. All criteria assessed by EFSA for consideration as a potential quarantine pest are met.

Pest categorisation of Matsucoccus matsumurae.

The EFSA Panel on Plant Health performed a pest categorisation of Matsucoccus matsumurae (Hemiptera: Matsucoccidae), the Massonian pine bast scale, for the EU territory. This pest categorisation was initiated following the commodity risk assessment of artificially dwarfed plants from China consisting of Pinus parviflora (Japanese white pine) grafted on P. thunbergii (Japanese black pine) performed by EFSA, in which M. matsumurae was identified as a pest of possible concern. However, its identity is not firmly established due to uncertainty regarding its taxonomic relationship with Matsucoccus pini (Green), a species widespread in Europe. M. matsumurae occurs in western China and has been reported as a pest of P. massoniana (Chinese red pine) and P. thunbergii. These hosts occur in the EU as ornamental/amenity trees. Other scales in the Matsucoccus genus feed on a variety of Pinus species and the host range of M. matsumurae could be wider than is currently recorded. The scale has one or two generations per year. All stages occur on the branches and stems of hosts with developing nymphs and adult females feeding through the bark on host phloem vessels. Symptoms include the yellowing/browning of host needles, early needle drop, desiccation of shoots and bark necrosis. The most serious infestations occur in hosts that are 8-25 years old and there can be some host mortality. In principle, host plants for planting and plant products such as cut branches and wood with bark could provide entry pathways into the EU. However, prohibitions on the import of Pinus from non-European third countries regulate these pathways. In China, M. matsumurae occurs in regions with temperate humid conditions and hot summers. These conditions are also found in parts of southern EU. Were M. matsumurae to establish in the EU, it is conceivable that it could expand its host range; however, this remains uncertain. Some uncertainty exists over the magnitude of potential impacts. M. matsumurae satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest, assuming M. pini is not a synonym, which is a key uncertainty.

Pest categorisation of Shirahoshizo flavonotatus.

The EFSA Panel on Plant Health performed a pest categorisation of Shirahoshizo patruelis (Voss, 1937) (Coleoptera: Curculionidae), following the commodity risk assessment of bonsai plants from China consisting of Pinus parviflora grafted on P. thunbergii, in which S. patruelis was identified as a pest of possible concern to the European Union (EU). This categorisation refers to S. flavonotatus, which is the pest's current valid scientific name. It is native to China and has never been recorded in the EU. It completes from 2 to 3 generations per year. Eggs are laid in cracks and crevices of trunks and branches with bark thickness of approximately 0.6-1.2 cm. The pest overwinters as an adult or as a mature larva under the bark. Plants for planting, wood with bark and wood products provide pathways for entry. Although the weevil has been reported to carry the nematode Bursaphelenchus xylophilus, it is not considered a vector. Climatic conditions and availability of host plants in some EU countries would allow S. flavonotatus to establish and spread. Impact on Pinus spp. is anticipated. Recognising that the weevil is reported to attack both weakened and healthy trees, there is uncertainty on the magnitude of impact. Its recorded capacity to attack non-Asian Pinus species also indicates its ability to adapt and expand the range of trees it can utilise as hosts, which could include European Pinus species. Phytosanitary measures are available to reduce the likelihood of entry and spread. S. flavonotatus meets the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Pest categorisation of Calepitrimerus baileyi.

The EFSA Panel on Plant Health performed a pest categorisation of Bailey's rust mite, Calepitrimerus baileyi Keifer (Acariformes: Eriophyidae), following the commodity risk assessment of Malus domestica plants from Türkiye performed by EFSA, in which C. baileyi was identified as a pest of possible concern to the European Union. This mite is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. The eriophyid is known to occur in Africa, America, Asia, Europe (Greece and Serbia) and Oceania on Malus spp., which is the only confirmed host genus for C. baileyi. Plants for planting of Malus spp. are the main potential pathway for entry into the EU. However, plants for planting of the genus Malus Mill. are considered as high-risk plants (EU 2018/2019) and therefore prohibited from entering the EU unless granted a country-specific derogation. This is the case for the import of Malus spp. plants for planting from Serbia ((EU) 2020/1361 corrected by 2022/1309). Therefore, this derogation could provide a plausible entry pathway for C. baileyi into the EU. Climatic conditions and the ample availability of the host, Malus spp., in the EU are conducive for establishment, as proven by the occurrence of C. baileyi in Greece. However, the species is not reported as having an impact in Greece, despite reports of damage outside the EU. Measures to prevent further entry and spread of C. baileyi in the EU are available. C. baileyi satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest. However, uncertainties about the distribution of C. baileyi within the EU and its impact on apples in the EU are considered key and affect the confidence of conclusions for this categorisation.

Pest categorisation of Malacosoma parallela.

The EFSA Panel on Plant Health performed a pest categorisation of Malacosoma parallela (Staudinger) (Lepidoptera: Lasiocampidae) for the territory of the European Union, following commodity risk assessments of Berberis thunbergii, Malus domestica, Prunus persica and P. dulcis plants for planting from Türkiye, in which M. parallela came to attention as of possible concern. M. parallela is commonly known as the mountain ring silk moth and is a polyphagous leaf-eating pest in west-central Asia, primarily feeding on deciduous trees and shrubs, and known to cause serious damage to Malus, Prunus, and Quercus species. It is found at a range of altitudes from 130 m to 3000 m although most common above 1000 m. It is a univoltine species. Eggs are laid in masses on twigs and branches in the summer and larvae hatch the following spring to feed on buds and fresh leaves. Host plants can be completely defoliated. Plants for planting and cut branches provide pathways for entry, especially if infested with egg masses. Host availability and climate suitability suggest that parts of the EU would be suitable for establishment. Adults can fly and the pest could spread naturally within the EU although adults only live for a few days. Faster and more extensive spread is therefore more likely via egg masses moved on plants for planting. The introduction of M. parallela into the EU could lead to outbreaks causing damage to deciduous trees and shrubs in forests and orchards. Phytosanitary measures are available to inhibit the entry and spread of this species. M. parallela 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 Pratylenchus loosi.

Following the EFSA commodity risk assessment of Malus domestica plants imported from Türkiye into the EU, the EFSA Panel on Plant Health performed a pest categorisation of Pratylenchus loosi (Nematoda: Pratylenchidae) for the EU. Pratylenchus loosi belongs to the order Rhabditida, subfamily Pratylenchidae. This nematode is not known to be present in the EU. The species is not included in the EU Commission Implementing Regulation 2019/2072. The pest occurs primarily in tropical, subtropical and warm temperate areas. It is widely distributed in Asian countries, with tea plants (Camellia sinensis) as the main host. The pest was reported from more than 60 plant species, but reports from hosts other than C. sinensis, e.g. citrus (Citrus spp.) and banana (Musa spp.), are associated with high uncertainty due to doubtful pest identification. Morphological and molecular methods are available for the identification of the pest. Pathways of entry are host plants for planting except seeds, as well as soil attached to plants for planting, machinery or footwear. Soil import to the EU is prohibited from third countries. The climatic preferences of P. loosi are compatible with the microclimatic conditions occurring in the areas of the EU where tea is grown outside. The impact of the nematode is primarily known for Asian countries, where it is a devastating pathogen on tea plants, but there is a key uncertainty on impacts on hosts other than tea. Considering the strong pathogenicity of the pest, its establishment in tea producing areas would have negative consequences for tea producers. Therefore, the Panel concludes that P. loosi 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 Crisicoccus seruratus.

Following the commodity risk assessments of Acer palmatum plants grafted on A. davidii from China, in which Crisicoccus matsumotoi (Hemiptera: Pseudococcidae) was identified as a pest of possible concern, the European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of C. matsumotoi for the territory of the European Union. Recent taxonomic revision of the genus Crisisoccus concluded that C. matsumotoi is a synonym of C. seruratus; therefore, the categorisation will use the current valid name C. seruratus. It is an insect pest native to Japan, feeding on species in 13 plant families. There are reports of its presence also in China and the Republic of Korea, but there is great uncertainty about the identity of the species for these records. Therefore, there is uncertainty about the species referred to as C. matsumotoi in the commodity risk assessments of A. palmatum. C. seruratus is a multivoltine species. It has three generations per year and overwinters as a nymph. The most important crops that may be affected by C. seruratus are figs (Ficus carica), grapes (Vitis spp.), nashi pears (Pyrus pyrifolia var. culta), persimmons (Diospyros kaki) and walnuts (Juglans regia). Plants for planting and fruits provide potential pathways for entry into the EU. Host availability and climate suitability suggest that the central, northern and some areas of southern EU countries would be suitable for the establishment of C. seruratus. The introduction of this mealybug would likely have an economic impact in the EU through yield reduction and fruit downgrading because of honeydew deposition and the consequent growth of sooty moulds. This insect is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. Phytosanitary measures are available to reduce the likelihood of entry and spread of this species into the EU. C. seruratus satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.