Dataset Information

Pest risk assessment of Radopholus similis for the EU territory.

ABSTRACT: The Panel on Plant Health performed a pest risk assessment on Radopholus similis, the burrowing nematode for the EU. The quantitative assessment focused on entry, establishment, spread and impact on tropical and subtropical ornamental host plants, the main pathways for entry of R. similis into the EU. Infested consignments are expected to enter the risk assessment area on ornamentals under all scenarios. For citrus, which is a closed pathway for entry, outdoor establishment was assessed. Establishment may only take place after successful transfer from ornamental plants to citrus production systems. This event is called 'shift' in this assessment, to indicate that this is an unusual transfer. It has been estimated that establishment of this nematode in the open field in the EU citrus production areas under current temperatures is possible in most parts of the citrus production area in the EU. Temperature conditions will prevent the nematode from establishing only in the northernmost citrus areas and at higher altitudes in the south. Host plants for planting originating from infested places of production (greenhouses) within the risk assessment area are considered the main pathway for spread within the risk assessment area. Under current climatic conditions, the population of R. similis is not expected to reach damaging population levels in the open field. In case of increased temperatures due to global warming, the nematode population may reach damaging levels in very few places outdoors. Currently, main impact is considered for ornamental greenhouse production in the risk assessment area. Impact will be either caused by direct plant growth reductions or loss due to phytosanitary measures applied on regulated plants. Despite the fact that R. similis is globally considered as one of the most destructive plant parasitic nematodes, the impact in the risk assessment area is considered low.

SUBMITTER: EFSA Panel on Plant Health (PLH)

PROVIDER: S-EPMC7009971 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:As requested by the European Commission, the EFSA Panel on Plant Health (PLH) Panel assessed the risk of Diaporthe vaccinii in the EU, focusing on entry, establishment, spread and impacts on cultivated and wild Vaccinium species, the principal hosts being American and European cranberry and blueberry. Several outbreaks occurred in the EU since 1956, but most were eradicated except in Latvia. The Panel considered entry via fruits and plants for planting. The risk of establishment from discarded infected berries is much lower than from infected plants for planting, of which, potted plants and cuttings pose the greatest risk, while plug plants, derived from tissue culture and grown in pest free structures, pose a low risk. Nine per cent of the EU is highly suitable for establishment of the pathogen, mostly in the SE and NE. Following establishment, the pathogen could spread naturally over short range, and by human assistance over long range. Calculations with an integrated model for entry, establishment and spread, indicate that with current regulations, over a period of 5 years, a few hundred cultivated Vaccinium plants and several thousand Vaccinium plants in natural ecosystems would contract the disease. The associated loss of commercial production is small, less than one tonne of berries per year. On natural vegetation, the median impact after 5 years was estimated to be negligible affecting a negligible proportion of the natural Vaccinium population (2 × 10-8). However, the uncertainty of this estimate was high, due to uncertainty about the rate of spread; in a worst-case scenario (99th percentile), almost 1% of plants in natural areas would become infected. Complete deregulation (scenario A1) was predicted to increase the impact substantially, especially in natural areas, while additional measures (scenario A2) would effectively eliminate the entry of infected plants for planting, further reducing the impacts below the current situation.

Project description: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.

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Project description:Radopholus similis is a destructive, migratory, and endophytoparasitic nematode. It has two morphologically indistinguishable pathotypes (or physiological races): banana and citrus pathotypes. At present, the only reliable method to differentiate the two pathotypes is testing the infestation and parasitism of nematodes on Citrus spp. via inoculation. However, differences in inoculation methods and conditions adopted by different researchers complicate obtaining consistent results. In this study, the parasitism and pathogenicity of 10 R. similis populations on rough lemon (Citrus limon) seedlings and the tropism and invasion of rough lemon roots were tested. It revealed that populations SWK, GJ, FZ, GZ, DBSR, and YJ were citrus pathotypes, which showed parasitism and pathogenicity on rough lemon and could invade rough lemon roots, whereas populations XIN, ML, HN6, and HL were banana pathotypes, having no parasitism and pathogenicity on rough lemon and they did not invade the rough lemon roots. Four pectate lyase genes (Rs-pel-2, Rs-pel-3, Rs-pel-4, and Rs-pel-5) belonging to the Class III family from these populations were amplified and analysed. The gene Rs-pel-3 could be amplified from six citrus pathotype populations and was stably expressed in the four developmental stages of the nematode, whereas it could not be amplified from the four banana pathotypes. Rs-pel-3 expression may be related to the parasitism and pathogenicity of R. similis on rough lemon. Hence, it can be used as a molecular marker to distinguish between banana and citrus pathotypes and as a target gene for the molecular identification of these two pathotypes. KEY POINTS: • Four pectate lyase genes (Rs-pels) from Radopholus similis were cloned and analysed. • The expression of Rs-pels is different in two pathotypes of Radopholus similis. • A molecular identification method for two pathotypes of Radopholus similis using pectate lyase gene Rs-pel-3 as the target gene was established.

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Pest risk assessment of Radopholus similis for the EU territory.

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