Pest Risk Analysis (PRA) is the process of evaluation for biological and economic evidences in order to determine whether a pest should be regulated under phyto-sanitary measures. The present mini review highlights the potential potato pathogen list recorded in Nepal harmful for potato production and productivity. At global scale altogether 135 potential quarantine pests (PQP) for potato has been recorded, while in Nepal only 92 PQP were recorded. Out of those 52, 13 and 27 were fungi, bacteria and viruses respectively. Among the 92 PQP, 34, 30 and 13 were considered at high, medium and lower risk type pathogens for potato. There was no information available on other 15 PQP.

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.

A new method for pest risk assessment and the identification and evaluation of risk‐reducing options is currently under development by the European Food Safety Authority (EFSA) Plant Health Panel. The draft method has been tested on pests of concern to the European Union (EU). The method is adaptable and can focus either on all the steps and sub‐steps of the assessment process or on specific parts if necessary. It is based on assessing changes in pest population abundance as the major driver of the impact on cultivated plants and on the environment. Like other pest risk assessment systems the method asks questions about the likelihood and magnitude of factors that contribute to risk. Responses can be based on data or expert judgment. Crucially, the approach is quantitative, and it captures uncertainty through the provision by risk assessors of quantile estimates of the probability distributions for the assessed variables and parameters. The assessment is based on comparisons between different scenarios, and the method integrates risk‐reducing options where they apply to a scenario, for example current regulation against a scenario where risk‐reducing options are not applied. A strategy has been developed to communicate the results of the risk assessment in a clear, comparable and transparent way, with the aim of providing the requestor of the risk assessment with a useful answer to the question(s) posed to the EFSA Plant Health Panel. The method has been applied to four case studies, two fungi, Ceratocystis platani and Cryphonectria parasitica, the nematode Ditylenchus destructor and the Grapevine flavescence dorée phytoplasma. Selected results from these case studies illustrate the types of output that the method can deliver.

A new method for pest risk assessment and the identification and evaluation of risk‐reducing options is currently under development by the European Food Safety Authority (EFSA) Plant Health Panel. The draft method has been tested on pests of concern to the European Union (EU). The method is adaptable and can focus either on all the steps and sub‐steps of the assessment process or on specific parts if necessary. It is based on assessing changes in pest population abundance as the major driver of the impact on cultivated plants and on the environment. Like other pest risk assessment systems the method asks questions about the likelihood and magnitude of factors that contribute to risk. Responses can be based on data or expert judgment. Crucially, the approach is quantitative, and it captures uncertainty through the provision by risk assessors of quantile estimates of the probability distributions for the assessed variables and parameters. The assessment is based on comparisons between different scenarios, and the method integrates risk‐reducing options where they apply to a scenario, for example current regulation against a scenario where risk‐reducing options are not applied. A strategy has been developed to communicate the results of the risk assessment in a clear, comparable and transparent way, with the aim of providing the requestor of the risk assessment with a useful answer to the question(s) posed to the EFSA Plant Health Panel. The method has been applied to four case studies, two fungi, Ceratocystis platani and Cryphonectria parasitica, the nematode Ditylenchus destructor and the Grapevine flavescence dorée phytoplasma. Selected results from these case studies illustrate the types of output that the method can deliver.

This project addresses the problem of the absence of a comprehensive pest risk management system that combines economic and scientific analyses into a single decisionmaking framework As such the main objective of this project is to develop a comprehensive framework and modeling system, integrating the biological profile of a pest species with economic information, to evaluate potential damages from pest invasion and the impact of alternative management decisions. A key output of the project is the development of userfriendly pest risk software that will integrate the information required of pest risk assessment into a standardized tool that can be used by policy makers/operational managers. Among other things, the software offers guidance over choice of key management options, especially those that require significant private participation.

The management of soil-pests relies largely on conventional insecticides. Within the framework of the EU's PURE project, data were collected to assess the risk of soil-pest damage to grain maize in Europe in order to implement Integrated Pest Management (IPM) of soil-pests in a more practical and sustainable manner, thus optimizing the use of soil insecticides (in-furrow or as seed-dressing) at sowing. Plant density and soil-pest damage to maize seeds and/or plants during the growing season were determined in fields with no or some risk factors. Risk assessment on a sample of sixteen experimental sites (a total of 109.95 ha of maize) located in five European countries (Germany, Hungary, Italy, Slovenia and the Netherlands) from 2011 to 2014 showed a low risk of soil-pest damage to maize. In all fields, wireworms (Agriotes spp. larvae) caused 99.5%–100% of the plant damage, meaning that damage by other soil-pests was negligible. The fields studied were divided into two groups: those with no risk and those with risk factors. According to previous research, the risk factors were Agriotes brevis Candeze and Agriotes sordidus Illiger as prevalent damaging species, soil Organic Matter content over 5%, rotation including meadows and/or double crops, as well as surrounding landscape being mainly meadows, uncultivated grass and double crops, cover crops, and poor drainage. In the fields with no risk factors, wireworm plant damage (mainly holes in the collar causing central leaf wilting) never exceeded 15%, a threshold value for potential yield reduction. Furthermore, plant damage was much lower or even negligible in the vast majority of the fields (i.e. over 90% of fields had less than 5% wireworm damage to maize plants). Risk factors, such as rotation including meadows and/or double crops, led to the percentage of cultivated land with significant wireworm plant damage being even lower than predicted (8.7% instead of 14.7%) and almost 50% of that predicted for the whole sample (2.7% instead of 4.9%). In the few cases where plant damage was higher than 15%, yield was not affected when untreated strips were compared with strips treated with soil insecticides. In all trials, the soil insecticide Tefluthrin did not significantly increase the density of healthy maize plants or grain yield. In more than 99% of cases, no economic damage to maize by soil-pests was recorded. These results demonstrate that the occurrence of risk factors may increase the risk of wireworm damage to maize crops, while the probability of damage to a field with no risk factors is always very low (less than 1%). This highlights the importance of integrating risk assessment of soil-pest damage to maize into IPM strategies, which would include: i) an “area-wide” risk assessment evaluating the possible presence of risk factors, including click beetle population monitoring with pheromone traps, and ii) “complementary field monitoring” with bait traps where risk assessment has identified the presence of risk factors. In fields with no risk factors, treating maize with soil insecticides was found to be pointless. Therefore, IPM strategies in maize that include risk assessment of soil-pest damage may lead to a significant reduction in soil insecticides use and, consequently, to a reduction in environmental impact.

The management of soil-pests relies largely on conventional insecticides. Within the framework of the EU's PURE project, data were collected to assess the risk of soil-pest damage to grain maize in Europe in order to implement Integrated Pest Management (IPM) of soil-pests in a more practical and sustainable manner, thus optimizing the use of soil insecticides (in-furrow or as seed-dressing) at sowing. Plant density and soil-pest damage to maize seeds and/or plants during the growing season were determined in fields with no or some risk factors. Risk assessment on a sample of sixteen experimental sites (a total of 109.95 ha of maize) located in five European countries (Germany, Hungary, Italy, Slovenia and the Netherlands) from 2011 to 2014 showed a low risk of soil-pest damage to maize. In all fields, wireworms (Agriotes spp. larvae) caused 99.5%–100% of the plant damage, meaning that damage by other soil-pests was negligible. The fields studied were divided into two groups: those with no risk and those with risk factors. According to previous research, the risk factors were Agriotes brevis Candeze and Agriotes sordidus Illiger as prevalent damaging species, soil Organic Matter content over 5%, rotation including meadows and/or double crops, as well as surrounding landscape being mainly meadows, uncultivated grass and double crops, cover crops, and poor drainage. In the fields with no risk factors, wireworm plant damage (mainly holes in the collar causing central leaf wilting) never exceeded 15%, a threshold value for potential yield reduction. Furthermore, plant damage was much lower or even negligible in the vast majority of the fields (i.e. over 90% of fields had less than 5% wireworm damage to maize plants). Risk factors, such as rotation including meadows and/or double crops, led to the percentage of cultivated land with significant wireworm plant damage being even lower than predicted (8.7% instead of 14.7%) and almost 50% of that predicted for the whole sample (2.7% instead of 4.9%). In the few cases where plant damage was higher than 15%, yield was not affected when untreated strips were compared with strips treated with soil insecticides. In all trials, the soil insecticide Tefluthrin did not significantly increase the density of healthy maize plants or grain yield. In more than 99% of cases, no economic damage to maize by soil-pests was recorded. These results demonstrate that the occurrence of risk factors may increase the risk of wireworm damage to maize crops, while the probability of damage to a field with no risk factors is always very low (less than 1%). This highlights the importance of integrating risk assessment of soil-pest damage to maize into IPM strategies, which would include: i) an “area-wide” risk assessment evaluating the possible presence of risk factors, including click beetle population monitoring with pheromone traps, and ii) “complementary field monitoring” with bait traps where risk assessment has identified the presence of risk factors. In fields with no risk factors, treating maize with soil insecticides was found to be pointless. Therefore, IPM strategies in maize that include risk assessment of soil-pest damage may lead to a significant reduction in soil insecticides use and, consequently, to a reduction in environmental impact.

Chapter 6 | International audience

Following the 2014 EFSA’s Panel on Plant Health scientific opinion on the pest categorisation of the spider mite Eotetranychus lewisi, the European Commission requested the Panel to perform a pest risk assessment and evaluate the risk reduction options. A stochastic model was used to assess entry, establishment and spread and related uncertainties. In the EU, E. lewisi has only been reported to occur in Portugal (Madeira). Entry pathways assessed were strawberry plants for planting from the USA, poinsettia and raspberry plants for planting, and orange and lemon fruits from third countries. Entry is most likely via poinsettia. Under current EU phytosanitary requirements, there is around a one in ten chance that E. lewisi will establish outdoors over the next 10 years. Although unlikely, establishment would most likely occur in southern Europe where environmental conditions, temperature and host density, are most suitable. If E. lewisi did establish, pest spread is expected to be mainly human assisted, most likely the mite being transported long distances on plants for planting. Nevertheless, while remaining a regulated pest, spread would be slow and most likely confined to one NUTS 2 area after 10 years. Under a scenario with enhanced measures (pest free place of production) at origin, the Panel’s assessment indicate that it is extremely unlikely that E. lewisi would establish within 10 years hence spread is also extremely unlikely. The absence of trade of host plants from Madeira to other parts of the EU could explain why E. lewisi has not spread to other EU Member States. E. lewisi is reported as reducing yield and quality of peaches and poinsettia and is regarded as a growing concern for strawberry and raspberry growers in the Americas. The Panel concludes that should E. lewisi be introduced in the EU similar impacts could be expected.