The EFSA quantitative approach to pest risk assessment – methodological aspects and case studies

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.     

From CLIMEX to PESKY,a generic expert system for pest risk assessment1

CLIMEX, a climate-matching model, is described in relation to pest risk assessment. The rationale for the development Of CLIMEX is given and its various functions are illustrated with examples, using the Colorado beetle Leptinotarsa decemlineata. The beetle's climatic requirements are first inferred from its native distribution in North America. They are then used to project the relative favourableness of Europe and Asia for population growth and persistence. The role is illustrated Of CLIMEX, in association with PESKY, a prototype version of a generic expert system for pest risk assessment, in the assessment of the risk of the beetle being transferred from France to China. Finally, CLIMEX is used to search for places in North America with climates best matching that of Beijing (CN), in order to target collection of possible biocontrol agents for use against the beetle in that area, should it become established there.     

Beyond compliance: project on an integrated systems approach for pest risk management in South East Asia

The Beyond Compliance project, which began in July 2011 with funding from the Standards and Trade Development Facility for 2 years, aims to enhance competency and confidence in the South East Asian sub‐region by applying a Systems Approach for pest risk management. The Systems Approach involves the use of integrated measures, at least two of which are independent, that cumulatively reduce the risk of introducing exotic pests through trade. Although useful in circumstances where single measures are inappropriate or unavailable, the Systems Approach is inherently more complicated than single‐measure approaches, which may inhibit its uptake. The project methodology is to take prototype decision‐support tools, such as Control Point‐Bayesian Networks (CP‐BN), developed in recent plant health initiatives in other regions, including the European PRATIQUE project, and to refine them within this sub‐regional context. Case studies of high‐priority potential agricultural trade will be conducted by National Plant Protection Organizations of participating South East Asian countries in trials of the tools, before further modifications. Longer term outcomes may include: more robust pest risk management in the region (for exports and imports); greater inclusion of stakeholders in development of pest risk management plans; increased confidence in trade negotiations; and new opportunities for trade.     

A quantitative model for trade pathway analysis of plant pest entry and transfer to a host in European Union territory

A quantitative pathway model, QPAFood, has been designed to support risk assessment for plant pest entry into European Union (EU) territory on a range of edible plant commodities via trade flows. The model calculates the distribution of an imported infested/infected commodity along a pathway into and within the EU from source countries, based on Eurostat data and other data/information. The model determines the implications of global trade pathways for the potential arrival of the infested commodity in the EU28 Member States. Within each Member State, the calculation proceeds by distributing the commodity according to uses, notably retail or processing, to the vulnerable area of commercial host crops determined in each NUTS2 region and then quantifies the consequent potential for pest–host contact which could lead to pest transfer. Annual and monthly estimates of contact risk are tabulated and visualized for Member States and NUTS2 regions. The model was developed originally for the European Food Safety Authority using four case studies of specific pest–commodity combinations. These pests had relatively limited host ranges and the model has now been extended in the context of the EC FP7 DROPSA project for the multiple commodity pathways associated with the highly polyphagous fruit pest Drosophila suzukii.     

Pest risk analysis for Solanum elaeagnifolium and international management measures proposed

Solanum elaeagnifolium Cav., originating from the Americas, has been unintentionally introduced in all the other continents as a contaminant of commodities, and is considered one of the most invasive plants worldwide. In the Euro‐Mediterranean area, it is a huge threat in North African countries. It is also present in European Mediterranean countries (France, Greece, Italy and Spain), but still has a limited distribution. Through a logical sequence of questions, pest risk analysis (PRA) assessed the probability of S. elaeagnifolium entering, establishing, spreading and having negative impacts in European and Mediterranean countries. As this assessment revealed that the entry of the pest would result in an unacceptable risk, pest risk management options were selected to prevent the introduction of the plant. Preventive measures on plants or plant products traded internationally may directly or indirectly affect international trade. According to international treaties, PRA is a technical justification of such international preventive measures.     

PRATIQUE: a research project to enhance pest risk analysis techniques in the European Union

PRATIQUE is an EC-funded 7th Framework research project designed to address the major challenges for pest risk analysis (PRA) in Europe. It has three principal objectives: (a) to assemble the datasets required to construct PRAs valid for the whole of the EU, (b) to conduct multi-disciplinary research that enhances the techniques used in PRA and (c) to provide a decision support scheme for PRA that is efficient and user-friendly. The research will be undertaken by scientists from 13 institutes in the EU and one each from Australia and New Zealand with subcontractors from institutes in China and Russia. They will produce a structured inventory of PRA datasets for the EU and undertake targeted research to improve existing procedures and develop new methods for (a) the assessment of economic, environmental and social impacts, (b) summarising risk while taking account of uncertainty, (c) mapping endangered areas (d) pathway risk analysis and systems approaches and (e) guiding actions during emergencies caused by outbreaks of harmful organisms. The results will be tested and provided as protocols, decision support systems and computer programs with examples of best practice linked to a computerised European and Mediterranean Plant Protection Organization (EPPO) PRA scheme.     

Bt maize and integrated pest management ‐ a European perspective

The European corn borer (Ostrinia nubilalis), the Mediterranean corn borer (Sesamia nonagrioides) and the western corn rootworm (Diabrotica virgifera virgifera) are the main arthropod pests in European maize production. Practised pest control includes chemical control, biological control and cultural control such as ploughing and crop rotation. A pest control option that is available since 1996 is maize varieties that are genetically engineered (GE) to produce insecticidal compounds. GE maize varieties available today express one or several genes from Bacillus thuringiensis (Bt) that target corn borers or corn rootworms. Incentives to growing Bt maize are simplified farm operations, high pest control efficiency, improved grain quality and ecological benefits. Limitations include the risk of resistance evolution in target pest populations, risk of secondary pest outbreaks and increased administration to comply with licence agreements. Growers willing to plant Bt maize in the European Union (EU) often face the problem that authorisation is denied. Only one Bt maize transformation event (MON810) is currently authorised for commercial cultivation, and some national authorities have banned cultivation. Spain is the only EU member state where Bt maize adoption levels are currently delivering farm income gains near full potential levels. In an integrated pest management (IPM) context, Bt maize can be regarded as a preventive (host plant resistance) or a responsive pest control measure. In any case, Bt maize is a highly specific tool that efficiently controls the main pests and allows combination with other preventive or responsive measures to solve other agricultural problems including those with secondary pests. Copyright © 2011 Society of Chemical Industry     

Exploiting the high‐resolution JRC‐MARS European climatic dataset for pest risk mapping

Climatic data with a high temporal and spatial resolution are invaluable when modelling the potential distribution of non‐native pests. The European Commission Joint Research Centre Monitoring Agricultural ResourceS (MARS) programme provides a unique source of European daily climatic data. Available from 1975 to 2015 and updated annually, the data are interpolated from over 5000 weather stations to 25‐km grid cells. All geographical Europe is included, plus Mediterranean areas of the Middle East and North Africa. The climatic parameters available include temperature (daily minima and maxima), solar radiation, rainfall and relative humidity. As well as the potential for use in simple pest models, selected parameters can be imported into more complex models, such as CLIMEX, for more detailed analyses. Case studies showing how the MARS data have been used by the UK in pest risk analyses are presented for three insect pests: Thaumetopoea pityocampa, Hyphantria cunea (both Lepidoptera) and Popillia japonica (Coleoptera). The case studies illustrate some methods of representing uncertainty where thresholds are lacking in the published literature, there are conflicting data and only air temperature data are available to model a soil‐dwelling organism.     

Ecological aspects of pest risk assessment1

The primary purpose of a national plant protection organization is to prevent the spread of quarantine pests. Such pests are characterized according to their predicted capability to be of economic importance in new areas. The determination of the potential of an exotic pest to cause crop losses is a preliminary component in a pest risk assessment (PRA) process. The initial PRA step includes two distinct ecological analyses. The first must predict the expected extent and frequency to which a new pest population will attain and/or surpass the economic injury level. This is necessary to justify the classification of an exotic pest as being of quarantine significance. Secondly, a PRA must estimate the likelihood of establishment for those quarantine pests for which an entry pathway exists. Both require that bioclimatic comparisons be made between the areas of origin and distinct target destinations. The bioclimatic methodologies of the past are currently being enhanced to specify more precisely‘quarantine pest zones of ecological equivalency’, i.e. areas within which the behavior of a specific quarantine pest can be expected to be the same. The information derived from studies that provide a basis for forecasting the behavior of indigenous pests can also be used in PRA.     

A decision‐support scheme for mapping endangered areas in pest risk analysis*

This paper describes a decision‐support scheme (DSS) for mapping the area where economically important loss is likely to occur (the endangered area). It has been designed by the PRATIQUE project to help pest risk analysts address the numerous risk mapping challenges and decide on the most suitable methods to follow. The introduction to the DSS indicates the time and expertise that is needed, the data requirements and the situations when mapping the endangered areas is most useful. The DSS itself has four stages. In stage 1, the key factors that influence the endangered area are identified, the data are assembled and, where appropriate, maps of the key factors are produced listing any significant assumptions. In stage 2, methods for combining these maps to identify the area of potential establishment and the area at highest risk from pest impacts are described, documenting any assumptions and combination rules utilised. When possible and appropriate, Stage 3 can then be followed to show whether economic loss will occur in the area at highest risk and to identify the endangered area. As required, Stage 4, described elsewhere, provides techniques for producing a dynamic picture of the invasion process using a suite of spread models. To illustrate how the DSS functions, a maize pest, Diabrotica virgifera virgifera, and a freshwater invasive alien plant, Eichhornia crassipes, have been used as examples.     

Modelling and mapping spread in pest risk analysis: a generic approach*

Assessing the likelihood and magnitude of spread is one of the cornerstones of pest risk analysis (PRA), and is usually based on qualitative expert judgment. This paper proposes a suite of simple ecological models to support risk assessors who also wish to estimate the rate and extent of spread, e.g. when modelling the dynamics of invasion and the economic impacts that may result. Models are based on simple ecological principles, such as logistic growth, radial range expansion and population growth in combination with dispersal. Different models capture different perspectives of the spread process, being based on pest density or simply presence/absence, and they compare spatially explicit and spatially implicit approaches. A case study on Diabrotica virgifera virgifera is provided for illustration. The suite of models requires further development and testing with the risk assessment community building familiarity before their more general application in PRA.     

The challenge of providing plant pest diagnostic services for Africa

The consequences of a globalisation of trade and climate change present an increased threat from first-entry pests and a challenge to plant health authorities. In this paper, pest reporting for the continents of Africa and Europe are discussed, and argued as a barometer of effective Plant Pest Diagnostic Services (PPDS) in terms of human capacity, infrastructure and policy-culture for phytosanitary issues. To illustrate particular areas of concern, case studies are presented on recent pest events which include outbreaks of Ralstonia solanacearum on Pelargonium, Xanthomonas campestris pv. musacearum on banana (banana Xanthomonas wilt) and Puccinia graminis f.sp. tritici race Ug99 on wheat (black stem rust). Examples are given of some recent initiatives to invigorate diagnostic capacity in East Africa, spanning state-of-the-art centres of excellence, traditional capacity building and networking projects, and grass-root level 'going-public' pest surveillance initiatives. Discussion is presented on the provision of PPDS and the impact of technology, institutional factors, the private sector, accreditation of services and policy. Emphasis is placed on the role of PPDS in support of regulatory policy. In recognising the precarious nature of many African cropping systems, the argument is made for a more consolidated approach to PPDS in and for Africa. The paper is presented from the perspective of European practitioners in pest diagnostic and risk analysis.     

Spirodiclofen and spirotetramat bioassays for monitoring resistance in citrus red mite, Panonychus citri (Acari: Tetranychidae)

BACKGROUND: Citrus red mite, Panonychus citri (McGregor), is a key pest of San Joaquin Valley California citrus. Spirodiclofen was registered for mite control in 2007, and spirotetramat for scale control in 2008. Because of the potential for resistance to spirodiclofen to develop in spider mites, and cross‐resistance to spirotetramat used for other citrus pests, bioassay methods for resistance monitoring were developed. RESULTS: The responses of four populations of adult female, egg and larval stages of P. citri to spirodiclofen were compared to determine the most robust bioassay method for this pesticide. Adult females responded with a higher LC₉₉ and larval stages exhibited higher control mortality and a lower slope of response compared with the egg stage. Thus, the egg stage was found to be the most suitable stage for testing. Egg production and egg shape were significantly affected by spirodiclofen treatment of adult female mites. Bioassays with the related compound spirotetramat revealed that P. citri egg hatch was less affected by this compound, requiring the assessment of mortality to be extended to 11 days after treatment when the hatched larvae succumbed to the pesticide. Discriminating concentrations of 10 ppm for spirodiclofen and 31.6 ppm for spirotetramat in an 11 day bioassay were tested against eight field populations of P. citri, and 99–100% mortality resulted. CONCLUSION: These results provide a baseline for the response of P. citri to spirodiclofen and spirotetramat that will aid resistance management in California citrus. Copyright © 2011 Society of Chemical Industry     

The EFSA assessment of Trichilogaster acaciaelongifoliae as biocontrol agent of the invasive alien plant Acacia longifolia: a new area of activity for the EFSA Plant Health Panel?

This paper summarizes the first assessment by the European Food Safety Authority (EFSA) Plant Health (PLH) Panel of a biological control agent (BCA) of an invasive plant. This followed a request by the European Union (EU) Commission to assess the risk to plant health in the EU of an intentional release of the bud‐galling wasp Trichilogaster acaciaelongifoliae for the control of Acacia longifolia. The EFSA PLH Panel also published a statement on the process of assessing the risk of the intentional releases of BCAs of invasive alien plants. Trichilogaster acaciaelongifoliae feeds on A. longifolia and Acacia floribunda. Acacia longifolia is an invasive alien plant species that has a negative effect on biodiversity and ecosystems in Portugal, whereas A. floribunda is not invasive in the EU. Both species are cultivated as ornamental plants in some EU countries. Climatic conditions in the EU are suitable for establishment of T. acaciaelongifoliae where host species are present. This BCA is moderately likely to spread in the EU by natural means, but could be intentionally moved to control A. longifolia in other locations. Its potential effects on invasive A. longifolia and on the cultivated ornamentals were assessed. The EFSA PLH Panel has shown with this work how such advice could be provided in the European Union.     

Report of a rapid pest risk analysis for Lambdina fiscellaria (Guenée, [1858]) (Lepidoptera: Geometridae) for the island of Ireland

The hemlock looper, Lambdina fiscellaria (Guenée), is a serious forest pest in North America with three subspecies that vary in their geographical range and larval host preferences. Both broadleaved and coniferous trees are infested, though the largest impacts are on coniferous forestry where trees can be completely defoliated and killed. The pest was identified as a potential threat to forestry on the island of Ireland during a horizon‐scanning exercise to identify pests of Picea sitchensis (Bong.) Carr. (Sitka spruce) and was subject to a rapid pest risk analysis (PRA). Though judged to be unlikely, pathways identified were uncontrolled wood commodities and mosses and lichens harvested from forests in North America and exported for use in ornamental displays. Lambdina fiscellaria is found in a range of climate types, and is likely to be able to complete its lifecycle in the Irish climate – although there is uncertainty concerning its ability to adapt to European trees. Lambdina fiscellaria has only a limited capacity for spread, as virgin females are burdened by their eggs and are poor fliers. This was judged to reduce potential impacts in the PRA area – as the slow rate of spread would provide time to develop monitoring and control methods well ahead of the pest reaching its maximum extent on the island of Ireland. The pest still poses a considerable risk to coniferous forestry not only on the island of Ireland but across the EPPO region where climate is suitable for the pest to establish. Regulation and implementation of phytosanitary measures prevent introduction of the pest should be considered.     

Common vole (Microtus arvalis) ecology and management: implications for risk assessment of plant protection products

Common voles (Microtus arvalis) are common small mammals in some European landscapes. They can be a major rodent pest in European agriculture and they are also a representative generic focal small herbivorous mammal species used in risk assessment for plant protection products. In this paper, common vole population dynamics, habitat and food preferences, pest potential and use of the common vole as a model small wild mammal species in the risk assessment process are reviewed. Common voles are a component of agroecosystems in many parts of Europe, inhabiting agricultural areas (secondary habitats) when the carrying capacity of primary grassland habitats is exceeded. Colonisation of secondary habitats occurs during multiannual outbreaks, when population sizes can exceed 1000 individuals ha^?1. In such cases, in‐crop common vole population control management has been practised to avoid significant crop damage. The species' status as a crop pest, high fecundity, resilience to disturbance and intermittent colonisation of crop habitats are important characteristics that should be reflected in risk assessment. Based on the information provided in the scientific literature, it seems justified to modify elements of the current risk assessment scheme for plant protection products, including the use of realistic food intake rates, reduced assessment factors or the use of alternativee focal rodent species in particular European regions. Some of these adjustments are already being applied in some EU member states. Therefore, it seems reasonable consistently to apply such pragmatic and realistic approaches in risk assessments for plant protection products across the EU. © 2013 Society of Chemical Industry     

Lethal and sub-lethal effects of a novel sulfoximine insecticide,sulfoxaflor, against Asian citrus psyllid and its primary parasitoid under laboratory and field conditions

The Asian citrus psyllid, Diaphorina citri Kuwayama, is the most important international pest of citrus because it transmits the bacteria that cause huanglongbing (HLB). HLB limits citrus production globally. We evaluated the toxicity of sulfoxalor against D. citri and its parasitoid, Tamarixia radiata Waterston. Sulfoxaflor was as toxic as imidacloprid to adult D. citri. The LC₅₀ values for sulfoxaflor and imidacloprid were 8.17 and 5.7 µg AI mL^?1, respectively. The LC₅₀ of sulfoxaflor for T. radiata adults was 3.3 times greater than for D. citri adults. Treatment with sulfoxaflor resulted in reduced oviposition, development of nymphs, and emergence of adult D. citri on plants, as compared with controls. The lowest concentration that reduced adult emergence was 0.6 µg AI mL^?1. There was reduced feeding by D. citri adults on leaves treated with sulfoxaflor. The residual toxicity of sulfoxaflor was equivalent to imidacloprid. Under field conditions, formulated sulfoxaflor reduced populations of D. citri compared with untreated controls. Sulfoxaflor is a novel mode of action and is an effective tool for D. citri management.     

丽草蛉对柑橘木虱成虫的捕食功能反应及捕食偏好

为明确丽草蛉Chrysopa formosa对柑橘木虱Diaphorina citri成虫的生物防控潜能,在实验室条件下测定丽草蛉1、2、3龄幼虫和成虫对柑橘木虱成虫的捕食功能、搜寻效应及其种内干扰效应,并测定其对不同猎物的捕食偏好。结果显示,丽草蛉1～3龄幼虫和成虫对柑橘木虱成虫均有捕食行为,捕食功能反应均符合Holling II模型。丽草蛉1、2、3龄幼虫和成虫对柑橘木虱成虫的瞬时攻击率分别为0.247、0.393、0.769和0.509,处理时间分别为0.228、0.048、0.015和0.013 d,理论日最大捕食量分别为4.386、20.833、66.667和76.923头,控害效能分别为1.083、8.188、51.267和39.154。各虫态丽草蛉对柑橘木虱成虫的搜寻效应均随着猎物密度的增加而降低,其中3龄丽草蛉幼虫的搜寻效应下降趋势最大。当柑橘木虱成虫密度固定时,单头丽草蛉的日捕食量随柑橘木虱密度的增加而逐渐降低,其捕食作用受到自身密度的干扰,干扰效应方程为E=0.260P-0.351。当存在柑橘木虱与豌豆蚜Acyrthosiphon pisum两种捕食对象时,丽草蛉3...