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Pests and diseases greatly contribute to the decline in banana yields, food and income insecurity in the Great Lakes region of Africa. Understanding people’s role in pest and disease spread at landscape level is crucial for effective pest and disease management. To determine this, focus group discussions (FGDs) targeting 10 experienced farmers (50% female and 50% male) were conducted in 27 villages along four banana trade routes in western Burundi and eastern DR Congo. FGDs determined the presence and risk of spread of key banana pests and diseases via the movement of banana bunches, planting material and other products, labourers, traders and farm tools. Black leaf streak (BLS), Fusarium wilt and banana bunchy top disease (BBTD) were reported to have been in the landscape for over 40 years while Xanthomonas wilt (XW) was a more recent introduction (1-7 years). BBTD, XW and weevils were the most prevalent constraints. BBTD was observed at previously unsuitable high-altitude zones, which should be a cause of concern, especially with the current risk of climate change. Climate change, and linked temperature increases, could also worsen the prevalence of XW, weevils, nematodes and BLS. Movement of farming tools by labourers and traders, of planting material/suckers and banana bunches emerged as the most common human practices potentially responsible for the spread and/or build-up of banana pests/diseases. Strengthening farmer’s knowledge and institutional capacities of actors on these different modes of disease spread in banana value chains in the region is recommended. Key words: Black leaf streak, bunchy top disease, Fusarium wilt, nematodes, weevils, Xanthomonas wilt.

The serious damages of Xylella fastidiosa (Xf) in Euro-Mediterranean countries (e.g. Italy, France, Spain) raise concerns for the Near East and North Africa (NENA). Therefore, a study was performed to a) assess the risk of Xf entry, establishment and spread in target NENA countries (viz. Algeria, Egypt, Jordan, Lebanon, Libya, Morocco, Palestine, Syria, Tunisia); b) analyze risk perception and preparedness level among agri-food chain stakeholders; c) estimate potential socio-economic impacts for olives, grapes and citrus. Pest risk appraisal suggests that Morocco, Lebanon, Palestine and Syria are the most exposed to Xf risk; other target NENA countries, except Algeria, have an intermediate risk. Risk perception analysis shows that governance efficacy and practices application can be improved by involving stakeholders and raising their awareness. Socio-economic impact assessment indicates declining yields, production, profitability, export, employment, and increasing import, with the highest impacts relating to olives, then citrus and grapes. The study suggests that the expected socio-economic impacts are unacceptable and require urgent action against Xf at national and regional levels.

In order to prevent and control the emergence of biosecurity threats such as vector-borne diseases of plants, it is vital to understand drivers of entry, establishment, and spatiotemporal spread, as well as the form, timing, and effectiveness of disease management strategies. An inherent challenge for policy in combatting emerging disease is the uncertainty associated with intervention planning in areas not yet affected, based on models and data from current outbreaks. Following the recent high-profile emergence of the bacterium Xylella fastidiosa in a number of European countries, we review the most pertinent epidemiological uncertainties concerning the dynamics of this bacterium in novel environments. To reduce the considerable ecological and socio-economic impacts of these outbreaks, eco-epidemiological research in a broader range of environmental conditions needs to be conducted and used to inform policy to enhance disease risk assessment, and support successful policy-making decisions. By characterizing infection pathways, we can highlight the uncertainties that surround our knowledge of this disease, drawing attention to how these are amplified when trying to predict and manage outbreaks in currently unaffected locations. To help guide future research and decision-making processes, we invited experts in different fields of plant pathology to identify data to prioritize when developing pest risk assessments. Our analysis revealed that epidemiological uncertainty is mainly driven by the large variety of hosts, vectors, and bacterial strains, leading to a range of different epidemiological characteristics further magnified by novel environmental conditions. These results offer new insights on how eco-epidemiological analyses can enhance understanding of plant disease spread and support management recommendations. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

Xylella fastidiosa is the causal agent of plant diseases that cause massive economic damage. In 2013, a strain of the bacterium was, for the first time, detected in the European territory (Italy), causing the Olive Quick Decline Syndrome. We simulate future spread of the disease based on climatic-suitability modeling and radial expansion of the invaded territory. An economic model is developed to compute impact based on discounted foregone profits and losses in investment. The model projects impact for Italy, Greece, and Spain, as these countries account for around 95% of the European olive oil production. Climatic suitability modeling indicates that, depending on the suitability threshold, 95.5 to 98.9%, 99.2 to 99.8%, and 84.6 to 99.1% of the national areas of production fall into suitable territory in Italy, Greece, and Spain, respectively. For Italy, across the considered rates of radial range expansion the potential economic impact over 50 y ranges from 1.9 billion to 5.2 billion Euros for the economic worst-case scenario, in which production ceases after orchards die off. If replanting with resistant varieties is feasible, the impact ranges from 0.6 billion to 1.6 billion Euros. Depending on whether replanting is feasible, between 0.5 billion and 1.3 billion Euros can be saved over the course of 50 y if disease spread is reduced from 5.18 to 1.1 km per year. The analysis stresses the necessity to strengthen the ongoing research on cultivar resistance traits and application of phytosanitary measures, including vector control and inoculum suppression, by removing host plants., This work was supported by funding from the EU’s Horizon 2020 Pest Organisms Threatening Europe research and innovation program under Grant 635646. M.C. held an Institut Valencià d’Investigacions Agràries grant partially funded by the European Social Fund Comunitat Valenciana 2014–2020.

Background The Siberian moth (Dendrolimus sibiricus) is a serious pest of conifers in Russia, Northern Kazakhstan, Mongolia and China. The western border of the pest’s distribution in Russia is disputed, but it is present west of the 60th meridian east. The pest has the potential to defoliate a wide range of conifers. Results The pest is not present in Norway or other European countries, except Russia. Natural spread and human mediated transport are potential pathways for the pest. Human mediated pathways considered are: Living trees for planting, coniferous wood in the rough and foliage and branches. There has been no import of living trees from Russia to Norway during the past 30 years, and there is currently no import of coniferous wood commodities containing bark from areas, where D. sibiricus occurs. Conclusions The probability of D. sibiricus entry by natural spread is unlikely, mainly because of the geographical distance and the partial sea barriers between Norway and the infested areas. The probability of entry by human mediated pathways is unlikely due to the very limited volume of the import. Should the pest enter Norway, the probability of establishment and spread is unlikely, due to the suboptimal climatic conditions, and the fact that the two dominant conifers in the country, Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), are intermediate and poor hosts, respectively. The potential damage, should D. sibiricus enter Norway, is considered low.

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.Journal of Nepal Agricultural Research Council Vol.3 2017: 32-37

International audience; The international seed trade is considered relatively safe from a phytosanitary point of view and is therefore less regulated than trade in other plants for planting. However, the pests carried by traded seeds are not well known. We assessed insects and fungi in 58 traded seed lots of 11 gymnosperm and angiosperm tree species from North America, Europe, and Asia. Insects were detected by X-raying and molecular methods. The fungal community was characterized using high-throughput sequencing (HTS) and by growing fungi on non-selective agar. About 30% of the seed lots contained insect larvae. Gymnosperms contained mostly hymenopteran (Megastigmus spp.) and dipteran (Cecidomyiidae) larvae, while angiosperms contained lepidopteran (Cydia latiferreana) and coleopteran (Curculio spp.) larvae. HTS indicated the presence of fungi in all seed lots and fungi grew on non-selective agar from 96% of the seed lots. Fungal abundance and diversity were much higher than insect diversity and abundance, especially in angiosperm seeds. Almost 50% of all fungal exact sequence variants (ESVs) found in angiosperms were potential pathogens, in comparison with around 30% of potentially pathogenic ESVs found in gymnosperms. The results of this study indicate that seeds may pose a greater risk of pest introduction than previously believed or accounted for. A rapid risk assessment suggests that only a small number of species identified in this study is of phytosanitary concern. However, more research is needed to enable better risk assessment, especially to increase knowledge about the potential for transmission of fungi to seedlings and the host range and impact of identified species.

Following a series of requests for scientific advice from the European Commission starting in 2013, the European Food Safety Authority (EFSA) conducted a pest risk assessment and created a comprehensive Xylella fastidiosa host plant database. The last update of the database, published in September 2018, includes information on host plants of both X. fastidiosa and X. taiwanensis, together with details on botanical classification, infection conditions, geographic location, pathogen taxonomy including information on subspecies, strain and sequence type, detection techniques, and tolerant/resistant response of the plant. This updated database of host plants of Xylella spp. reported worldwide provides a key tool for risk management, risk assessment, and research on this generalist bacterial plant pathogen.

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.

In 2006, US Department of Agriculture Animal and Plant Health Inspection Service published a landmark rule providing generic radiation quarantine treatments. The rule approved radiation doses of 150 Gy for any tephritid fruit fly and 400 Gy for all other insects except the pupa and adult stages of Lepidoptera. The generic radiation treatments apply to all fresh horticultural commodities. Therefore, if a pest risk assessment demonstrates that no pupae or adult Lepidoptera are associated with a commodity, export approval can be forthcoming with no further research. Generic treatments are the culmination of decades of research but not an end point. Future research on quarantine and phytosanitary uses of radiation should focus on (1) development of specific doses for quarantine Lepidoptera not covered by the generic treatments, (2) reduction of dose levels for specific pests and commodities to shorten treatment time and minimize any deleterious effects of radiation treatment on commodity quality, (3) development of generic doses below 400 Gy for important groups of quarantine arthropods other than fruit flies, and (4) development of information on commodity tolerance and development of value-added irradiated fresh products using generic radiation treatments. Generic treatments will facilitate safe trade between countries that have approved phytosanitary uses of radiation for fresh agricultural commodities.

Pest risk assessment studies are aimed at evaluating if weather conditions are suitable for the potential entry and establishment of an organism in a new environment. For fungal plant pathogens, the crucial aspect to be explored is the fulfillment of the infection process, that constitutes the first phase of the development of an epidemic as mainly driven by temperature and leaf wetness duration. This is of particular interest for climate change studies, because the modified pattern of temperature and moisture regimes could completely alter the known distribution and severity of plant disease epidemics. Biophysical process-based models could effectively be used in such studies, because they allow, within their applicability range, estimating organisms responses to climatic drivers in environmental conditions not yet experienced. One of the prerequisite of their adoption in operational contexts is a sensitivity analysis assessment aimed at understanding their ability (i) to differentiate the responses according to different parameterizations and (ii) to be sensitive to the variability of the input data. In this study, a generic potential fungal infection model simulating four pathogens chosen to provide a wide range in temperature and moisture requirements was analyzed. The model was run under diverse climatic conditions. The sensitivity of the model significantly changed according to the pathogen tested, and the relevance of its parameters in explaining model output resulted strongly linked to the environmental conditions tested, indicating its to be used in pest risk assessment studies.

Epitrix tuberis and E. cucumeris are major pests of potatoes in North America. E. tuberis causes the most serious damage because the larval feeding can cause superficial serpentine tunnelling on the surface of tubers as well as deeper pits. This damage can make crops unmarketable. By contrast, E. cucumeris mainly damages the foliage, and yield losses can occur when the adults reach high densities. In 2004, potato tuber damage characteristic of E. tuberis was seen in Portugal. In 2008, damage was more widespread and severe. E. cucumeris and a lesser known species, E. similaris, were recorded in affected fields. E. similaris has since been found across Galicia, Spain. E. similaris is thought to be the most likely cause of the tuber damage in Portugal, but it is possible that E. cucumeris or an as yet undetected Epitrix species is causing the damage. In 2010, a pest risk assessment for the Euro-Mediterranean area identified the movement of adults and pupae with seed or ware potatoes and associated soil as being the highest-risk pathways for the spread of Epitrix. In 2012, EU emergency measures were agreed to reduce the risk of further introductions and the rate of spread of these pests.

Liriomyza huidobrensis (Blanchard) is an economically important and highly polyphagous worldwide pest. To establish a temperature-dependent phenology model, essential for understanding the development and growth of the pest population under a variety of climates and as part of a pest risk analysis, L. huidobrensis life-table data were collected under laboratory conditions at seven constant temperatures on its host faba bean (Vicia faba L.). Several nonlinear equations were fitted to each life stage to model the temperature-dependent population growth and species life history and finally compile an overall temperature-dependent pest phenology model using the Insect Life Cycle Modeling (ILCYM) software. Liriomyza huidobrensis completed development from egg to adult in all temperatures evaluated, except at 32 °C, which was lethal to pupae. Eggs did not develop at 35 °C. Mean development time of all immature stages decreased with increasing temperature. Nonlinear models predicted optimal temperature for immature survival between 20–25 °C (32–38% mortality of all immature stages). Life-table parameters simulated at constant temperatures indicated that L. huidobrensis develops within the range of 12–28 °C. Simulated life-table for predicting the population dynamics of L. huidobrensis under two contrasting environments showed that lowland temperatures at the coast of Peru (250 m.a.s.l.) presented better conditions for a potential population increase than highland (3,400 m.a.s.l.) conditions. The presented model linked with Geographic Information Systems will allow pest risk assessments in different environmental regions to support the regulation of pest movement to prevent pest entry into not-yet invaded regions as well as to implement effective management strategies.

Host area, potential pest impact and probability of pest presence are frequently displayed on maps by pest risk assessors. These variables can be mapped separately, but it is also important to map combinations of these variables in order to define the area of potential establishment and the endangered area to assist decision-making processes. This paper presents different methods for combining maps, and discusses their advantages and disadvantages. Different methods are shown that can be used to combine maps depending on whether the individual maps were derived from continuous quantitative variables or from discrete variables. The authors suggest combining maps derived from continuous variables using simple mathematical equations in order to compute expected invaded areas and expected potential impacts. Maps derived from discrete variables (e.g. scores) can be combined using a risk matrix, but the results may be highly dependent on the chosen matrix. The practical interest of these methods is illustrated in a case study on Diabrotica virgifera virgifera. The authors recommend combining the original continuous variables when such variables are available. The combination of categories defined from continuous variables led to a loss of information and may decrease the values of the maps. Risk matrices should be used only if the individual variables are discrete and if the underlying continuous variables are not available.

The phytosanitary risk associated with the movement of export-quality apple fruit to countries where fire blight does not occur is reassessed based upon additional data available since 1998 and clarification or correction of previously misinterpreted data present in the literature. The low epiphytic fitness of Erwinia amylovora (Ea) on apple fruit, the documented low incidence of viable Ea populations on mature apple fruit and the lack of a documented pathway by which susceptible host material could become infected from fruit-borne inoculum remain unchanged, and support the view that movement of Ea via commercial apple fruit is highly unlikely. With this new information, we updated a previously published model to re-estimate the likelihood of fire blight outbreaks in new areas because of commercial fruit shipment. This likelihood decreased in every scenario, and ranged from one outbreak in 5217 years to one in 753,144 years. By using the corrected and newly published data and by making assumptions based upon documented pathogen biology, the model gives more robust statistical support to the opinion that the risk of importing Ea on commercial apple fruit and the concomitant risk of establishing new outbreaks of fire blight is so small as to be insignificant.

The estimation of rates and patterns of spread is one of the key steps in a pest risk assessment. Pest risk analysts across the world wish to make quantitative, scientifically defensible assessments of likely spread by invasive alien species. However, data and time to develop detailed models for pest invasions are usually lacking and the resources to test those models in practice are not available. Therefore, generic and simple models are needed. A generic spread module composed of four models has been developed to assess the spread of plant pests. Four different models were developed to represent differences in objectives, available data and assumptions underlying the assessment of spread. The most complex of the models simulates spread in time and space and has four biological parameters, representing population growth and dispersal. The simplest of the models has only one parameter and considers only geographic range expansion. A third model assumes logistic growth of invaded area and a fourth model assumes logistic growth of population density in invaded cells. All models consider climatic suitability and presence of hosts. Consideration of economic value is optional. This chapter describes concepts and application of these models. They are illustrated by case studies for western corn rootworm, Diabrotica virgifera virgifera, in Europe.

The invasion risk posed by the xylem feeding hemipteran, Homalodisca coagulata (native to the southeast USA and northeast Mexico, and a recent invader of California (USA) and Tahiti) and a xylem-dwelling phytopathogenic bacterium, Xylella fastidiosa (native to the Americas and causative agent of Pierce's disease of grape vines), was examined using the computer climate modeling program CLIMEX. Model predictions indicated that suitable climatic conditions for H. coagulata and Pierce's disease causing strains of X. fastidiosa exist in almost all grape production areas of the world, and H. coagulata may be able to colonize areas unsuitable for X. fastidiosa. Additionally, the model indicated that regions north of California will be unable to sustain populations of both pests because of cold stress, and that irrigation of agricultural and urban areas in California's deserts has removed dry stress limitations, which when combined with a depauperate natural enemy fauna most likely facilitated successful invasion by H. coagulata. CLIMEX predicted that cold stress accumulation would exclude Pierce's disease causing strains of X. fastidiosa from France and northern and central grape producing areas of Spain and Italy. This result is incongruous with Pierce's disease reports from Kosovo in the Balkans and may suggest that cold-tolerant strains of X. fastidiosa that cause Pierce's disease exist which could exhibit invasion potential and establish in areas of Europe contrary to results reported here.

Four main characters are associated with the potential of Lymantria dispar for international spread in ships moving from the Russian Far East to other Pacific countries: movement to light, wind dispersal of young larvae, length of egg stage, host range of larvae. Other Far Eastern lymantriid species have been scored for these characters on a 1-5 scale to provide an estimate of the risk of such international spread. Lymantria spp. score highest on this scale, and a few other lymantriids have scores indicating that there is a definite risk. Most of the species scored cannot, however, be adequately assessed for all the characters because of lack of information, indicating the need for further research before an adequate pest risk assessment can be done.

Increasing world trade in unmanufactured wood articles has amplified the risks of inadvertent introduction of pests into new environments. Previous introductions of non-native invasive organisms into the United States have resulted in severe outbreaks with economic and ecological disruption in forests. The United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) and the USDA Forest Service have developed a pest risk assessment process that attempts to identify the risks associated with importation of unmanufactured wood articles. Assessments have been completed for importation into the United States of logs from Russia, New Zealand, Mexico, and South America. The results of these assessments are considered in developing regulatory approaches to preventing introductions of non-native invasive organisms.

The Panel conducted a risk assessment of Phyllosticta citricarpa for the EU. P. citricarpa causes citrus black spot (CBS) and is absent from the EU. Under the scenario of absence of specific risk reduction options against P. citricarpa, the risk of entry of P. citricarpa was rated as likely for citrus plants for planting and citrus fruit with leaves, moderately likely for citrus fruit without leaves, unlikely for citrus leaves for cooking and very unlikely for Tahiti lime fruit without leaves. Establishment was rated as moderately likely because susceptible hosts are widely available and environmental conditions in many EU citrus-growing areas are suitable (with high uncertainty) for P. citricarpa ascospore production, dispersal and infection. Current fungicide treatments will not prevent establishment. Environmental favourability is increased by the use of sprinkler and micro-sprinkler irrigation in some EU citrus-growing locations. Spread with trade was rated as moderately likely. Model results indicate that CBS epidemics are most likely to develop in EU citrus-growing areas in late summer to early autumn and in some locations also in late spring to early summer. CBS is expected to affect mainly lemons and late-maturing sweet orange and mandarin varieties, with moderate negative consequences for the production of fresh fruit, but with environmental impact of additional fungicide treatments. Negative consequences would be minor for early-maturing citrus varieties and minimal for citrus for processing. Uncertainty concerning the consequences is high, mainly because of the lack of data on critical climate response parameters for the pathogen but also because information on impact in areas at the limits of the current distribution is scarce. Since eradication and containment are difficult, phytosanitary measures should focus on preventing entry. Current phytosanitary measures are evaluated to be effective, with the exception of pest-free production sites.

The Panel on Plant Health assessed the risk to plant health from Phytophthora fragariae for the European Union and evaluated the current EU legislation and possible risk reduction options. The pest is present in most areas of Europe except southern Mediterranean regions. Entry through the plants for planting, but not seeds, pathway, is assessed as a major pathway, with the probability of entry rated as unlikely and the uncertainty as high. The probability of establishment is likely in the absence of existing disease control practices with low uncertainty. The probability of spread in the absence of a scheme for the production of certified plants for planting is considered to be very likely. With certification, spread is considered to be unlikely to moderately likely, depending on the inclusion of testing for the pathogen as part of certification. These ratings have medium uncertainty. Potential impact is rated as minor with medium uncertainty. The Panel evaluated the effectiveness of current EU legislation regarding the introduction and spread of P. fragariae. According to the regulation the import of Fragaria plants for planting, other than seeds, is prohibited from specified countries, whereas for import of these plants from other countries and for movement of these plants within the EU special requirements with respect to P. fragariae must be fulfilled. If the current legislation specific to P. fragariae were removed, no major consequences would be expected, unless the industry simultaneously ceased its voluntary certification activity. This is largely because of the important level of protection afforded to the industry by the widely used certification schemes for Fragaria, which significantly reduce the risks of entry, establishment, spread and impact. Certification schemes for the movement of Fragaria plants for planting offer the greatest efficiency and feasibility and the least uncertainty, especially if effective detection is incorporated into them.

The Scientific Panel on Plant Health (PLH) of the European Food Safety Authority was established in 2006 as the reference EU body for risk assessment in the plant health area in the frame of phytosanitary measures to prevent the introduction and further spread of organisms harmful (pests) to plants or plants products. Proper diagnosis and detection are critical for the categorization and assessment of pests that are or may qualify as quarantine pests, and for appropriate application of phytosanitary measures. In carrying out its responsibilities, the PLH Panel is frequently faced by the changes in taxonomy and nomenclature: these may often lead to a re-evaluation of previous pest records, concerns with published literature, and in some cases with the increased use of molecular taxonomic and identification tools. Pathogens that were previously considered strains/varieties of a single species, in some cases have now been elevated to specific status. In other cases pathogens previously recognised as species complexes have now been partitioned into named species, using molecular criteria rather than traditional methods. The problems that can arise are illustrated in this Chapter by examples representative of the main pathogen taxa.

A survey of the floors of 3001 empty sea cargo containers in storage was undertaken to estimate the quarantine risk of importing exotic insect pests into Australia, with special reference to pests of timber. More than 7400 live and dead insects were collected from 1174 containers. No live infestations of timber-feeding insects were recorded, but feeding damage detected in one floor indicates a low risk of importing colonies of timber pests in containers. The survey collection of dead insects demonstrates that containers are regularly exposed to economically important quarantinable insects, including timber pests (bostrichids, curculionids, cerambycids, siricids and termites), agricultural pests (including Adoretus sinicus, Adoretus sp., Carpophilus obsoletus and Philaenus spumarius), and nuisance pests (vespids and Solenopsis sp.). Stored product pests were found in more than 10% of containers. The assessment of pest risk associated with shipping containers is discussed in terms of the quantity and quality of opportunities for exotic insects to establish via this pathway.

A pest risk assessment was performed according to the EPPO Standard PM 5/3 to determine the probability of introduction of Monilinia fructicola into the countries of the European Union (EU) and its potential economic impact. Data on the biology of the pathogen were combined with trade pathways and information on the use of commodities in order to quantify risk. On the basis of the EPPO Standard, we concluded that there is a serious risk that M. fructicola could become established in the EU, with significant economic losses as a result. This justifies the phytosanitary measures currently in place in the EU.

Organisms generally become pests at a low rate. As a consequence of this low ‘base-rate probability’, the large majority of organisms rejected in any random sample of potential introductions would probably be harmless, despite the fairly high accuracy of some recently proposed risk assessment systems for exotic introductions. Here we distinguish between a system's accuracy (the proportion of a group of known pest species that would be correctly identified as pests) and reliability (the rate of false positives and false negatives produced once the base-rate is taken into account). We next adapt a decision theory analysis of earthquake prediction to explore when we would be best advised to ignore the recommendations of a screening system for exotic introductions. In one scenario, we show that a pest risk assessment system with an accuracy of 85% would be better ignored, unless the damage caused by introducing a pest is eight times or more that caused by not introducing a harmless organism that is potentially useful. Furthermore, because of the base-rate effect, in certain situations it may be more efficient to focus on identifying potential invaders from amongst already naturalized species than from amongst species at the importation stage.

The Panel on Plant Health conducted a pest risk assessment for Bemisia tabaci and the viruses it transmits, including an evaluation of risk reduction options and an assessment of the effectiveness of the special requirements linked to B. tabaci and the viruses listed in Council Directive 2000/29/EC. B. tabaci and a large number of viruses transmitted by this polyphagous insect occur in subtropical and tropical climates around the world. Five entry pathways for B. tabaci and associated viruses were identified, with the plants for planting pathway being most significant and rated for entry of insects and viruses as likely and moderately likely, respectively. The most invasive B. tabaci species and several of its associated viruses responsible for severe diseases in major European food crops are established outdoors in coastal Mediterranean regions. Because of similar climate requirements and host plant preferences, B. tabaci and associated viruses currently not present in Europe are likely to establish within the temperature limits set for B. tabaci. Trade between European Member States allows B. tabaci to reach greenhouses in northern Europe, including those in areas with protected zone status. Because of the cool climate, establishment and spread outdoors of B. tabaci is rated unlikely for northern Europe. This situation is likely to continue even under a climatic scenario with an increase in temperature of +2 °C. B. tabaci -transmitted viruses cause severe diseases with major negative impact on crop production when risk reduction measures are not used. Risk reduction options will also apply to B. tabaci and viruses new to Europe. Risk reductions options are evaluated in terms of reducing B. tabaci populations, crop infestations, virus incidence and the impact of diseases. © European Food Safety Authority, 2013

The Panel on Plant Health conducted a pest risk assessment for Eutetranychus orientalis in the European Union (EU) and evaluated the effectiveness of phytosanitary measures in Council Directive 2000/29/EC. Entry through the plants for planting pathway is assessed as very likely, while entry through other pathways is estimated as moderately likely to unlikely owing to the different probability of transfer to a suitable host. Establishment is rated as very likely in Mediterranean areas and from moderately likely to unlikely in non-Mediterranean areas, because of unfavourable environmental conditions. Spread is rated as very likely because of the many ways the pest can spread, its polyphagy and the wide distribution of hosts. Impact is rated as minor, with an expected increase in the damage when populations of natural enemies are severely affected by control measures and/or when environmental conditions are stressful for the host. However, the lack of information resulted in an overall medium level of uncertainty. The Panel evaluated the effectiveness of current EU phytosanitary measures and concluded that the removal of E. orientalis from Annex IIAII would not affect its probability of entry, because the importation from Third countries of some host plants regulated for this pest(Citrus, Fortunella, Poncirus species and their hybrids) is prohibited in Annex III. However, spread could be affected since there would no longer be a requirement to inspect for this pest before issuing a plant passport (Annex V). However, since the regulated Rutaceae species constitute an extremely small proportion of the potential host plants of E. orientalis, the current phytosanitary measures are mostly ineffective in preventing further introduction and spread of E. orientalis in the EU. The Panel identified surveillance at the production site and treatment of the consignment as the most effective and technically feasible risk reduction options, particularly when applied together.

The Panel on Plant Health conducted a pest risk assessment for Liriomyza huidobrensis and Liriomyza trifolii in the European Union and identified and evaluated the phytosanitary measures listed in Council Directive 2000/29/EC. Entry on the principal pathways (plants for planting, cut flowers and leafy vegetables) is assessed as likely as the pests are regularly associated with the pathways at origin, survival during transport or storage is high and only partially affected by current pest management procedures, and transfer to a suitable host is likely as their hosts are so widespread. Establishment is rated as very likely because both species have established populations in most countries of the EU, with transient populations occurring outdoors in non-Mediterranean areas. Spread within the EU is considered to be likely because the pests can readily be moved with plant material. The magnitude of the potential consequences is rated as minor for both species in Mediterranean areas. In non-Mediterranean countries it is moderate for both species in protected crops but, outdoors, impacts are minor for L. huidobrensis and minimal for L. trifolii. The current regulations to prevent entry and spread were found to be only partially effective as interceptions are still being made, cut branches with foliage and leafy vegetables other than celery are excluded, and the methods for inspection and the treatments required to confirm pest free areas, places of production and consignments are not clearly specified. Removal of the legislation would have some advantages and disadvantages but may not have a major effect. The regulations could be tightened by including additional commodities, clearly prescribing the inspection procedures and the appropriate treatments to be used and combining these with other measures, e.g. screening. The application of protected zones to areas where the pests are not yet present can be applied to help prevent further spread. © European Food Safety Authority, 2012

The Panel on Plant Health conducted a pest risk assessment for Chrysanthemum stunt viroid (CSVd) and identified and evaluated risk reduction options, particularly those listed in Council Directive 2000/29/EC. Three entry pathways were identified, with plants for planting being the most important and rated as moderately likely. CSVd is recorded in some EU Member States with a limited distribution and is regulated on chrysanthemum; host plants are widely cultivated in greenhouses and outdoors. Therefore, establishment is very likely. Short-distance spread within a crop is likely, whereas short-distance spread between different species is unlikely to moderately likely. For vegetatively propagated species, in the absence of an efficient certification system, long-distance spread is very likely and a major impact would be expected on chrysanthemum, with associated yield and quality losses. However, under the existing certification scheme for chrysanthemum plant propagation material, the probability of spread through infected cuttings is largely reduced and the direct consequences of viroid outbreaks are expected to be minor. Minimal impact is predicted for other ornamental hosts and a minor impact for solanaceous vegetable crops. The indirect effects of CSVd are considered to be limited, with the exception of eradication. Risk reduction options addressing the sanitary status of the propagation material are likely to be the most effective and feasible. These include the current EU measures, as well as a statutory certification system with associated statutory import requirements or, failing that, but potentially less effective, the use of voluntary industry standards. It is difficult to disentangle the benefits of the current legislation from those of the industry-developed chrysanthemum certification system. The high efficacy of current measures is supported by the absence or limited presence of CSVd in the EU and by the limited number of interceptions and findings. Possible improvements to current measures are described and uncertainties discussed.

In 2006, U.S. Department of Agriculture-Animal and Plant Health Inspection Service published a landmark rule providing generic radiation quarantine treatments. The rule approved radiation doses of 150 Gy for any tephritid fruit fly and 400 Gy for all other insects except the pupa and adult stages of Lepidoptera. The generic radiation treatments apply to all fresh horticultural commodities. Therefore, if a pest risk assessment demonstrates that no pupae or adult Lepidoptera are associated with a commodity, export approval can be forthcoming with no further research. Generic treatments are the culmination of decades of research but not an end point. Future research on quarantine and phytosanitary uses of radiation should focus on 1) development of specific doses for quarantine Lepidoptera not covered by the generic treatments, 2) reduction of dose levels for specific pests and commodities to shorten treatment time and minimize any deleterious effects of radiation treatment on commodity quality, 3) development of generic doses below 400 Gy for important groups of quarantine arthropods other than fruit flies, and 4) development of information on commodity tolerance and development of value-added irradiated fresh products that use generic radiation treatments. Generic treatments will facilitate safe trade between countries that have approved phytosanitary uses of radiation for fresh agricultural commodities.

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.

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.

SUMMARY The pinewood nematode (PWN), Bursaphelenchus xylophilus, is a major pathogen of conifers, which impacts on forest health, natural ecosystem stability and international trade. As a consequence, it has been listed as a quarantine organism in Europe. A real-time PCR approach based on TaqMan chemistry was developed to detect this organism. Specific probe and primers were designed based on the sequence of the MspI satellite DNA family previously characterized in the genome of the nematode. The method proved to be specific in tests with target DNA from PWN isolates from worldwide origin. From a practical point of view, detection limit was 1 pg of target DNA or one individual nematode. In addition, PWN genomic DNA or single individuals were positively detected in mixed samples in which B. xylophilius was associated with the closely related non-pathogenic species B. mucronatus, up to the limit of 0.01% or 1% of the mixture, respectively. The real-time PCR assay was also used in conjunction with a simple DNA extraction method to detect PWN directly in artificially infested wood samples. These results demonstrate the potential of this assay to provide rapid, accurate and sensitive molecular identification of the PWN in relation to pest risk assessment in the field and quarantine regulation.

The unmitigated pest risk potential for the importation of unprocessed logs and chips of 18 species of eucalypts (Eucalyptus amygdalina, E. cloeziana, E. delegatensis, E. diversicolor, E. dunnii, E. globulus, E. grandis, E. nitens, E. obliqua, E. ovata, E. pilularis, E. regnans, E. saligna, E. sieberi, E. viminalis, Corymbia calophylla, C. citriodora, and C. maculata) from Australia into the United States was assessed by estimating the likelihood and consequences of introduction of representative insects and pathogens of concern. Twenty-two individual pest risk assessments were prepared, fifteen dealing with insects and seven with pathogens. The selected organisms were representative examples of insects and pathogens found on foliage, on the bark, in the bark, and in the wood of eucalypts. Among the insects and pathogens assessed for logs as the commodity, high risk potentials were assigned to the following 14 organisms or groups of organisms.

Biological control of weeds is still a relatively new field in plant pathology, in which, instead of trying to keep out exotic plant pathogens or to contain indigenous ones, they are actively being exploited in weed management, particularly for alien invasives. Two broad approaches can be distinguished, although these are not necessarily mutually exclusive: classical or inoculative biological control, involving the importation and release of co-evolved, exotic pathogens from the centre of origin of the alien target weed; and, inundative or augmentative control, whereby indigenous pathogens are mass-produced and applied as formulated products (mycoherbicides). This paper attempts to identify and analyse the risks involved using examples from past and present weed-pathogen biocontrol initiatives, with an emphasis on Australian experiences.