Erroneous host identification frustrates systematics and delays implementation of biological control

Misidentifications of pests and their natural enemies and misinterpretations of pest-natural enemy associations have led to the failure of a number of biological control projects. In addition to misidentification, more complicated kinds of errors, such as mistakes in establishing host records of parasitoids, have resulted in inaccurate host-parasitoid lists of even well-known pest species. Here we discuss a particular problem of misinterpretation caused by complicated host-natural enemy habitats. Six examples are presented illustrating that mistakes in collection of host material can easily result in attribution of natural enemies to a wrong host species. To prevent such mistakes, it is advised that (1) extreme care should be taken when collecting host material in the field, (2) collected material should be partly dissected in order to check for potential contamination with non-host material, (3) supposedly new parasitoid-host associations inferred from specimens that emerged in the laboratory should be confirmed by field observations, (4) assignment of parasitoids to new hosts should only be done after consulting taxonomic specialists for the host and parasitoid

Scientific Opinion on the assessment of the potential establishment of the apple snail in the EU

EFSA requested the PLH Panel to review the current state of the art of the biology and ecology of apple snails, reported in this opinion, and to perform an environmental risk assessment for validation of the Plant Health environment guidance document, which will be provided in a second opinion. The Panel presents in this opinion the current state of the art of the biology of apple snails, and develops and uses a population dynamics model to assess the potential establishment of apple snails in the EU. A thorough review of the literature on the biology of Pomacea canaliculata and P. maculata was performed to collect information and data on life history characteristics related to temperature, which was used in the population dynamics model. Although uncertainties on the systematics and taxonomy of the genus Pomacea remain, it is now acknowledged that Pomacea insularum is a synonym of P. maculata and can be undoubtedly differentiated from P. canaliculata. Natural spread occurs via rivers and canals, in which the snails crawl, drift, float and raft. Flooding increases spread. In addition, attachment to animals (e.g. birds, cattle, horses, deer and aquatic invertebrates) results in spread. Human assistance results in spread through cultivation transport of rice seedlings, aquaculture, aquaria, boats, and agricultural field machinery. The potential distribution of P. canaliculata in Europe was obtained by calculating with the population dynamics model, the average snail abundance per year in each node of a grid of 0.25 × 0.25 degrees covering Europe, which resulted in the following conclusions: (1) the area of potential establishment comprises wetlands of southern Europe (i.e. Spain, southern France, most of Italy and Greece) and the Balkans up to the latitude of the Danube river, (2) the potential area of establishment includes the rice production areas in Europe

Scientific Opinion on the risk to plant health posed by Strawberry crinkle virus to the EU territory with the identification and evaluation of risk reduction options

The Panel on Plant Health assessed the risk to plant health of Strawberry crinkle virus (SCV) for the European Union (EU) territory, and evaluated the current EU legislation and possible risk reduction options. This virus is widely distributed both within and outside Europe and the same applies to its main vector, the strawberry aphid, Chaetosiphon fragaefolii. At-risk hosts (Fragaria spp.) occur widely in Europe. Plants for planting were identified as the most significant entry pathway and the probability of entry is rated as unlikely to moderately likely with high uncertainty. The probability of establishment is rated as very likely with low uncertainty. The probability of local spread by natural means is moderately likely, with high uncertainty, whereas that of human-assisted long-distance spread is unlikely, with medium uncertainty. The potential consequences are rated as minimal to minor with medium uncertainty. Prohibition and restricting import or intra-EU trade to certified materials or to materials originating from pest-free areas or pest-free places of production are the options with highest effectiveness against the risks of introduction or against the risks of further spread. Prohibition and certification are also among the options of high or very high feasibility. In addition, it should be noted that the combination of options (cultural practices, certification, exclusion conditions, tolerant varieties) has an overall high to very high level of effectiveness and feasibility. The current legislation has few weaknesses: the reliance on visual inspection, as well as the exceptions or derogations offered to some countries in which SCV is present. If the current legislation were removed, no major consequences would be expected unless the industry simultaneously ceased its widely adopted certification activity, which seems unlikely given the potential consequence

Scientific Opinion on the pest categorisation of Clavibacter michiganensis subsp. michiganensis (Smith) Davis et al.

The European Commission requested the EFSA Panel on Plant Health to perform the pest categorisation for Clavibacter michiganensis subsp. michiganensis (Cmm). The agent responsible for vascular tomato wilt and canker is the clearly defined and valid gram-positive taxon C. michiganensis subsp. michiganensis. This pathogen can be accurately identified based on a range of sensitive and specific methods. Tomato (Solanum lycopersicum) is the main host, but peppers (Capsicum annum and C. frutescens) are also naturally susceptible to Cmm. These host plants are cultivated throughout Europe and conditions are conducive to disease development in open fields in southern Europe and in greenhouses. The disease is present in many EU Member States. Outbreaks are rare but usually severe. It causes a range of symptoms on the aerial parts of plants, including the fruits. Detection methods are available for any type of plant material either presenting symptoms or symptomless. Seed testing has proven to be a good control option by discarding contaminated seed lots. Despite tomato seed production being done under strict sanitation using recommended practices, seed contamination still occurs occasionally. Contaminated seeds and transplants are responsible for long-distance dissemination of the pathogen. Under conducive conditions, even low levels of seed contamination can result in disease outbreaks. Cultivation practices can favour secondary spread of the bacterium and an increase in disease incidence both in greenhouse and in open-field crops. No effective biological or chemical control agents are registered for bacterial canker in Europe. Cmm meets all criteria defined in International Standard for Phytosanitary Measures (ISPM) 21. Cmm meets all ISPM 11 criteria, although it has been observed in 16 EU Member States. The outbreaks are usually severe but sporadic

Scientific Opinion on the risk to plant health posed by <em>Eutetranychus orientalis</em> Klein in the EU territory, with the identification and evaluation of risk reduction options

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

Scientific Opinion on the risks to plant health posed by Phytophthora fragariae Hickman var. fragariae in the EU territory, with the identification and evaluation of risk reduction options

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

Scientific Opinion on the risks to plant health posed by Bemisia tabaci species complex and viruses it transmits for the EU territory

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, 201

Scientific Opinion on comments provided by Portugal on the phytosanitary risk associated with Pinus pinea for the spread of pine wood nematode

Following a request from European Commission, the PLH Panel examined the comments of the Portuguese plant health authorities on a previous EFSA opinion with regard to pine wood nematode (PWN) and Pinus pinea and a report on PWN surveys in Portugal. Regarding the comment, based on behavioural responses of PWN to CO2 and to ß-myrcene, that Monochamus galloprovincialis can feed on P. pinea without implying PWN infestation, the Panel noted the uncertainties on how chemical attraction influences the exit of PWN from the vector. The Panel agreed that P. pinea is not a preferred breeding host of M. galloprovincialis, but it noted the evidence from Italy of breeding of M. galloprovincialis in fallen woods of P. pinea, suggesting P. pinea to be an occasional host. The Panel agreed that, although pathogenicity of PWN has been recorded on P. pinea in inoculation experiments on small plants, this does not necessarily relate to pathogenicity on larger trees in the field. The additional information on Portuguese PWN surveys is not sufficient to conclude that P. pinea is resistant to PWN. The Panel also noted that asymptomatic infestations by PWN are well known in other areas, and pine species considered tolerant to PWN could still maintain it at low levels in restricted parts of a tree. The Panel concluded that there is high uncertainty concerning the classification of the risk of spread of PWN with plants and wood of P. pinea, owing to the scarcity of information on the interaction of M. galloprovincialis, PWN and P. pinea, as well as on the field resistance of P. pinea to PWN. Owing to high uncertainty related to the host potential of P. pinea, more studies on the transmission of PWN at feeding wounds and on its survival in trees and wood of P. pinea are needed

Scientific Opinion on the risk of Phyllosticta citricarpa (Guignardia citricarpa) for the EU territory with identification and evaluation of risk reduction options

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

Scientific Opinion on the risk to plant health posed by Parasaissetia nigra (Nietner) in the EU territory, with the identification and evaluation of risk reduction options

The Panel on Plant Health conducted a pest risk assessment for Parasaissetia nigra in the European Union (EU) and identified and evaluated the phytosanitary measures listed in Council Directive 2000/29/EC. Entry through the principal pathways is assessed as moderately likely for plants for planting and very unlikely for living parts of plants, such as fruit and cut flowers with foliage, the discrepancy being mainly due to the difference in probability of transfer to a suitable host. Establishment is rated as very likely outdoors in Mediterranean areas and indoors in the whole risk assessment area (where the pest has been present for a long time), and unlikely outdoors in non‐Mediterranean areas. Spread within the EU is considered to be moderately likely because the pest can readily be moved with plant material but is limited by climatic conditions. The magnitude of the potential consequences is rated as minor. The Panel evaluated the effectiveness of current EU phytosanitary measures and concluded that the removal of P. nigra from Annex IIAII would not affect its probability of entry, because the importation from Third countries of some host plants regulated for P. nigra (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 only a very small proportion of the potential host plants of P. nigra,the current phytosanitary measures are mostly ineffective in preventing the further introduction and spread of P. nigra 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 in combination