Pest risk assessment of Eotetranychus lewisi for the EU territory

Does the Lewis spider mite constitute a threat to agricultural crops in Europe? New data on occurrence, host plants and damage in the invaded areas in Portugal

The Lewis spider mite (LSM), Eotetranychus lewisi, is an important pest of poinsettias (Euphorbia pulcherrima) and agricultural crops worldwide. In Europe it is a quarantine-regulated pest with established outdoor populations in Portugal. We investigated the pest status and host plants of the LSM in Madeira and the Algarve, collecting and inspecting plants and crops. The LSM was mainly found on naturalized poinsettias and castor-bean. Additionally, live mites were collected in very low numbers from plants of vine, cherimoya, mango, papaya, cherry plum, wild tobacco, and bladder vine, in direct contact or close to LSM-infested poinsettias, strongly suggesting these plants would not be breeding hosts. LSM abundance was low and no damage was observed. Mites were absent from strawberry, bramble and citrus, important hosts worldwide. Field surveys were complemented with a citizen-science experiment in outdoor conditions to test whether proximity to mite-infested poinsettias affected subsequent detections on poinsettia, strawberry, or grapevine. After two months of exposure to potentially dispersing LSM individuals and a further two months under controlled conditions to allow the mite to develop, LSM was detected on the three-recipient species but at low infestation rates, with a higher number of infested leaves and abundance on poinsettias, and absence of damages to crops. Overall, we conclude that the primary reservoirs for LSM populations in southwestern Europe are poinsettia and castor-bean plants, and our results suggest that the LSM is not causing damages to crops and may not be as harmful as expected, which can have implications to the current quarantine-regulation of this mite in Europe.

Standard protocols for plant health scientific assessments

In accordance with the EFSA Strategy 2027 outlining the need for fit-for-purpose protocols for EFSA generic scientific assessments, the EFSA Panel on Plant Health (PLH Panel) developed standard protocols to harmonise the problem formulation process and outputs for mandates addressing recurrent scientific questions. Three types of recurring EFSA plant health mandates require generic scientific assessments: (i) pest categorisation; (ii) commodity risk assessment for the purpose of derogation to provisions of the EU plant health law and (iii) quantitative pest risk assessment. The three standard protocols are tailored to the appropriate level of detail and build on the existing guidance documents laying out the methods for conducting risk assessment in the plant health domain. To develop a standard protocol for pest categorisation, the PLH Panel adapted the latest version of the standard template reporting the evidence needs and the assessment questions to conclude whether a pest fulfils the criteria for being considered a potential quarantine pest for the EU. To develop a standard protocol for commodity risk assessment, the PLH Panel adapted the procedure and standard templates used for commodity risk assessment of high risk plants. To develop a standard protocol for quantitative pest risk assessments (qPRA), the Panel reviewed the existing guidance document on qPRA and the qPRAs published by the PLH Panel. The hierarchy of assessment questions and sub-questions used were identified and extracted. Based on this, a hierarchically organised IT-tool was formulated as protocol for the planning and documentation of future qPRAs.

Pest risk assessment of African Leucinodes species for the European Union

Following a request from the European Commission, the EFSA Panel on Plant Health performed a quantitative risk assessment for the EU of African Leucinodes species (Lepidoptera: Crambidae), which are fruit and shoot borers, especially of eggplant type fruit. The assessment focused on (i) potential pathways for entry, (ii) distribution of infested imports within EU, (iii) climatic conditions favouring establishment, (iv) spread and (v) impact. Options for risk reduction are discussed, but their effectiveness was not quantified. Leucinodes spp. are widely distributed across sub-Saharan Africa but are little studied and they could be much more widespread in Africa than reported. Much African literature erroneously reports them as Leucinodes orbonalis which is restricted to Asia. The import of eggplant type fruit from sub-Saharan Africa consists of special fruit types and caters mostly to niche markets in the EU. The main pathway for entry is fruit of Solanum aethiopicum and exotic varieties of eggplant (S. melongena). CLIMEX modelling was used with two possible thresholds of ecoclimatic index (EI) to assess establishment potential. Climates favouring establishment occur mostly in southern Europe, where, based on human population, 14% of the imported produce is distributed across NUTS2 regions where EI ≥ 30; or where 23% of the produce is distributed where EI ≥ 15. Over the next 5 years, an annual median estimate of ~ 8600 fruits, originating from Africa, and infested with African Leucinodes spp. are expected to enter EU NUTS2 regions where EI ≥ 15 (90% CR ~ 570-52,700); this drops to ~ 5200 (90% CR ~ 350-32,100) in NUTS2 regions where EI ≥ 30. Escape of adult moths occurs mostly from consumer waste; considering uncertainties in pathway transfer, such as adult emergence, mate finding and survival of progeny, the annual median probability of a mated female establishing a founder population in NUTS regions where EI ≥ 15 was estimated to be 0.0078 (90% CR 0.00023-0.12125). This equates to a median estimate of one founder population ~ every 128 years (90% CR approximately one every 8-4280 years). Using an EI ≥ 30, the median number of founder populations establishing in the EU annually is 0.0048 (90% CR 0.0001-0.0739), equating to a median estimate of one founder population approximately every 210 years (90% CR approximately one every 14-7020 years). Under climate change for the period 2040-2059, the percent of infested produce going to suitable areas would be increased to 33% for EI ≥ 15 and to 21% for EI ≥ 30. Accordingly, the waiting time until the next founder population would be reduced to median estimates of 89 years for EI ≥ 15 (90% CR ~ 6-2980 years) and 139 years for EI ≥ 30 (90% CR 9-4655 years). If a founder population were to establish, it is estimated to spread at a rate of 0.65-7.0 km per year after a lag phase of 5-92 years. Leucinodes spp. are estimated to reduce eggplant yield by a median value of 4.5% (90% CR 0.67%-13%) if growers take no specific action, or 0.54% (90% CR between 0.13% and 1.9%) if they do take targeted action, matching previous estimates made during a risk assessment of L. orbonalis from Asia.

Pest risk assessment of Leucinodes orbonalis for the European Union

Following a request from the European Commission, the EFSA Panel on Plant Health performed a quantitative risk assessment of Leucinodes orbonalis (Lepidoptera: Crambidae), the eggplant fruit and shoot borer, for the EU. The assessment focused on potential pathways for entry, climatic conditions favouring establishment, spread and impact. Options for risk reduction are discussed but effectiveness was not quantified. L. orbonalis is a key pest of eggplant (aubergine/brinjal) in the Indian subcontinent and occurs throughout most of southern Asia with records mostly from India and Bangladesh. The main pathway of entry is fruit of solanaceous plants, primarily exotic varieties of eggplant, Solanum melongena and turkey berry, S. torvum. The trade in both commodities from Asia is small but nevertheless dwarfs the trade in other Solanum fruits from Asia (S. aethiopicum, S. anguivi, S. virginianum, S. aculeatissimum, S. undatum). Other Solanum fruits were therefore not further assessed as potential pathways. The trade in eggplant from Asia consists of special fruit types and caters mostly to niche markets in the EU, while most eggplant consumed in Europe is produced in southern European and northern African countries, where L. orbonalis does not occur. Using expert knowledge elicitation (EKE) and pathway modelling, the Panel estimated that approximately 3-670 infested fruit (90% certainty range, CR) of S. melongena or fruit bunches of S. torvum enter into regions of the EU that are suitable for L. orbonalis establishment each year. Based on CLIMEX modelling, and using two possible thresholds of ecoclimatic index (EI) to indicate uncertainty in establishment potential, climates favouring establishment occur mostly in southern Europe, where, based on human population, approximately 14% of the imported produce is distributed across NUTS2 regions where EI ≥ 30; or 23% of the produce is distributed where EI ≥ 15. Escape of adult moths occurs mostly from consumer waste. By analysing results of different scenarios for the proportion of S. melongena and S. torvum in the trade, and considering uncertainties in the climatic suitability of southern Europe, adult moth emergence in areas suitable for establishment is expected to vary between 84 individuals per year and one individual per 40 years (based on 90% CR in different scenarios). In the baseline scenario, 25% of the solanaceous fruit from Asia is S. torvum, 75% is S. melongena and EI ≥ 30 is required for establishment. After accounting for the chances of mating, host finding and establishment, the probability of a mated female establishing a founder population in the EU is less than 1 in 100,000 to about 1 event per 622 years (90% CR in baseline scenario). The waiting time until the first establishment is then 622 to more than 100,000 years (CR). If such a founder population were established, the moth is estimated to spread at a rate of 0.65-7.0 km per year after a lag phase of 5-92 years. The impact of the insect on the production of eggplant is estimated to be 0.67%-13% (CR) if growers take no specific action against the insect and 0.13%-1.9% if they do take targeted actions. Tomato (S. lycopersicum) and potato (S. tuberosum) are hosts of L. orbonalis, but the insect does not develop to maturity in tomato fruit, and it does not feed on potato tubers under field conditions; hence, damage to potato can only occur due to feeding on shoots. Tomato and potato are not preferred hosts; nevertheless, impact can occur if populations of L. orbonalis are high and preferred hosts are not available. The Panel did not assess this damage due to insufficient information.

Assessing the probability of freedom from pine wood nematode based on 19 years of surveys

Many quarantine pests, such as the pine wood nematode (PWN, Bursaphelenchus xylophilus), are surveyed annually in all EU countries. Although a lot of resources are spent in the surveys, the confidence in pest freedom achieved with them is not commonly analysed. We assessed the probability that Finland is free from PWN, based on the surveys done in 2000–2018. We used the methods employed in the risk-based estimate of system sensitivity tool (RiBESS), which has recently been recommended for quarantine pest applications. We considered two scenarios: 1) the surveys aimed to justify phytosanitary import requirements and to facilitate exports and 2) the surveys aimed to detect invasions early to enable eradication of outbreaks. These differed only in the pest prevalence that the surveys were expected to detect. The surveys appeared to support the assumption that PWN is not present in Finland, but they did not seem extensive enough to ensure early detection of invasions. The sensitivity of the import-export surveys was greater than 0.6 in 13 years, whereas that of the early detection surveys was always below 0.25. The probability of freedom achieved in 2018 following 19 years of surveys increased asymptotically with the mean time between invasions. For the import-export surveys, this probability was at least 0.95 unless the mean time between invasions was less than 13 years. For the early detection surveys, the probability of freedom was less than 0.73 unless the mean time between invasions was 63 years or more. The results were rather robust with respect to the parameters for which exact information was lacking. To improve the assessment, a quantitative estimate of the probability of PWN invasion to Finland and a thorough assessment of the maximum area of an eradicable infestation would be needed. To gain an understanding about the true impact of quarantine pest surveys on biosecurity, more assessments, like the one presented in this paper, are needed.

Guidance on quantitative pest risk assessment

This Guidance describes a two-phase approach for a fit-for-purpose method for the assessment of plant pest risk in the territory of the EU. Phase one consists of pest categorisation to determine whether the pest has the characteristics of a quarantine pest or those of a regulated non-quarantine pest for the area of the EU. Phase two consists of pest risk assessment, which may be requested by the risk managers following the pest categorisation results. This Guidance provides a template for pest categorisation and describes in detail the use of modelling and expert knowledge elicitation to conduct a pest risk assessment. The Guidance provides support and a framework for assessors to provide quantitative estimates, together with associated uncertainties, regarding the entry, establishment, spread and impact of plant pests in the EU. The Guidance allows the effectiveness of risk reducing options (RROs) to be quantitatively assessed as an integral part of the assessment framework. A list of RROs is provided. A two-tiered approach is proposed for the use of expert knowledge elicitation and modelling. Depending on data and resources available and the needs of risk managers, pest entry, establishment, spread and impact steps may be assessed directly, using weight of evidence and quantitative expert judgement (first tier), or they may be elaborated in substeps using quantitative models (second tier). An example of an application of the first tier approach is provided. Guidance is provided on how to derive models of appropriate complexity to conduct a second tier assessment. Each assessment is operationalised using Monte Carlo simulations that can compare scenarios for relevant factors, e.g. with or without RROs. This document provides guidance on how to compare scenarios to draw conclusions on the magnitude of pest risks and the effectiveness of RROs and on how to communicate assessment results.

Pest risk assessment of Eotetranychus lewisi for the EU territory

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.