Quantitative models have several advantages compared to qualitative methods for pest risk assessments (PRA). Quantitative models do not require the definition of categorical ratings and can be used to compute numerical probabilities of entry and establishment, and to quantify spread and impact. These models are powerful tools, but they include several sources of uncertainty that need to be taken into account by risk assessors and communicated to decision makers. Uncertainty analysis (UA) and sensitivity analysis (SA) are useful for analyzing uncertainty in models used in PRA, and are becoming more popular. However, these techniques should be applied with caution because several factors may influence their results. In this paper, a brief overview of methods of UA and SA are given. As well, a series of practical rules are defined that can be followed by risk assessors to improve the reliability of UA and SA results. These rules are illustrated in a case study based on the infection model of Magarey et al. (2005) where the results of UA and SA are shown to be highly dependent on the assumptions made on the probability distribution of the model inputs.

Zambia is a landlocked developing country in southern Africa. It is an importer and exporter of plants and plant products. These are potential pathways for introducing exotic plant pests that may affect agricultural production and/or limit access to international export markets. In this regard, the National Plant Protection Organization (NPPO) of Zambia is responsible for formulating phytosanitary regulations to ensure risks of introducing exotic plant pests are minimized. For this, the application of Pest Risk Analysis (PRA) is a vital component of any phytosanitary service. PRAs can be data demanding, time consuming and complex. As a consequence, a simplified procedure that aligns Zambia’s national phytosanitary capacity and resources has been developed. The procedure has potential to be applied by other developing countries in similar situations. This simplified procedure focuses on the entry, establishment and spread of pests, the consequences of their introduction, and uses readily available data accessible to the NPPO of Zambia in order to facilitate a quicker response. The procedure developed seeks answers to questions which are phrased as closed questions, i.e. an answer is either ‘yes’ or ‘no’, avoiding relative descriptive answers such as ‘low’, ‘medium’ or ‘high’. | The authors thank the New Zealand Ministry of Foreign Affairs and Trade for awarding a commonwealth scholarship to the senior author to undertake the research described in this paper.

Small hive beetle (SHB) and Tropilaelaps are bee diseases considered exotic in the EU. SHB is a flying coleopteran that can be attracted to the odours of bees and bee products. In addition, SHB can survive and reproduce on a variety of ripe fruits. Tropilaelaps is an ectoparasite that does not survive long without honey bee brood and cannot fly by itself. The methodology used to assess the risk of entry of these pests in this scientific opinion was adapted from a pest risk assessment for entry used in the field of plant health. A qualitative risk assessment was performed taking into account current legislation but excluding the implementation of risk reduction options. This approach allowed the assessment of the worst case scenario for each risk factor. The risk pathways with a high risk of pest entry are ‘import of bee products (use in apiculture)’ for SHB and ‘accidental import of bees’ (unintended presence of bees in a non-bee consignment) for both pests. The other risk pathways are associated with a moderate or low risk of SHB or Tropilaelaps entry into the risk assessment area. Risk reduction options were assessed separately from the risk assessment. Examples of risk reduction options with a high effectiveness and a high technical feasibility are the use of health certificates to guarantee pest freedom of consignments and keeping consignments without honey bee brood. Options with a high effectiveness and technical feasibility were identified in all risk pathways except ‘accidental import of bees’ and ‘dispersal of the pest via natural means and/or flight’. The AHAW Panel identified the need for validated rapid detection methods and for handling and sampling of imported bees in insect-proof environments. Education and training could help to monitor the pest distribution and to prevent pest entry by improving awareness, skills and expertise.

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.

The Panel on Plant Health conducted a pest risk assessment for Puccinia horiana Hennings (the causal agent of chrysanthemum white rust) for the EU territory, identified risk management options and evaluated their effectiveness. The assessment was conducted taking into account current EU legislation. The Panel also provided an opinion on the effectiveness of the present EU requirements against this organism, listed in Council Directive 2000/29/EC. Two major pathways for entry were identified: plant material of susceptible hosts for propagation purposes and cut flowers of Chrysanthemum × morifolium. The probability of further entry of the pest was considered unlikely, as the existing certification schemes for propagation material should reduce the risk of importing infected cuttings. For cut flowers, pest transfer to susceptible hosts is associated with the potentially incorrect disposal of cut flower waste within the vicinity of places of production, which is considered a rare event. The probability of establishment and further spread were both considered very likely. The current overall impact in the risk assessment area was considered minor, with medium uncertainty, mainly because standard protective actions are taken in most EU production areas. Risk reduction options to reduce the probability of entry and spread and mitigate the impact were analysed. Council Directive 2000/29/EC addresses mainly the sanitary status of the propagation material. The Directive cannot prevent the entry, establishment and spread, or mitigate the impact, of the pathogen. Were the current regulation to be removed, the frequency of introduction would probably increase. This poses a risk because, although the pest is widespread in the risk assessment area, not all Member States are infested and not all pest pathotypes are present. If a statutory certification system, with associated import requirements for propagation material of host plants, were introduced, this would include practically all prescriptions of the present regulation.

Pest risk maps illustrate where invasive alien arthropods, molluscs, pathogens, and weeds might become established, spread, and cause harm to natural and agricultural resources within a pest risk area. Such maps can be powerful tools to assist policymakers in matters of international trade, domestic quarantines, biosecurity surveillance, or pest-incursion responses. The International Pest Risk Mapping Workgroup (IPRMW) is a group of ecologists, economists, modellers, and practising risk analysts who are committed to improving the methods used to estimate risks posed by invasive alien species to agricultural and natural resources. The group also strives to improve communication about pest risks to biosecurity, production, and natural-resource-sector stakeholders so that risks can be better managed. The IPRMW previously identified ten activities to improve pest risk assessment procedures, among these were: “improve representations of uncertainty, … expand communications with decision-makers on the interpretation and use of risk maps, … increase international collaboration, … incorporate climate change, … [and] study how human and biological dimensions interact” (Venette et al. 2010).