Lesson 3: Types of Pest Risk Analyses

Topic 2: Organism PRA

Organism PRAs are analyses conducted on a single organism. An organism PRA may be done for organisms that are not yet present in a country or organisms that have already been introduced. Not all of these organisms are known pests. Recall that organism PRA can be useful to evaluate the risks of importing beneficial organisms. In this topic, you will learn about the two main applications for organism PRA and the scope of these analyses.

Objectives:

  • Explain how organism PRAs can be used to develop measures for pests that are not yet present in an area or country
  • Explain how organism PRAs can be used to target pest species that have already been introduced to an area or country
  • List some questions that are typically analyzed in an organism PRA
What is an Organism or Pest-specific PRA?

Organism PRAs usually focus on a single species, for example, a species of fruit fly, pathogenic bacteria, or weed. However, they sometimes are used to analyze an entire group of organisms, such as bark beetles or Phytophthora spp. fungi. Organism PRAs may also be conducted when analysing the risk of importing beneficial organisms.

PRAs for New Pests

In most instances, a pest-specific PRA targets organisms that are not yet present in the PRA area (i.e., a quarantine pest). In this case, the PRA is used to determine

  1. Whether the pest is likely to be introduced into the PRA area
  2. The likely consequences if the pest is introduced
  3. Appropriate actions to prevent the pest’s entry, if necessary

In some cases, the organism may be considered an “imminent” threat. For example, a pest that does not occur in a country but that is regularly intercepted in imports into that country is considered an imminent threat. A new pest found in a neighbouring country would also be considered an imminent threat. In these situations, the organism PRA is considered to be urgent since the likelihood of introduction, and therefore the risk, is perceived to be high.

PRAs for Previously Introduced Pests

An organism PRA may also target organisms that have already been introduced into an area, either intentionally or unintentionally. An example of intentional introduction is beneficial organisms. An unintentional introduction might be a new pest species. Once a pest is established in a country, a PRA can be used to determine whether to take measures to control or eradicate that pest. The PRA may also be used to estimate how likely it is that those measures will be successful.

Scope of an Organism PRA

The scope of an organism PRA is determined by the purpose or objective of the PRA. When an organism PRA is conducted for an individual species, the scope is usually well defined. The analysis typically answers questions like:

  • How likely is the pest to enter into a new area?
  • What pathway(s) is the pest likely to follow leading to its introduction to a new area?
  • How likely is the pest to establish in the new area?
  • What pathway(s) is the pest likely to follow after its introduction to a new area (that is, can the pest spread after it is introduced)?
  • What types of impacts can be expected?
  • What is the potential magnitude of the consequences?
  • What measures can be applied to prevent introduction or to control or manage the pest if it is introduced?
  • How feasible are the measures?
  • How cost-effective are the measures?

A well-known model for organism-level PRAs was developed by the European and Mediterranean Plant Protection Organization as the EPPO PRA Decision Support Scheme for Quarantine Pests (EPPO, 2007). This resource is available online at http://archives.eppo.int/EPPOStandards/pra.htm

Organism PRAs are analyses conducted on specific species. An organism PRA may be done for organisms that are not yet present in a country to determine whether a pest is likely to be introduced into a country and, if it is, the likely consequences. Organism PRAs may also be done on organisms that have already been introduced, either intentionally (e.g., beneficial organisms) or unintentionally (e.g., a new pest species). The scope of organism PRAs, as with all PRAs, is determined primarily by the purpose of the PRA.

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