• Home
• Lessons
  • 1. Review of PRA and Introduction to Risk Assessment
  • 2. Resources Used to Conduct Pest Risk Assessment
  • 3. Conducting Pest Risk Assessment for Trade
  • 4. Practice
  • 5. Module Conclusion
• Topics
  • 1. Initiation
  • 2. Pest Categorization
  • 3. Estimating Likelihood of Introduction
  • 4. Estimating Potential Consequences of Introduction
  • 5. Developing Conclusions and Describing Uncertainty
  • 6. Lesson Summary
• Resources
  • Help
  • Glossary
  • Documents and Videos
  • Acknowledgements

Lesson 3: Conducting Pest Risk Assessment for Trade

Topic 1: Initiation

Why Initiate a PRA?

PRA begins with the initiation stage. PRAs are initiated for many different reasons.

1. Trading partner makes a request to export a particular commodity to an importing country
2. Particular organism has been introduced into an area, or could be introduced, and has been identified as a potential pest
3. Policy changes (laws)
4. Changes in operational approaches (reallocation of resources for surveillance or change in port of entry inspections)
5. Phytosanitary status change for the country

The Initiation Stage

The initiation stage is Stage 1 of PRA, according to the IPPC. At the initiation stage, the analyst

1. Determines whether or not an organism is a pest
2. Defines the PRA area
3. Determines the scope of the assessment

Let us look at each of these activities next.

Determining if the Organism is a Pest

The first step of any risk assessment involves identifying the adverse event, or the bad thing that we are concerned will happen, and the potential hazards that can cause the adverse event. In the case pest risk assessment, the adverse event we are concerned with is the introduction and spread of pests that have the potential to cause damage to our country’s agricultural and natural resources.

In the initiation stage, the analyst determines the identity of the organism(s) of concern. The analyst determines the organism’s taxonomic status. He or she also determines the characteristics that indicate the organism is a plant pest, including the organism’s feeding habits, its ability to be a vector, and any other types of effects it might have on plant health.

The most common taxonomic level that is considered for a pest is species; however, taxonomic groups below species level (e.g., biotypes or strains) or above species level (e.g., genus level) may be considered if evidence suggests such an approach is necessary and technically justified. For instance, many pathogens have different strains or pathovars that are more or less virulent. Some species of whiteflies, for example, have different biotypes that exhibit differing levels of resistance to insecticides.

Defining the PRA Area

Defining the PRA area involves describing the area for which the risk assessment will be applied. The description should focus on the ability of the pest to enter, establish, and spread in that area. Recall that the PRA area is the area for which the PRA is conducted, while the endangered area is the area in which the pest may become established. In either case, however, the area in question may apply to one country, several countries, or a part of a country. Providing maps in this part of the assessment can be useful to make clear exactly what area(s) is under consideration in the assessment.

Determining the Scope

The scope describes the concern or issue the assessment covers, the purpose of the pest risk assessment, and the relevant background or expectations with regard to the assessment. The scope should be described as specifically as possible, because it will define and drive all of the subsequent steps of the assessment.

For instance, a request may be made to examine the risks associated with the importation of Citrus spp. In this case, the analyst can specify that the scope of the assessment applies only to Citrus spp. fruit, a specific species of Citrus, or Citrus plants. Each one of those analyses would result in very different pest profiles and different levels of risk. Thus, a well-defined scope provides focus to the analyst and sets the stage for a pest risk assessment that meets the needs of its audience.

Possible Further Steps

In the case of a pathway risk analysis (such as for a commodity import), the analyst would also identify and describe the relevant pathway(s) and list those pests that are likely to be associated with the pathway(s). The pest risk assessment may then be composed of the combined assessments for each pest associated with the pathway.

Documentation

The analyst should clearly document all of the information from the initiation stage as part of the overall pest risk assessment, including whether any previous relevant assessments have been conducted.

Types of Pests Encountered

Note that a variety of types of organisms may come under consideration in the initiation stage. In addition to organisms traditionally understood to be pests (for example, fruit flies), organisms not traditionally viewed as pests may be examined in Stage 1. They include:

• Biological control and other beneficial organisms
• Plants that are pests (e.g., weeds)
• Living modified organisms and invasive alien species
• Organisms new to science
• Organisms imported for research and other similar purposes

Case Study Exercise

Let’s return to the fictional case of the tamola growers you began examining in Lesson 2. You have already identified the potential hazard, a pest called Pestis horribilis, which is causing serious damage in Exportland but is not currently in Importland.

In Lesson 2, you explored the best available information on Pestis horribilis. The next step is to determine whether or not it fits the definition of a pest. The IPPC defines pest as “any species, strain or biotype of plant, animal or pathogenic agent injurious to plants or plant products” [FAO, 1990; revised FAO, 1995; IPPC, 1997].

Can you answer yes to any of these predictive questions after you reviewed the available information on Pestis horribilis?

• Does the organism have a history of successful establishment in new areas?
• Does the organism have phytopathogenic characteristics?
• Does the organism have phytophagous characteristics?
• Is the organism seen at the time of injury to plants?
• Does the organism belong to a higher taxonomic level (family or genus) commonly containing pests?
• Is the organism capable of acting as a vector for known pests?
• Does the organism harm nontarget beneficial organisms such as pollinators or predators of plant pests?
• Has the organism been documented as a pest in other PRAs or other resources?

Pestis horribilis fits the definition of pest. It has phytophagous characteristics and is observed at the time of severe injury to tamola plants, resulting in decreased harvest yield.

PRA Area Identification

Watch the following video to learn more about identifying a PRA area.

To continue, select Topic 2 from the Topics menu above or click here.