Lesson 3: Phytosanitary Systems
Topic 1: Plant Pest ID Systems
Remember that most programs of phytosanitary measures require a network of reliable pest identification resources.
Objectives:
- Recall the necessity of having an authorized process and laboratory system for making definitive pest identifications.
In order for plant health officials to be effective in mitigating pest risks, they must have access to a reliable and efficient system to identify pests. Several common pest risk management strategies, such as pest survey, maintaining pest-free areas, inspections, and issuing phytosanitary certificates, all require a high level of certainty about the identity of the pest and therefore the level of risk it poses. Correct identification is critical because plant health management and policy decisions are based on the identity of a pest.
All successful pest ID systems involve a central laboratory that is authorized to make final pest identifications. Depending on their size and agricultural needs, some larger countries have a tiered set of laboratories that feed into one centralized laboratory. Most countries have a simple, centralized framework where all samples are sent to only one authorized laboratory.
The NPPO should communicate clearly with all pest ID laboratories in its country so that everyone knows exactly where to send suspicious samples for final identification. When the NPPO clearly communicates where to send samples and who has authority to identify pests, it ensures that laboratories can easily trace how the pest was identified and the corresponding decisions stemming from identifications. A reliable system can also prove that a legal authority made the identifications that are guiding regulatory action. It must be clearly communicated to the entire set of stakeholders about where samples should be sent for pest ID. Samples sent to the wrong place can lead to delayed decisions and potentially costly mistakes.
Once at the laboratory, samples will be tested either with the goal to detect pest presence or to identify whether or not something is a pest. A detection test is run to determine if a particular known pest is present. However, this type of test will not reveal what else may be in the sample. These methods are often used for difficult to see plant pests such as bacteria, viruses, or certain types of fungi.
Identification is performed when no specific diagnostic test exists or the pest is unknown. The goal is to put a specific name to a pest found on a sample. In the case of insects, or other pests that are large enough to be seen upon inspection, identification may include comparing morphology of the pest to literature descriptions, taxonomic keys, or specimens from a collection. For pests such as bacteria and viruses, this process may include comparing DNA sequences from the specimen to a database of sequences.
Many factors must be considered when determining whether to run a diagnostic test or perform an identification. The current circumstances, the level of risk or danger the potential pest poses, time constraints, cost, and reliability of the method, should all be considered before selecting a test method. Below is a review of circumstances where each of these methods is commonly used.
Trustworthy laboratories must use reliable sources of pest identification evidence and keep impeccable records. Reliable sources of pest identification evidence and information sources for newly discovered pests are necessary because this evidence is used to defend regulatory and other phytosanitary measure requirements. This data may also be needed for convincing stakeholders of the necessity for an unpopular measure that must be taken to protect the country’s agriculture sector.
There are four general categories of information sources: collector/identifiers, technical identification, location/date, and publication/records. Each category has varying levels of reliability. For example, an expert amateur in the collector/identifier category would not be as reliable for pest identification as a taxonomic specialist. Be sure to carefully consider your sources before making regulatory decisions.
Organized and correct records are also essential to supporting regulatory decisions. Highly organized records instill trust by showing exactly how the identification was made and where the information came from. All of this information must be 100% traceable and readily available to answer questions about how a pest may have been identified. Only perfect record keeping can ensure all steps in the process are complete and can be traced. This is particularly important when the identification could justify unpopular, drastic containment or eradication actions.
What information from an identification needs to be recorded and easily traced?
ISPM 27 lists the following as mandatory for record keeping:
- Scientific name of pest identified
- Code or reference number of the sample (for traceability)
- Nature of infested material (including scientific name of host where applicable)
- Origin (including the geographic location if known) of the infested material and location of interception or detection
- Description of signs or symptoms (including photographs where relevant) or the absence of signs or symptoms
- Methods, including controls, used in the diagnosis, and the results obtained with each method
- Measurements, drawings, or photographs of the diagnostic features (where relevant) and an indication of the developmental stage (for morphological or morphometric methods)
- Documentation of test results, such as photographs of diagnostic gels or ELISA printouts, or results on which the diagnosis was based (for biochemical and molecular methods)
- Magnitude of any infestation, where appropriate (how many individual pests found, how much damaged tissue)
- Name of the laboratory and, where appropriate, the name of the person(s) responsible for and/or who performed the diagnosis
- Dates of collection of the sample and of detection and identification of the pest
- Status of the pest, alive or dead, or viability of its development stages, where appropriate
Remember always that an authorized pest identification framework is the foundation of almost all risk management actions in a plant health protection program. Everything hinges on the proper identification of pests.
For more details on creating and utilizing plant pest identification systems, please review Module 8: Plant Pest ID Systems.
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