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Adaptation of regional pest risk assessment to the revised ISPM 11

Gritta Schrader

Technical University and Plant Health Department of the Federal Biological Research Centre, Messeweg 11/12, 38104, Braunschweig, Germany; e-mail:


The European and Mediterranean Plant Protection Organization (EPPO) provides a scheme to assess the risk of organisms that are harmful to plants. This scheme is designed as a user-friendly questionnaire and has been available since 1997. It is based on the first international standard for phytosanitary measures (ISPM) on pest risk analysis, ISPM 2, and addresses environmental risks of plant pests only generally. Two factors necessitated an adaptation of the EPPO scheme: the development of an international standard on pest risk analysis for quarantine pests (ISPM 11) and its supplement on the analysis of environmental risks; and a new policy of EPPO focusing in more detail on the risks of plant pests to biodiversity and human use. These changes demanded that the scheme be changed to accord with revision of ISPM 11. The paper describes the structure of the EPPO scheme and how it is used. It explains the adaptations of the EPPO scheme to ISPM 11, in particular to environmental aspects, and gives an outlook on how the EPPO scheme can be used.


Under the International Plant Protection Convention pest risk analysis includes assessment of whether a plant pest should be regulated as well as evaluation of options for measures against its introduction and spread. In this context, two IPPC risk analysis standards have been adopted, namely ISPM 2: Guidelines for pest risk analysis in 1996 and ISPM 11 [2001]: Pest risk analysis for quarantine pests, both focusing mainly on the unintentional introduction of plant pests. The evaluation of environmental impacts is already mentioned in these standards. The European and Mediterranean Plant Protection Organization developed a risk assessment scheme in 1997 (EPPO, 1997) and a risk management scheme in 2000 (EPPO, 2000), basing them on the IPPC pest risk analysis.

For a more detailed consideration of effects on biodiversity caused by unintentionally as well as intentionally introduced quarantine pests, a supplement (Analysis of environmental risks) to ISPM 11 was adopted in 2003.[7] It is based on the statements of the Interim Commission on Phytosanitary Measures concerning invasive alien species (FAO, 2001). As a reaction to the activities on invasive alien species in the framework of the IPPC, EPPO started an extensive work programme in 2001. The work programme includes the adaptation of the EPPO PRA schemes to the revised ISPM 11, also taking into consideration criteria of the Convention on Biological Diversity.

Analysis of environmental risks

The supplement to ISPM 11 concerning environmental risks covers preventing the introduction of invasive alien species harmful to plants and selecting adequate control strategies if an introduction could not be prevented. It provides more detailed guidance for analysis of risks of plant pests to the environment and to biological diversity. With the revised ISPM 11, indirect effects on plants or on plant health in ecosystems or habitats can be assessed and managed. In addition, more attention is paid to the precautionary approach.

The revised IPPC standard lists several examples of pest effects on plants, dividing them into direct and indirect consequences. Direct effects include:

Indirect consequences of pest effects on plants include:

The EPPO pest risk assessment scheme

The IPPC standards on pest risk analysis are useful general bases to the assessment of pest risks, containing all relevant and necessary steps and being recognized by the WTO via the SPS Agreement (WTO, 1994). Nevertheless, their applicability can be enhanced when transformed into a questionnaire. EPPO supplies a user-friendly questionnaire (EPPO, 1997) to assess the risks of organisms that are harmful to plants and to apply pest risk analysis in the framework of the IPPC. This scheme provides technical justification for the regulation of certain pests for the EPPO region (or parts of it) as the PRA area. It is based on ISPM 2, addressing environmental risks of plant pests only generally. The structure as well as the use of the EPPO scheme is described below and its adaptation to the revised ISPM 11, in particular to its applicability to plants as pests.

Structure of the EPPO PRA scheme

The (more or less) simple, clearly arranged scheme includes a sequence of questions for deciding whether an organism could present a pest risk and gives detailed instructions for the following stages of pest risk analysis for quarantine pests:

In the initiation stage, the reasons for performing a pest risk analysis have to be given, the identity of the organism has to be indicated and the PRA area (i.e. the region for which the risk posed by the organism is to be assessed) has to be defined.

Then follows a qualitative assessment, to determine if the organism could be a pest and present a risk in the PRA area (section A). Geographical and regulatory criteria have to be considered. An estimation is made of whether the organism would be able to establish in the PRA area and whether there is potential for economic, environmental and social damage. If the organism does not fulfil certain criteria, the assessment can be terminated.

If the organism is deemed to present a possible risk to or in the PRA area, a quantitative assessment is made (section B), with an in-depth analysis of its probability of introduction and spread and a more detailed economic impact assessment. This is evaluated with the help of a series of questions, for example:

Replies to section B are expressed as scores (1 to 9). It is recommended that a preliminary consideration of questions be conducted to allow a quick decision on whether there is a very obvious risk or no risk at all. If a quick decision is not possible, a full assessment has to be done.

For a pest risk analysis, collection of adequate information is essential. This information is to be interpreted by the risk assessor. To facilitate the collection of data, EPPO provides a checklist (EPPO, 1998), which lists the necessary information that should be considered before deciding if a particular organism qualifies to be declared a quarantine pest. References should be noted for all items of information.

In the final evaluation, a comment of the assessor is requested to indicate (important) uncertainties and to estimate the level of risk. The theoretical pest risk is the introduction potential of the pest combined with potential economic (including environmental and social) impacts. However, the scheme is not designed to provide estimates of meaningful units and it does not include a procedure for the calculation of units. Instead, expert judgement to estimate pest risk is essential. To make the pest risk analysis as transparent as possible and also to allow for any future re-evaluation of the pest risk analysis, all steps of the procedure have to be fully documented, indicating who performed the evaluation, how each decision was reached, the date on which the information was collected and on what information it was based.

Adaptations to the revised ISPM 11

The development of the revised standard including assessment of environmental risks, together with the new policy of EPPO focusing in more detail on risks of plant pests to biodiversity and human use (see also chapter 4), necessitated the revision of the EPPO PRA scheme. This process has been started. The revised scheme will also be applicable to pest plants (invasive plants or weeds) and to indirect plant pests (pests that have negative impacts on other organisms resulting in harm to plants) and will be in line with the IPPC standards.

The most important changes are an adjustment to accord with the sections of ISPM 11 and a rearrangement of questions to follow it more closely. In section A (pest categorization), additional questions are under consideration to cover more precisely the cases of plants as pests (see below). The current scheme does not refer to habitats but to host plants (e.g. How extensive are the host plants in the PRA area?). The revision of the scheme will consider habitats as well.

To make the EPPO scheme easier to apply, questions of the scheme are simplified and questions not relevant to plants are indicated. The scoring system (scores from 1 to 9) will possibly be replaced by words and be reduced to five levels (e.g. very unlikely, unlikely, possible, likely, very likely). To shorten the PRA process, a pest may immediately be declared a (potential) invasive alien species or a quarantine pest if an answer to a critical question (e.g. How important is environmental damage likely to be in the PRA area?) indicates a high impact. The following questions can then be left out. A computerized system planned to run the scheme will avoid going through questions that are not relevant.

The revision is still in process and further discussions in panels are necessary. An EPPO workshop in October 2004 reviewed work on adaptation of the scheme, which is now expected to be finalized in mid-2005.

Applicability of the EPPO scheme to plants as pests

The most important changes regarding environmental aspects are up to now the PRA scheme’s applicability to plants as pests. Invasive plants have effects on the environment; impacts are generally described in qualitative rather than in economic terms. This will be reflected in the revision of the scheme, for example by the following question:

How important is environmental harm caused by the pest within its existing geographic range? (specify)

Note: effects of pests may include: reduction of keystone species; reduction of species that are major components of ecosystems, and of endangered species; significant reduction, displacement or elimination of other native species; indirect effects on plant communities (species richness, biodiversity); significant effects on designated environmentally sensitive areas; significant change in ecological processes and the structure, stability or processes of an ecosystem (including further effects on plant species).

It will be possible to assess not only the unintentional introduction of, for example, seeds or other propagules contaminating imported commodities, but also the intentional import for agriculture or forestry or for horticultural and ornamental purposes. In instances of intentional introduction of plants, the entry of the plant is not part of the assessment. Instead, it is very important to consider the pathway(s) from the garden, field, park, pond or whatever may be the intended habitat for the plant to the unintended habitat where the plant is not wanted. The plant’s establishment in the intended habitat is very likely and, indeed, often promoted. Its establishment in an unintended habitat, however, can cause severe problems. Therefore, its potential for establishment in the unintended habitat has to be assessed. To evaluate the potential invasiveness of a plant is a difficult task. Intrinsic characteristics of invasiveness should be identified as far as possible. This will be covered by the following question:

Does the plant have intrinsic attributes that indicate that it could cause significant harm to plants or plant communities?

It is intended to enclose an annex to the scheme, listing information on intrinsic attributes for invasiveness. For example, a very strong hint for invasiveness is given when a plant is already invasive elsewhere. High propagule pressure, effective reproduction strategies, rapid growth and a broad ecological amplitude are also factors for increased invasiveness.

Principle 10 of the CBD guiding principles on invasive alien species (CBD, 2002; refer also footnote on page 7) recommends that no intentional first-time introduction of an alien species should take place without prior authorization from a competent authority of the recipient state(s). Hence, a pest risk analysis could technically justify import prohibitions of invasive alien plants or special requirements for import or use.

Outlook and conclusions

Pest risk analysis is an essential tool in preventing the introduction and spread of invasive alien species. For all organisms threatening plants or plant products, directly or indirectly, the revised ISPM 11 provides the necessary elements for a substantial risk analysis. The applicability of the standards can be enhanced by transforming the different steps of the assessment into a questionnaire or scheme, as developed by EPPO. After its revision, the EPPO PRA scheme will also be applicable to the assessment of risks posed by the intentional introduction of alien organisms such as ornamental plants. It will be valid as a basis for the justification of an authorization procedure regarding the intentional introduction of organisms with potential impacts on plants. Also, the assessment of risks posed by indirect pests and the resulting consequences will be covered by the revision. With the inclusion of a detailed assessment of environmental risks posed by organisms harmful to plants, the application of the revised EPPO scheme will contribute practically and effectively to the implementation of the CBD guiding principles on invasive alien species.

States should follow the revised IPPC PRA standard and are encouraged to make use of the adapted EPPO PRA scheme for their purposes.


CBD. 2002. Sixth Conference of the Parties, The Hague, the Netherlands, 7-19 April 2002: Decision VI/23: Alien species that threaten ecosystems, habitats or species to which is annexed Guiding principles for the prevention, introduction and mitigation of impacts of alien species that threaten ecosystems, habitats or species (available at

EPPO. 1997. Pest risk analysis: pest risk assessment scheme. EPPO standard PM 5/3(1) (available at

EPPO. 1998. Pest risk analysis: check-list of information required for pest risk analysis (PRA). EPPO standard PM 5/1(1) (available at

EPPO. 2000. Pest risk analysis: pest risk management scheme. EPPO standard PM 5/4(1) (available at

FAO. 2001. Report of the Third Interim Commission on Phytosanitary Measures, Rome, Italy, 2-6 April 2001, Appendix XIII: Statements of the ICPM Exploratory Open-ended Working Group on Phytosanitary Aspects of GMOs, Biosafety and Invasive Species (available at

WTO. 1994. Agreement on the application of sanitary and phytosanitary measures. In: Agreement establishing the World Trade Organization: Annex 1A: Multilateral agreements on trade in goods. Geneva, Switzerland (available at

[7] Note: the supplement to ISPM 11 was published in 2003 as ISPM 11 rev. 1: Pest risk analysis for quarantine pests including analysis of environmental risks. This has subsequently been further supplemented and integrated. The relevant standard is now ISPM 11 [2004]: Pest risk analysis for quarantine pests, including analysis of environmental risks and living modified organisms. The 2003 standard referred to in this paper is described here as the revised ISPM 11. (All adopted ISPMs are available at

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