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EPPO’s regional approach to invasive alien species

Ian M. Smith

Director-General, EPPO, 1 rue Le Nôtre, 75016 Paris, France; e-mail: [email protected]


A longstanding regional plant protection organization with 46 members in 2004, the European and Mediterranean Plant Protection Organization (EPPO) has developed over 400 regional standards for phytosanitary measures. Many refer to a particular standard (PM 1/2) listing two groups of pests recommended for regulation as quarantine pests. EPPO members are encouraged to manage these pests nationally while supporting a harmonized regional approach. In 2002, EPPO Council resolved that invasive alien species affecting plants are quarantine pests. Quarantine pests may include pests of agriculture, of forests and of wild flora, indirect pests of plants, and plants themselves. The latter category is of particular relevance to invasive alien species. EPPO recommends its members take general background measures against alien pests as well as specific measures for individual pests. An expert panel has built up a list of plants reported to be invasive in various EPPO countries. From that list, some 40 species have been selected for more detailed study, including pest risk analysis.


Founded in 1951, the European and Mediterranean Plant Protection Organization is the regional plant protection organization for Europe and the Mediterranean region. It has 46 member countries encompassing all the member states of the European Union (including the EU accession states of 2004) and other future probable EU members, Russia and some other countries of the Commonwealth of Independent States, as well as certain other Mediterranean countries (in North Africa and Near East). EPPO works with the national plant protection organizations of its members, i.e. the authorities responsible for all regulatory aspects of plant protection, and particularly of plant quarantine (whether applied to import at national borders or as official control within the country). The EPPO Secretariat in Paris manages a programme of international work, which produces regional standards recommended to the members. These standards are drafted by panels of experts from the member countries, coordinated by the Working Party on Phytosanitary Regulations. They are then sent out for consultation to the members, and finally approved by the Executive Committee and Council of EPPO.

The regional standards arising from many years of work on phytosanitary measures are classed in the following nine different sets (with the approximate number of standards shown in parentheses):

These numerous standards provide very solid support for the members in EPPO’s long-lasting work on quarantine pests. Many of them refer to one particular general standard: EPPO Standard PM 1/2: A1 and A2 lists of pests recommended for regulation as quarantine pests. This standard exemplifies the general EPPO principle that phytosanitary measures should mainly target individual specified quarantine pests on a case-by-case basis. It also makes a fundamental distinction between the A1 list (of pests that are recognized not to be present in any part of the EPPO region and that present a risk to most or all parts of the region) and the A2 list (of pests with a limited distribution in EPPO region, presenting a risk of further spread).

Members are recommended to manage these pests by national phytosanitary regulations, while respecting a harmonized regional approach. In a large continent with numerous internal borders, it is important that countries’ phytosanitary efforts should be supported by their neighbours. The regulations on these pests are in any case subject to the disciplines of the International Plant Protection Convention and the World Trade Organization. In particular, they have to be technically justified by pest risk analysis. This is ultimately a national responsibility, but EPPO is able, through expert international panels, to make general pest risk analyses for the EPPO region. These provide valuable support for national pest risk analyses.

Quarantine pest concept

Up till now, this system has been applied principally to quarantine pests in relation to agriculture and without any reference to invasive alien species. However, in 2002, EPPO Council made a resolution to the effect that: first, invasive alien species that have an effect on plants are quarantine pests under the IPPC; second, NPPOs should now consider their responsibilities for the management of such species, in cooperation with the environmental authorities. This resolution also has the effect that much of EPPO’s past work is covered by the general invasive alien species concept.

Classically, quarantine pests invade agricultural ecosystems, but the quarantine pest concept can now be applied to:

The case of plants is a particularly important one in relation to invasive alien species. Plants may be quarantine pests as parasites, e.g. Arceuthobium spp. (dwarf mistletoes) and Striga spp. (witchweeds). These cases already feature in the regulations of some EPPO countries. They may also be weeds (of cultivation), usually annual weeds whose seeds may be imported as contaminants of grain or seed lots. Some EPPO countries list quarantine weeds, but up till now pest risk analyses done in the EPPO framework have had difficulty in finding technical justification for this: the weeds are rather widespread and the measures used doubtfully effective. Nevertheless, there is nothing in principle against a weed being a quarantine pest, if it satisfies the criteria. Finally, invasive alien plants (in environments other than cultivated land) constitute, in practice, the major group of invasive alien species having an effect on plants. This is the main area where EPPO expects to extend its activity, but no cases are yet agreed. Some weeds of cultivation may also fall in this category, e.g. Ambrosia artemisiifolia, Acroptilon repens.

EPPO regional approach

EPPO’s intended approach is to treat invasive alien species as quarantine pests. It is expected that invasive alien plants will be the main category under consideration, but others may also arise. Candidate quarantine pests are identified, documented and subjected individually to pest risk analysis following the supplemented text of ISPM 11 [2004]: Pest risk analysis for quarantine pests, including analysis of environmental risks and living modified organisms. In practice, EPPO uses its own regional version of this standard, namely EPPO Standard PM 5/3: Pest risk assessment scheme, arranged in the form of a decision-making scheme with a series of questions. This is being adapted to cover pest plants more effectively. On the basis of the pest risk management section of this analysis, measures are proposed for each invasive plant. The output is in the form of a general recommendation to countries, which will probably distinguish different levels of risk for different parts of the EPPO region. Risks of spread from country to country within the region are also considered.

This recommendation has then to be adopted by consensus by the EPPO members, after appropriate consultation. If it is adopted, the members are under no obligation to follow the recommendation, but there is a general policy of “regional solidarity”. In practice, such recommendations are either rapidly taken up by several major countries, then followed by many others, or else simply ignored. In some cases, the recommendations are useful to only a small group of countries at risk. Since the 1990s, and increasingly in future, the main question is what is decided by the countries of the European Union, because they are under the obligation to take common measures.

If the pest is an invasive plant primarily affecting the environment, the NPPOs will also have to consult with national environmental authorities in evaluating the risk to their territory and the national measures to be taken. As contracting parties to the Convention on Biological Diversity, they should also respect the CBD guiding principles.

EPPO also recommends general background measures against alien pests, not targeting specific pests. Such measures may be relevant for invasive alien plants, for example, measures concerning the import of soil and growing media.

Finally, EPPO publishes on its Web site its “alert list”. This brings to members’ immediate attention any pest incident that could be of phytosanitary significance. Such a listing does not automatically lead to further analysis or regulation, but it may do so. Several invasive plants feature on the alert list.

Origins and pathways

The questions of origin and pathway are not the same for invasive plants as for other quarantine pests. For the A1 case (a pest plant not yet introduced to an area), there may be multiple entry pathways, many more than for a pest associated with a particular host. It may be difficult to evaluate the relative importance of these pathways, apart from the specific case of deliberate import of an ornamental plant. The plants concerned may not be invasive in their country of origin, so it is difficult even to initiate a pest risk analysis. Certainly, there are plants that are well known to be invasive in other continents but not present in Europe. These can readily be targeted, but other cases may be difficult to categorize.

For the A2 case (a pest plant already introduced but not widely distributed and under official control), entry pathways are not usually the key priority. The most important issue is how the plant will spread within the PRA area, which will most often be by natural means. The plant is probably known to be invasive, because that is what draws attention to it in the first place (but it is recognized that some plants become invasive only after a lag phase). The A2 pest plants are thus relatively easy to categorize, but it is difficult to decide appropriate measures.

Application of EPPO regional standards

Many of the EPPO standards for phytosanitary measures are also relevant for invasive plants. They can be included in lists of quarantine pests (PM1) and specific measures for each can be proposed (PM2). Specific phytosanitary procedures (PM3) may be appropriate (e.g. treatments). Pest risk analysis (PM5) has to be adapted to cover pest plants. Detection and identification of pest plants may depend on diagnostic protocols (PM7). Commodity-specific measures (PM8) may need to be extended to cover pest plants. Invasive plants may in particular require national regulatory control systems (PM9), which may constitute the main measure in practice.

Table 1: Invasive plants selected for further study within EPPO.

Terrestrial plants

Aquatic plants

Abutilon theophrasti

Azolla filiculoides

Acer negundo

Crassula helmsii

Acroptilon repens

Egeria densa

Ailanthus altissima

Elodea spp.

Ambrosia artemisiifolia

Eichhornia crassipes

Amelanchier spicata

Hydrocotyle ranunculoides

Bidens frondosa

Lagarosiphon major

Cenchrus incertus

Lemna minuta, L. turionifera

Cyperus esculentus

Ludwigia peploides, L. uruguayensis

Fallopia japonica, F. sachalinensis, F. x bohemica

Myriophyllum aquaticum

Galinsoga ciliata, G. parviflora

Salvinia molesta

Helianthus tuberosus

Heracleum mantegazzianum

Heracleum sosnowskyi

Impatiens glandulifera

Impatiens parviflora

Lupinus polyphyllus

Panicum spp.

Prunus serotina

Rhododendron ponticum

Senecio inaequidens

Solanum elaeagnifolium

Solidago canadensis, S. gigantea

Sorghum halepense

Spartina anglica

EPPO’s future programme

EPPO has already taken specific steps to develop its systems for invasive alien species. It encourages the national plant protection organizations of its members to collect and communicate information on invasive alien species. It encourages them to take part in future in EPPO’s PRA studies on such pests and to consider what measures may be taken. It encourages them to establish links with the environmental authorities of their countries and to consult with them.

EPPO has also developed international activities. A Panel on Invasive Alien Species has been created, which is currently concentrating on invasive plants. It has so far built up a list of hundreds of plants reported to be invasive in individual EPPO countries, and selected from that list about 40 species (table 1) to be studied in detail (this list of candidates will continue to evolve). The selected pests will be documented in more detail and subjected to pest risk analysis (by systems now being adapted and improved). In due course, measures will be proposed. The invasive alien species will then rejoin the main EPPO system for quarantine pests.

EPPO is also establishing contacts with other international bodies (Convention on Biological Diversity, Bern Convention). EPPO already cooperates with CABI in providing information on quarantine pests for CABI’s information systems (Crop Protection Compendium, distribution maps) and intends to continue to do this for invasive plants.

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