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RMD-14-03: Deregulation of Yponomeuta malinellus (apple ermine moth)

August 21, 2014


As described by the International Plant Protection Convention (IPPC), Pest Risk Analysis (PRA) includes three stages: initiation, pest risk assessment and pest risk management. Initiating the PRA process involves identifying pests and pathways of concern and defining the PRA area. Pest risk assessment provides the scientific basis for the overall management of risk. Pest risk management is the process of identifying and evaluating potential mitigation measures which may be applied to reduce the identified pest risk to acceptable levels and selecting appropriate measures.

This Risk Management Document (RMD) includes a summary of the findings of a pest risk assessment and records the pest risk management process for the identified issue. It is consistent with the principles, terminology and guidelines provided in the IPPC standards for pest risk analysis which may be found at the International Plant Protection Convention website.

Table of Contents

Executive Summary

Yponomeuta malinellus (apple ermine moth, AEM) has been present in British Columbia (B.C.) and the United States Pacific Northwest states of Oregon and Washington since the early 1980's. Domestic and import requirements have been applied since 1988 to limit the spread of this pest in Canada.

The most recent Canadian Food Inspection Agency (CFIA) pest risk assessment (2009) demonstrated that Y. malinellus populations throughout temperate regions of the world where apple (Malus spp.) is grown are low and below economic thresholds. Based on this updated information, Y. malinellus is no longer considered a pest of economic importance and therefore no longer meets the International Plant Protection Convention (IPPC) definition of a quarantine pest.

After consultation and due consideration of stakeholder comments, the CFIA is deregulating Y. malinellus in Canada and communicating the decision through this Risk Management Document.

1.0 Purpose

The purpose of this document is to inform stakeholders and to record a risk management decision regarding the deregulation of Yponomeuta malinellus (apple ermine moth, AEM).

2.0 Scope

This pest Risk Management Document pertains to Canada's regulations and policies (plant import and domestic movement) with respect to Yponomeuta malinellus.

Information pertaining to current import requirements for specific plants or plant products may be obtained from the CFIA Automated Import Reference System.

3.0 Definitions

Definitions for terms used in the present document can be found in the Plant Health Glossary of Terms.

4.0 Background

Yponomeuta malinellus was reported in British Columbia (B.C.) on Vancouver Island (1981), in the Fraser Valley (1989), and in the Okanagan Valley and Similkameen Valley (1994). In the United States (U.S.), Y. malinellus was found in Washington and Oregon in 1985. It is currently found at low density in Washington, Oregon and B.C.

At the time that Y. malinellus was first reported in B.C., it was considered to have the potential to be a serious pest of Malus spp. Since that time, reports from both the coastal and interior regions of B.C. indicate that its occurrence and impacts have been minimal. In commercial orchards, pest management practices used to control other apple pests have proven to maintain Y. malinellus populations below economically damaging levels.

Yponomeuta malinellus is currently considered to be absent from Eastern Canada. Since 1988, Y. malinellus has been considered a quarantine pest in Canada and domestic and import requirements are applied to limit the spread of this pest. In contrast, the U.S. does not regulate Y. malinellus. It has not established outside the states of Washington and Oregon since it was detected 29 years ago, despite the lack of domestic controls to prevent the movement of this pest.

In 2001, a consultation conducted by CFIA indicated that even though deregulation of Y. malinellus was supported by many stakeholders, not all stakeholders supported the proposal. In 2009, the pest risk assessment for this insect was revised. New evidence indicated that the overall risk attributed to Y. malinellus could be reduced from medium to low. This suggested that this pest should no longer be subject to regulatory requirements because it no longer satisfies the definition of a quarantine pest under the International Plant Protection Convention (IPPC). In July 2012, the CFIA initiated a new consultation to seek stakeholder input on a proposal to deregulate Y. malinellus. Comments received were considered in the decision making process and are reflected in this document.

5.0 Pest Risk Assessment Summary

A pest risk assessment (PRA 98-48) for Y. malinellus was completed in 1998 and updated in 2009 (Dobesberger and Garland, 2009). An update was required to re-evaluate the risk associated with this pest according to new available scientific literature and current observation on the status and impact of this pest in North America. The revised pest risk assessment indicates that the likelihood and the consequence of introduction into all regions of Canada are rated medium and low, respectively, resulting in an overall risk rating of low.

5.1 Pest Biology

5.1.1 Life History

Yponomeuta malinellus is known to have one generation per year. Moths are present from June/July to September (Cossentine and Kuhlmann, 2000, 2001). Females feed on nectar for about a week as they become sexually mature, mate in the tree crown, and lay eggs in masses on young branches in the crown of the host trees (Carter, 1984). An average of 60 eggs/mass (14 to 81 eggs/mass) is laid on the bark of young shoots (Carter, 1984; Kuhlmann et al., 1998). Larvae hatch in early autumn after about 2 weeks, and these larvae overwinter under the protective covering of the egg mass (hibernacula; Humble and Humphreys, 1989; Kuhlmann et al., 1998). In the spring, larvae emerge and begin to mine newly developing leaves in the vicinity. As larvae grow and develop, they feed on leaves within a communal silken tent on shoots (Carter, 1984; Kuhlmann et al., 1998). Mature larvae spin white cocoons that are suspended by silk in rows or clusters along tented shoots. Pupal development lasts from 10 to 14 days after which new adults emerge.

5.1.2 Host Range

The major host of Y. malinellus are species of apple (Malus spp.). It also has been occasionally reported on Pyrus spp.

5.1.3 Distribution

Yponomeuta malinellus is widely distributed throughout temperate areas of the world (Carter, 1984). This includes Europe to the Mediterranean region, North Africa, Asia, and the Pacific Northwest of North America (Zhang 1994). In North America, Y. malinellus is found at low population levels in Oregon, Washington and B.C. (Cossentine and Kuhlmann, 2000, 2001). A single detection on an apple tree in Ontario in 1957 was confirmed eradicated (Parker and Schmidt, 1985).

5.2 Pathways

The only viable human-assisted pathway is the movement of dormant Malus spp. nursery stock. Young larvae overwinter under the protective covering of the egg mass laid on young shoots of host trees, mainly Malus spp. (Unruh et al., 1993). Egg masses are difficult to detect. It has long been known that they may be transported in this manner from one country to another on dormant nursery stock (Hewitt, 1917).

5.2.1 Entry Potential

The population level of Y. malinellus throughout temperate regions of the world where apple (Malus spp.) is grown is generally low and below economic thresholds. The risk of entry via imported dormant nursery stock is reduced because of low pest population levels at source. Yponomeuta malinellus detection requires detailed visual inspection as egg masses are difficult to detect. The potential of entry of Y. malinellus on Malus spp. nursery stock is rated as medium.

5.2.2 Establishment Potential

Apple is cultivated across southern Canada as an ornamental and commercially for its fruit in British Columbia, Ontario, Quebec, Nova Scotia, New Brunswick and Prince Edward Island. Climate modelling indicates that Y. malinellus could establish in southern Ontario and Nova Scotia and is less likely to establish in Quebec. The potential of establishment is rated high.

5.2.3 Spread Potential

Natural spread of Y. malinellus is slow because adults are weak fliers, and flight is local only. The potential of natural spread is rated low.

5.3 Potential Economic and Environmental Consequences

Yponomeuta malinellus is not considered to be a significant pest of apples in North America and Eurasia (Kuhlmann et al., 1998). In B.C., industry specialists describe Y. malinellus as a pest of very low or no concern in both nursery and orchards settings in the B.C. interior and lower mainland. The experience with this pest in B.C. and the U.S. has also shown that it is infrequent in the landscape.

In agricultural environments, Y. malinellus populations levels are maintained below economic thresholds through the use of numerous biological control agents, through the use of the biopesticide Bacillus thuringiensis serovar kurstaki (B.t.k.) and indirectly, through various chemical pesticides applied to control other pest of Malus spp. maintain (Cossentine and Kuhlmann, 2000, 2001; Unruh et al., 2003).

It is known that there are natural biocontrols of Y. malinellus throughout Canada. For example, Nemorilla floralis is a tachinid fly that it known to attack the larva and pupa. The ichneumonid, Itoplectis maculator, is also known to attack the larval stage. Some species of Balaustium (predatory mites) are known to attack and kill up to 35% of the eggs of Y. malinellus (Cossentine and Kuhlmann, 2007). Natural predation of Y. malinellus larvae may also occur by insects such as the European earwig, ants, coccinellids and syrphids (Erven, 1979). In the Pacific Northwest, the parasitoid biocontrol agent Ageniaspis fuscicollis Dalman is known to attack eggs and young larvae and can cause greater than 40% mortality.

Yponomeuta malinellus is unlikely to reach economic damage thresholds in managed environments including organic fruit production. This pest has not generated additional costs for managed or cultivated environments because existing practices to produce apple have controlled the pest. The potential economic impact is rated low.

Yponomeuta malinellus is unlikely to degrade the environment, to alter the composition of natural ecosystems, or to cause human or animal health problems. The potential environmental impact is rated nil.

6.0 Risk Management Considerations

6.1 Plant Protection Regulations and directive D-96-02

Yponomeuta malinellus is included on Canada's list of regulated pest and in Schedule II (Restricted Movement within Canada) of the Plant Protection Regulations. Specific domestic and import requirements for areas infested with Y. malinellus are outlined in directive D-96-02, Plant Protection Requirements to Prevent the Introduction and Spread of Apple Ermine Moth on Malus Species. Domestic movement of Malus plants from B.C. to the rest of Canada require a combination of inspection, survey, chemical control, and a Movement Certificate. Similarly, the importation of Malus plants from infested countries has been required to meet one of the following three phytosanitary certification options: originate from a pest free area; be produced under a chemical control program; or be subject to post-harvest horticultural oil/water solution or fumigation treatment.

6.2 Standards of the International Plant Protection Convention (IPPC)

The Commission on Phytosanitary Measures (CPM) of the IPPC has been designated as a standard-setting phytosanitary authority of the World Trade Organization. According to the IPPC, contracting parties shall not require phytosanitary measures for non-regulated pests. The International Standard for Phytosanitary Measures (ISPM) No. 19, Guidelines on Lists of Regulated Pests (IPPC, 2003), requires that pests regulated by National Plant Protection Organizations meet the criteria for quarantine or regulated non-quarantine pests.

To be considered a quarantine pest, according to the IPPC's definition, an organism must be "a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled."

For a plant pest to be deemed to have potential economic importance, the following criteria should be met:

While the pest risk assessment identifies a potential for introduction and spread within Canada, it does not provide any instances where Y. malinellus is considered to have economic importance with respect to crops or the environment.

6.3 Pest Status and Trade in the United States

The U.S. does not regulate Y. malinellus and the detection of this pest on imported shipments entering the U.S. would not be subjected to regulatory action. Also, there is no regulation of interstate movement of host plants from the Pacific Northwest states where it is established. This observation is noteworthy as apple nursery stock and fruit production throughout the U.S. are reliant on nursery stock originating from Washington and Oregon where Y. malinellus is present. Based on official surveys conducted under the supervision of the United States Department of Agriculture (USDA), to date Y. malinellus has not spread and established outside of Washington or Oregon.

6.4 Trade and Economic Impacts

The pest risk assessment indicates that Y. malinellus is not a pest of significant economic importance in Canada. Deregulation of Y. malinellus is not expected to affect the volume of host plants moving in trade. Presently there are very few host species being exported to countries other than the U.S., and New Zealand is Canada's only current foreign nursery stock trading partner that regulates Y. malinellus. In addition, there are no requirements for Y. malinellus certification for exports to the U.S.

To meet regulatory requirements for Y. malinellus, CFIA resources have been used to deliver the Apple Ermine Moth Program and to survey for the pest outside of the B.C. regulated area. Nurseries shipping Malus spp. trees from B.C. to other areas of Canada have been required to implement the Apple Ermine Moth Program and pay associated fees.

7.0 Risk Management Decision

7.1 Consultation

A Risk Management Proposal (RMP) document proposing the deregulation of AEM was distributed to horticulture stakeholders for consultation from July 27th to September 27th, 2012. In the RMP, the CFIA recommended the deregulation of Y. malinellus based on the following rationale:

Although many stakeholders expressed support for the deregulation of Y. malinellus, some stakeholders in Ontario and Quebec expressed concerns regarding the CFIA's proposal. In spring 2014, further communication with concerned stakeholders was undertaken to respond to their comments and concerns and provide additional information supporting deregulation of Y. malinellus.

7.2 Decision

After thorough consideration of the scientific information, international obligations, and stakeholder comments, the CFIA is announcing, by way of this Risk Management Document, the deregulation of Y. malinellus. Yponomeuta malinellus no longer satisfies the definition of a quarantine pest. Current risk analysis demonstrates that it is not a pest of economic importance and its deregulation is necessary to align with the IPPC standards. Yponomeuta malinellus deregulation aligns with the U.S. approach and will facilitate trade.

The CFIA will work towards the removal of Y. malinellus from the Schedule II of the Plant Protection Regulations in the next regulatory review process.

Until this regulatory change is made and comes into force, the CFIA will revoke policy directive D-96-02: Plant Protection Requirements to Prevent the Introduction and Spread of Apple Ermine Moth on Malus Species. The revocation of Directive D-96-02 will take effect on August 21, 2014. Moreover, the CFIA will not be taking regulatory action to enforce item 4 (35) of Schedule II of the Plant Protection Regulations pertaining to the domestic movement restriction on apple (Malus spp.) plants from any area infested with Y. malinellus (apple ermine moth) to all other areas of Canada.

As part of the implementation of the deregulation, Y. malinellus will be removed from Canada's list of regulated pests and the Automated Import Reference Systems (AIRS) will be updated to reflect that the importation of apple (Malus spp.) plants are no longer subject to Y. malinellus requirements. A notification will be circulated to our trading partners through the World Trade Organisation to inform them that Y. malinellus is deregulated in Canada.

8.0 References

Carter, D.J. 1984. Pest Lepidoptera of Europe With Special Reference to the British Isles. W. Junk, Publ. Series Entomoligica Vol. 31. 431 pp.

Cossentine, J.E. and Kuhlmann, U. 2000. Status of Ageniaspis fuscicollis (Hymenoptera: Encrytidae), an introduced parasitoid of the apple ermine moth (Lepidoptera:Yponomeutidae). Canadian-Entomologist 132(5):685-689.

Cossentine, J.E. and Kuhlmann, U. 2001. Yponomeuta malinellus Zeller, Apple Ermine Moth (Lepidoptera: Yponomeutidae), pp. 90-94. In: P.G. Mason and J.T. Huber (eds.), Biological Control Programmes against Insects and Mites, Weeds and Pathogens in Canada 1981-2000. CABI Publishing, New York, USA.

Cossentine, J. E. and Kuhlmann, U. 2007. Introductions of parasitoids to control the apple ermine moth in British Columbia. Pages 13-19 in C. Vincent, M. S. Goettel, G. Lazarovits, eds. Biological Control: A Global Perspective : Case Studies from Around the World. CABI, Wallingford.

Dobesberger, E. and Garland, J.A. 2009. Plant Health Risk Assessement Yponomeuta malinellus (Apple ermine moth). Canadian Food Inspection Agency. PRA request No. 98-48 (Update No. 2)

Erven, H. 1979. The mixed forest, a model for the management of fruit and vegetables. (Does the lesser wood-ant play a role even in biological fruit culture?). Waldhygiene. 13:1-2. (In German) CAB Abstract.

Hewitt, C.G. 1917. The discovery of the European ermine moth (Yponomeuta) on nursery stock imported into Canada. Agriculture Gazette of Canada, Department of Agriculture., Ottawa, Ontario, pages 552-554.

Humble, L.M. and Humphreys, N. 1989. Apple ermine moth in southwestern British Columbia. Pest report, Pacific and Yukon Region, Pacific Forestry Centre, Canadian Forestry Service, Natural Resources Canada, 2 pp.

IPPC. 2003. International Standard for Phytosanitary Measures, ISPM No. 19, Guidelines on Lists of Regulated Pests, Secretariat of the International Plant Protection Convention, Food and Agriculture Organization of the United Nation, Rome, Italy.

ISPM. 2012. International Standard for Phytosanitary Measures, IPPC No.5, Glossary of phytosanitary terms, Supplement No. 2., Guidelines on the understanding of potential economic importance and related terms including reference to environmental considerations, Secretariat of the International Plant Protection Convention, Food and Agriculture Organization of the United Nation, Rome, Italy.

Kuhlmann, U., Carl, K.P. and Mills, N.J. 1998. Quantifying the impact of insect predators and parasitoids on populations of the apple ermine moth, Yponomeuta malinellus (Lepidoptera: Yponomeutidae), in Europe. Bulletin of Entomological Research 88:165-175.

LaGasa, E., Unruh, T.R. and Haskett, M. 1993. Apple ermine moth – Orchard Pest Management Online, Washington State University. []

Parker, D.J. and Schmidt, A.C. 1985. Apple ermine moth, Yponomeuta malinellus. Report for Agriculture Agri-Food Canada, Plant Health Division.

Unruh, T.R., Congdon, B.D. and LaGasa, E. 1993. Yponomeuta malinellus Zeller (Lepidoptera: Yponomeutidae), a new immigrant pest of apples in the northwest: phenology and distribution expansion, with notes on efficacy of natural enemies. Pan-Pacific Entomologist 69:57-70.

Unruh, T., Short, R., Herard, F., Chen, K., Hopper, K., Pemberton, R., Lee, J. H., Ertle, L., Swan, K., Fuester, R. and others. 2003. Introduction and establishment of parasitoids for the biological control of the apple ermine moth, Yponomeuta malinellus (Lepidoptera: Yponomeutidae), in the Pacific Northwest. Biological Control 28:332-345.

Zhang, B.C. 1994. Index of Economically Important Lepidoptera. CAB International, Wallingford, U.K. 599 pp.

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