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RMD-11-01: Pest Risk Management Document - Drosophila suzukii (spotted wing drosophila)

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Date issued: 2011-07-29


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.

Table of Contents

1.0 Executive Summary

Drosophila suzukii was first detected in British Columbia in 2009 and has been detected in most fruit growing regions of Canada as of the fall of 2010. Surveys indicate that the pest is present in the major fruit growing regions of North America and there does not appear to be any practical measures which could prevent further spread into and within Canada. Eradication is not a possibility. After review of the science based information available, the Canadian Food Inspection Agency (CFIA) has decided not to add D. suzukii to the List of Pests Regulated by Canada.

2.0 Purpose

This risk management document (RMD) describes the regulatory rationale and regulatory decision for D. suzukii (spotted wing drosophila).

3.0 Scope

This RMD is the formal record of the pest risk management decision that was taken following completion of the CFIA's pest risk assessment (PRA) in 2010 and observations with respect to the presence of D. suzukii in Canada, North America and the rest of the world.

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

4.0 Definitions

Definitions for terms used in this document can be found in the Plant Health Glossary of Terms or the IPPC Glossary of Phytosanitary Terms.

5.0 Background

Drosophila suzukii is a pest that can attack most temperate fresh fruits, including economically important fruits such as cherries, blueberries, raspberries and strawberries. The first report of D. suzukii in North America was in California during the summer of 2008. In 2009, the pest was reported as causing serious economic damage in cherry and other stone fruits in California. It has subsequently been reported in the U.S. states of Oregon, Washington, Florida, North Carolina, South Carolina, Michigan, and the Canadian Provinces of Quebec, Ontario, Manitoba, Alberta and British Columbia.

The Plant Health Risk Assessment Unit prepared preliminary information regarding D. suzukii in the fall of 2009. Based on the information provided in the PRA, internet and media reports and presentations made by U.S. state officials dealing with D. suzukii, the CFIA communicated with federal and provincial partners to raise awareness that D. suzukii could be expected to be detected across Canada in 2010 and that it had potential to be an economic pest for horticultural crops.

6.0 Pest Risk Assessment Summary

The following information is taken from the Pest Risk Assessment #2009-55, Drosophila suzukii (Matsumura) - Spotted wing drosophila, completed on September 21, 2009 and updated on February 9, 2010.

Pest Biology

  • Life History: This fly has up to 13 generations under ideal conditions, such as those found in areas of central Japan. In California 3 to 10 generations are expected. The life cycle can be as short as one week at 28 °C. Adults overwinter in sheltered areas. The larvae and eggs cannot withstand temperatures near freezing for more than 4 days. Pupation is either in the fruit or on the surface of the soil.
  • Host Range: This fly lays eggs in near-ripe to ripe soft-skinned fruit, including Rubus, Ribes, Fragaria, Prunus and Vitis. It is also found on Cornus kousa, a Japanese ornamental dogwood. Up to 65 adults have emerged from a single infested cherry.
  • Means of Dispersal / spread: Flight is local and most spread has likely been by the movement of infested fruit. Plants without fruit are not expected to carry this fly.


The native habitat of this fly ranges from northern China and southern Siberia to northern India south and east to Hainan Island in China. It is also known from Korea, Thailand and Burma. It has also been introduced to Hawaii, and has been reported from Spain and Italy. It is now widespread in California, Oregon, Washington and Florida, and is present elsewhere in the U.S. It has been identified in Quebec, Ontario, Manitoba, Alberta and British Columbia.


The most likely pathway for the movement of D. suzukii into uninfested areas is fresh fruit for consumption from infested areas. Natural spread of this insect is expected to be slow. Conversations with entomologists indicate that windy weather events may hasten spread. Following a single detection in the Greater Vancouver area in 2009, D. suzukii was found to be widespread throughout the lower Fraser Valley in 2010.


  • Entry: High. Has already occurred.
  • Establishment: High.
  • Extent of potential distribution: Any area of Canada with relatively mild winters similar to Hokkaido in Japan (average January temperature -12 °C to -4 °C). Preliminary modelling suggests the entire commercial fruit-growing area of Canada is at least partially at risk, with greatest risk (related to greatest number of potential generations of the fly) in British Columbia, southern Ontario and the Maritime provinces.


  • Economic: High. In warm areas (Japan, California) this fly has shown itself to be a serious pest of cherries, caneberries (Rubus), strawberries, blueberries and grapes. Even in northern Hokkaido and Aomori prefectures there have been outbreaks on grapes and blueberries. Increased use of chemical controls may upset other Integrated Pest Management strategies.
  • Sociological: Caneberries and strawberries are widely planted in home gardens. In some areas, home vineyards also bring certain social values. Large losses due to this fly in home-grown fruit crops could negatively affect quality of life values.
  • Environmental: Medium. Premature losses of wild caneberries, strawberries and blueberries could affect nutrition levels of vertebrates (birds, bears, etc.), especially should this fly become well established in natural areas. Applications of chemical pesticides to these crops to combat this pest will be in addition to current pesticide applications and the most effective pesticides known are broad-spectrum pesticides (cypermethrin, malathion, acetamiprid). Acetamiprid is also highly toxic to bees. Several bird species are already in decline, and there is evidence to suggest that native bumble bees and other pollinators are also already in decline.
  • Overall rating of consequences: High
  • Uncertainty: Low


On the available reviewed evidence, this fly poses a serious threat to Canada's fruit growing and wine industry.

Technical Issues for Consideration

  • Mitigation measures: Trapping has been shown to be effective at reducing adult populations. Improved management of fruit orchards, such as removing fallen fruit and better sanitation practices may also have an impact. Chemical pesticides are available. Some organic alternatives are also available, although they are not as effective. Nets of 0.98mm mesh size have been shown to exclude this fly.
  • Detection and identification: Flies can be baited with fruit fly lures. Information acquired in BC during the 2010 growing season indicates that D. suzukii demonstrates a preference for ripening fruit over baited traps. Early detection is critical to management. Drosophila suzukii adults are light yellow or brown flies with red eyes. Males have a black spot on the leading edge of each wing near the tip. Please note that this is not a definitive characteristic as a few other Drosophila spp. have this feature. Females lack black spots on the wings and have a large ovipositor with saw-like teeth which are much darker than the rest of the ovipositor

7.0 Risk Management Considerations


Drosophila suzukii was first observed in North America in the summer of 2008; numbers and distribution increased quickly through the 2009 and 2010 growing seasons. The pest is now widespread in fruit-growing regions of the U.S.. Canada imports approximately 827,000 tonnes ($1.3 billion) of fresh fruit annually from U.S. states where the pest is known to occur. Imported fruits include, but are not limited to, cherries, grapes, peaches, plums, apricots, nectarines, raspberries and blueberries. Every area of Canada which has received shipments of fresh fruit from these areas has likely been exposed to D. suzukii.

A single fruit infested by D. suzukii may potentially result in the establishment of a new population. For example, up to 65 adults can emerge from a single infested cherry.

D. suzukii has the potential to establish in most, or all, of the fruit-growing areas of Canada. Climate matching suggests that D. suzukii could establish throughout eastern North America south of Quebec city. Since this fly is already established in Florida and in the western States, it may naturally migrate to Canada on both sides of the continental divide.

Potential Trade Impacts


Domestic regulation within Canada is not considered to be feasible as D. suzukii has the potential to spread into and within Canada by natural means, notwithstanding any regulatory measures that could be put in place by the CFIA.


Australia, New Zealand and Mexico have recently implemented phytosanitary restrictions to prevent the introduction of D. suzukii. However, the U.S. the European Union and Asian countries do not regulate D. suzukii. Interestingly, this pest was detected almost simultaneously in both North America and southern Europe.

Market opportunities for host fruit in Australia and New Zealand have traditionally been limited due to other pest issues. Mexico has been reported as implementing phytosanitary restrictions on fresh cherries from the U.S.. At the present time, Canada does not have market access for fresh cherries to Mexico. Accessing export markets with D. suzukii based phytosanitary restrictions may require additional phytosanitary measures.

Existing Domestic, Provincial or other Programs

Because D. suzukii is a new pest to Canadian agriculture, provincial partners have been updated on the potential spread of the pest. This is the first time a species of Drosophila has been identified as a primary fruit pest for the Canadian fruit production zones.

The 2010 detections of D. suzukii in Canada were based on a combination of CFIA regulatory surveys, Agriculture and Agri-Food Canada (AAFC) research surveys and surveys conducted by provincial authorities primarily for the development and provision of agronomic advice to growers and producers. Not all jurisdictions received the same degree of survey so D. suzukii may occur in more locations than were reported in 2010.

Socio-Economic Impacts

D. suzukii continues to establish and spread within Canada. It causes direct damage to fruit and is expected to be an economic pest to agriculture and is likely to also move into,both fruit and ornamental plantings in home gardens. Public awareness of this pest is expected to increase as it becomes established in urban environments.

International Obligations

The IPPC describes a quarantine pest as: "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". Official control for quarantine pests is defined as "the active enforcement of mandatory phytosanitary regulations and the application of mandatory phytosanitary procedures with the objective of eradicating or containment". Measures applied on imports should be consistent with the principles of non-discrimination (ISPM No. 5, Supplement No. 1, Guidelines on the interpretation and application of the concept of official control for regulated pests.) In other words, in order to implement import restrictions for D. suzukii, there must be equivalent official measures to eradicate or contain and prevent the spread of D. suzukii within Canada.

8.0 Pest Risk Management Options

During the development of this RMD a number of options for reducing the risk of further introduction and spread of this pest were considered. The options that were considered include: prohibiting the movement of fresh fruits such as cherries, strawberries and raspberries or requiring cold treatment or fumigation of these fruits when they are from infested areas.

The available science, the nature and size of the pathway and the rapid spread of this pest in 2009 and 2010 indicate that none of these options would likely be effective and feasible. There are no technical measures available to the CFIA which could efficaciously prevent further spread to or within Canada.

9.0 Risk Management Decision

As there is no possibility to prevent spread within Canada, nor is there a reasonable possibility of eradication, the CFIA has taken the decision not to include D. suzukii in the List of Pests Regulated by Canada of this pest.


  • Drosophila suzukii has been detected in five provinces in Canada as of November 2010.
  • Drosophila suzukii is present in the U.S. and there are no regulatory measures in place to prevent further spread.
  • Drosophila suzukii will spread to and within Canada by natural means, notwithstanding any regulatory measures that could be put in place by the CFIA.

Potential consequences:

  • Drosophila suzukii is expected to spread within Canada, to areas with suitable climactic conditions and where hosts are available.
  • Some potential markets for Canadian fruit may be closed or require the implementation of additional technical measures in order to meet the foreign country's phytosanitary import requirements that may be related to D. suzukii.

Next Steps:

  • The RMD will be posted on the CFIA website.
  • No changes in import requirements are required as a result of this decision.
  • No changes to import inspection procedures are anticipated as a result of this decision.
  • There are no anticipated human resources implications or financial costs.

10.0 Stakeholder Communications

The CFIA has reported the presence of D. suzukii in Canada on the North American Plant Protection Organization (NAPPO) Pest Alert website and continues to share biological and technical information about this pest with provincial governments and national industry stakeholders, as it becomes available.

Major Federal, Provincial and Territorial stakeholders will be informed directly of the decision to not regulate D. suzukii. A copy of this RMD will be circulated to key stakeholders. These stakeholders include:

  • CFIA Program officers, inspection staff, etc.
  • AAFC
  • Pest Management Regulatory Agency (PMRA)
  • Provincial departments of Agriculture
  • Industry stakeholders

11.0 References

  • CFIA PRA # 2009-55, Plant Health Risk Assessment Drosophila suzukii (Matsumura)Spotted wing drosophila.
  • Pest Fact Sheet for Drosophila suzukii, CFIA, September 2009
  • Drosophila suzukii (Diptera: Drosophilidae) Spotted wing drosophila A pest from the EPPO Alert List, EPPO, 2010
  • Host fruit import statistics courtesy of Market and Industry Services Branch, Agriculture & Agri-Food Canada
  • Personal communications, BC Plant Protection Advisory Council Drosophila suzukii Committee

12.0 Endorsement

Approved by:

Chief Plant Health Officer