Invasive Alien Species: The Spotted Wing Drosophila

close up of spotted wing drosophila on rasberry
Spotted wing drosophila, like this one sitting atop a raspberry, can wreak havoc on soft summer fruit. Photo credit: Laboratoire d’expertise et de diagnostic en phytoprotection, MAPAQ.

By J. Allen & L. Farmer

To the average Canadian, the words “invasive alien species” may conjure B-movie images of UFOs and one-eyed green men. To Canadian horticultural producers, these three words signal an ominous reality. This is particularly true for Canadian producers of soft summer fruit (e.g., cherry, blueberry, raspberry, blackberry, strawberry, peach, nectarine, apricot, and grape) due to the introduction and spread of one such alien invasive: Drosophila suzukii, the spotted wing drosophila (SWD).

In 2012, following the Agriculture Agri-Food Canada-led (AAFC) Canadian Minor Use Pesticide Priority Setting Workshop, in which SWD was identified as a priority pest, it became obvious that a different focus would be needed, as so little was known about the biology of the pest and how to control it. Under the leadership of the Canadian Horticulture Council and AAFC’s Pest Management Centre, and with the participation of provincial experts who were on the frontlines in facing the pest, an Invasive Alien Species Coordination Group was created. The mandate of the Coordination Group is to facilitate information sharing and coordination of research efforts to understand the pest and to find management solutions for two invasive species, one of which was the SWD.

To start, the Coordination Group created the SWD Technical Working Group, which is made up of provincial specialists, public sector researchers, and industry representatives. The SWD Technical Working Group is co-chaired by Tracy Hueppelsheuser (B.C. Ministry of Agriculture) and Leslie Farmer (Pest Management Centre). Since 2012, they have coordinated the sharing of information about SWD research and outreach activities taking place across Canada.

In late 2016, and into early 2017, the SWD Technical Working Group hosted four webinars, open to all. The purpose of the series was to share Canadian research and extension activities, as well as offer a discussion forum to identify future needs and gaps from both a research and in-the-field perspective.

Presentations and testimonials from across the country allowed attendees to learn about and discuss important issues, such as: monitoring and detection activities; the pros and cons of various trap types; the role of landscape attributes in population reservoirs and overwintering locales; conventional and organic pest management options; post-harvest recommendations; the use of physical barriers; early research results into sterile insect technique; physiological research (i.e. cold tolerance); and how biological control agents can become part of the management toolbox.

Some important facts shared during these sessions include:

  • SWD can overwinter in parts of Canada and survive in numerous wild hosts, including plants in the following genera: Ribes, Sambucus, Berberis, Prunus, Lonicera and Symphoricarpos species.
  • While choice abounds in trap and bait systems, ripening fruit still wins out in attracting the pest.
  • Mid-to-late season ripening fruit are at highest risk of attack.
  • Pest management research is ongoing, and effective, sustainable management will require multiple tools; this is not a pest that will be controlled by a single “silver bullet” solution.
maggot damage in plum

A spotted wing drosophila maggot pokes its head out from inside of a damaged plum. Photo credit: The B.C. Ministry of Agriculture

The high level of participation in the webinar series clearly demonstrates how plugged in and interested Canadian horticulture producers are in staying up-to-date with current research and activities that impact their operations.

Many of these same growers participate in the annual Canadian Minor Use Pesticide Priority Setting Workshop. The Pest Management Centre’s Minor Use Pesticide Program (MUPP) brings together growers, the provinces, pesticide manufacturers and the United States IR-4 Specialty Crops program to establish grower- selected crop/pest needs and match them with potential solutions on an annual basis. As the front-line guardians against pest issues, growers understand the impacts of persistent and emerging pest problems on their operations, thus their participation is critical in selecting the MUPP research priorities. Since 2011, the MUPP has been tasked with 23 minor use pesticide priorities for the management of SWD. Some of this work has been completed with data already submitted to Health Canada’s Pest Management Regulatory Agency for review. The new minor use registrations resulting from this work will provide Canadian growers with useful tools to help manage this challenging invasive pest.

maggot damage on peach

A spotted wing drosophila maggot sits atop the bruised and damaged remains of a peach. Photo credit: The B.C. Ministry of Agriculture

The Pest Management Centre’s Pesticide Risk Reduction program works with grower groups, the industry, provinces, and researchers to identify gaps in pest management and opportunities for pesticide risk reduction and to develop and implement strategies to address these gaps. The Program recently initiated a new strategy to address priority insect pests of soft fruit, and the SWD was identified as one of these priority pests. With the knowledge of current research and management gaps gained from the webinar series, this strategy working group is now determining priorities for action related to SWD under this reduced risk strategy. The overall goal of the strategy is to reduce risks associated with pesticide use in managing these pests and facilitate a move toward sustainable and effective management over the longterm. For more information about this initiative, please contact pmc.cla.info@agr.gc.ca.