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A new invasive weevil that is turning berry buds into duds in British Columbia

A new invasive weevil that is turning berry buds into duds in British Columbia

By Michelle Franklin, Paul Abram, and Tracy Hueppelsheuser

 

Most of the weevils we find in raspberry and strawberry fields in the Fraser Valley of British Columbia (BC) are nocturnal, so you would be hard pressed to find adult weevils without venturing out at night with your headlamp or flashlight.  However, in 2019 a curious small black weevil was observed during the day in a backyard raspberry patch in Abbotsford, BC.

The first specimens of this weevil were collected by Provincial Entomologist and coauthor, Tracy Hueppelsheuser from the BC Ministry of Agriculture, Food and Fisheries and sent to taxonomists and co-authors, Dr. Patrice Bouchard from the Canadian National Collection and Dr. Robert Anderson from the Canadian Museum of Nature for their expert identification. It turned out that this weevil was indeed new to the Fraser Valley, BC.  This tiny (2.5 – 3mm), black, long nosed weevil was the strawberry blossom weevil, Anthonomus rubi, which is native to Europe, Asia, and North Africa. This was the first observation of this species in North America.

Strawberry blossom weevil is not just a pest of strawberries.  It is able to feed and reproduce on a wide variety of plants in the family Rosaceae, including other economically important berry crops such as raspberries and blackberries.  Adult weevils overwinter in the leaf litter and become active in the spring.  After mating, the female chews a hole inside a closed flower bud, lays her egg inside, and then clips the stem below, killing the bud and preventing fruit development.  The weevil larva then develops inside the bud and emerges as an adult about a month later when temperatures are warm in the summer.  In its native range, the weevil  completes a single generation each year.

I started my position as a research scientist in July 2020, specializing in small fruit entomology and Integrated Pest Management at the Agassiz Research and Development Centre of Agriculture and Agri-Food Canada.  With help from Paul Abram (Agriculture and Agri-Food Canada), Tracy Hueppelsheuser (BC Ministry of Agriculture, Food and Fisheries), and crop consulting company, ES Cropconsult we hit the ground running, completing surveys in the Fraser Valley in the summer 2020 to determine the distribution and associated host plants of the strawberry blossom weevil.  We found adult weevils on cultivated plants (e.g. strawberry, raspberry, blackberry, and rose) and wild hosts (e.g. salmonberry, thimbleberry, Himalayan blackberry, and wild rose).  Our survey found this species to be well established throughout the Fraser Valley from Richmond to Hope.

However, there is some good news for potential natural pest control.  Later during the summer we saw parasitoid wasps around weevil-damaged Himalayan blackberry buds.  We knew that some species of parasitoid wasps had the potential to be natural enemies of the weevil. Parasitoid wasps lay eggs on weevil larvae and their offspring often develop on the larvae resulting in their death. This behaviour has been successfully used as biological control of other weevil pests for decades. Hence, we initiated natural enemy surveys by collecting damaged buds from the field.  Although COVID protocols restricted lab access, I monitored damaged buds in my temporary laboratory (a.k.a home garage) and within a few weeks parasitoids emerged! Over the summer, we had over 150 parasitoids emerge from strawberry blossom weevil damaged buds. With the help of taxonomist and co-author, Dr. Gary Gibson from the Canadian National Collection, we identified the metallic-colored parasitoid to the genus Pteromalus. Future work is needed to identify the parasitoid to the species level, determine its origin (native to North America or inadvertently introduced from another continent), and determine its impact on strawberry blossom weevil populations.

I am continuing to work with my co-authors to understand the biology of this new pest and its natural enemies, with the goal of using this knowledge to develop sustainable pest management strategies in the future.  If you are interested in this new berry pest, please contact me at michelle.franklin@agr.gc.ca.

Free online access to article (until October 4, 2021): Click here

Links to information pages:

Strawberry blossom weevil – Anthonomus rubi Herbst – Canadian Food Inspection Agency (canada.ca)

Anthonomus rubi Detection in Canada Anthonomus rubi D tection au Canada | Phytosanitary Alert System (pestalerts.org)

Strawberry Blossom Weevil – Invasive Species Council of British Columbia (bcinvasives.ca)

Full article: https://doi.org/10.4039/tce.2021.28

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Berm Outreach Day: The importance of enhanced non-crop habitat for beneficial insects in intensive agricultural landscapes

by Dillon Muldoon, MSc student

Me on one of my newly planted berm research plots. Photo by Jenni Dunning.

While driving up highway 400 for that cottage getaway in the Muskokas, you’ll pass by a little slice of Ontario agriculture on some of the darkest soil you’ve ever seen. But be careful: If you blink, you might miss this beautiful place known as the Holland Marsh. Located 50 km north of Toronto, the Holland Marsh is known for its intensive production of carrots, onions, and over 60 other horticultural crops. The Marsh contributes over 1 billion dollars to the Ontario economy through the production, processing, and shipment of vegetables.

For my MSc project, I’m looking at ways to enhance ecosystem services in the Holland Marsh. Ecosystem services are benefits humans gain from ecosystems, which can include water and air purification, carbon sequestration, agricultural pest management, and crop pollination. My research specifically focuses on enhancing non-crop areas so that they can provide better habitat for pollinators and natural enemies of crop pests. Studies show that the enhancement of “naturalized” non-crop areas (e.g., hedgerows, field margins, riparian areas, mowed grass) with vegetative and floral plantings can help support the abundance and diversity of beneficial insects within an intensive agricultural system. The habitat provided for these beneficial insects can offer several ecosystem services to growers, from pollination of crops to assisting with crop pest control. Until recently, the Holland Marsh had almost no non-crop habitat. In 2010 the Holland Marsh Drainage System Canal Improvement Project was initiated, and at its completion in July 2016, 19 km of canals had been relocated and dredged, and 10 km of berms (dykes) had been expanded to improve safety and efficiency. This expansion of the berms increased the amount of non-crop habitat in the Holland Marsh. My study investigates how different vegetative enhancements on the canal berms might affect beneficial insect complexes and agricultural pest populations at the Holland Marsh. I’m using both active and passive trapping to assess the abundance and diversity of natural enemies, pollinators, and insect pest populations in two different vegetative enhancements throughout the growing season.

Me at Berm Day explaining the importance of non-crop habitat. Photo by Jenni Dunning.

Although vegetative enhancements can be beneficial, stakeholders were concerned about the possibility that the enhancements could provide a refuge for pests (e.g., insects, weeds, vermin) and that they may not be aesthetically pleasing. To address these concerns, I orchestrated a public and grower outreach day (Berm Day) on July 5, 2019 with help from funding by the Entomological Society of Ontario. The goal of Berm Day was to connect with the public and growers about the importance of enhancing non-crop habitat to support beneficial insects in intensive agricultural systems. I hoped to create a dialogue surrounding the importance of ecosystem services, and to disseminate some of my findings. My study has shown that vegetative enhancements support a greater abundance of natural enemies than the natural berm vegetation and increase floral resources for pollinators. The enhancements have not provided a refuge for primary insect pests of the crops grown at the Holland Marsh.

Overall, Berm Day was a great success. I connected with local growers, members of the public, master gardeners, conservation authorities, and members of the Ontario Ministry of Agriculture, Food, and Rural Affairs, over some fresh baked goods and coffee. We opened a dialogue about the project and shared ideas for future research, including management approaches and new seed mixes to improve the aesthetics appeal of the plantings. Everyone who attended left with a package of Ontario Native Seed Mix to plant at home, which was generously provided by Syngenta’s Operation Pollinator Multifunctional Landscapes.

I have heard once or twice that diversity is the spice of life, and within an intensive agricultural system, it can play an important role by offering numerous benefits for both growers and natural ecosystems. The conservation and enhancement of non-crop habitat can help provide ecosystem services in the Holland Marsh by increasing and supporting beneficial insects.

A special thanks to all the volunteers, advisors, the Muck Crops Research Station’s staff, Paul Hoekstra, and the Entomological Society of Ontario for making this day possible.

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Risky Buzz-i-ness

By Nicole McKenzie, PMRA

Growing up is a continuous lesson in assessing risks.

In my case, those risks included going for a double salchow with the risk of taking a bad fall, pushing my limits on my bike with the risk of an accident around every corner, or choosing an insect-filled educational path that was once considered risky for girls and women.

But with these risks come opportunities, and learning which risks are worth taking, and which are best avoided, is a critical lesson we all learn through experience and opportunity. Luckily for me, I survived the risks I took, and the lessons they taught me prepared me for a job that I love.

For the last decade, I have been an Evaluation Officer with the Pest Management Regulatory Agency (PMRA), the pesticide-regulating wing of Health Canada.

In an effort to join the #scicomm science communication revolution, I want to do a better job of explaining what I do.

No, I don’t pop a wheelie on ice while wrangling bees in a forest, but I do work that is almost as interesting.  I said *almost*.

What DO you do, then?

I deal with pollinators of the insect kind.  I look at how pesticides affect bees that collect and move pollen from male and female flower parts. This process is called pollination and it helps to produce fruit like apples. Pollinators are vital to not only Canada, but to the entire world’s food supply. I assess pollinator pesticide risk, which means I analyze research from some Entomology Society of Canada members as well as the greater pollinator community. With a team of scientists, I dissect the data from research studies and organize it around a risk assessment framework. The framework holds up the data so the team can see ALL of the highs and lows of the risk.  

From here we can step back and take in the whole risk picture gallery.

From the picture emerges a Pollinator Risk Management Plan that can be put in place to help safeguard our bees and food.

The Bikes and the Bees

Every day, we take what are deemed acceptable risks like driving a car at high speeds, and we try to prevent unacceptable risks like contracting measles that could affect our families and ourselves.

Deciding which risk is worth taking can be overwhelming. My risk assessing jam is The Risk Song by Risk Bites. It both winds my gears and chills me out.

Our method to assess risk is a lot like grinding through bike gears from smallest to largest. A better way of explaining this is by writing about going for a bike ride. But not just any bike ride, a big one like a Century Bike Race where you ride 100 km in one day, something I hope to accomplish this summer.

A Century Bike Race is risky, but like anything, it can be assessed and a plan developed to manage the risk.

To assess the risk, I first completed 3 tests as I trained on my bike. Like steps, each test relied on the one before to gather information on the risks.

The stepped tests (or tiers as we call them in the risk assessment world) start very basic and move toward a more realistic set-up closer to mimicking the actual bike race. At each step, if an effect was seen (or a risk identified) another test was completed.

Effect information:

Tier 1: Basic bike riding skills

  • TEST: Emergency stop or trying-to-stop-quickly-from-a-fast-speed.
  • EFFECT = Falling over. This might be the fastest (unintentional) way to end my race.

Tier 2: Group riding skills

  • TEST: Riding with the flow in a group of cyclists with bikes in front, behind and on both sides.
  • EFFECT = I wobble side to side as I ride.  No one wants to ride beside that.

Tier 3: Bike racing skills

  • TEST: Entering some shorter bike races.
  • EFFECT = I have never done a bike race before. *NOTE: I have competed in short distance triathlons, but ask any roadie about how these don’t count*. Bike racing seems a little like running with bulls, except with extra metal, spokes and wheel parts. Ouch.

Exposure Information:

It’s not enough to list effects seen from my bike race “tests”; I need to know about the race. I need to know details about what I could be exposed to during the race. This could include the road conditions, the type of race, the timing of the race and so much more.

Risk Assessment = Effects + Exposure

Using a framework, I compared the effects seen in the 3 tiered tests to what I expect to be exposed to during my bike race, and came up with this Risk Management Plan:

 

TEST TYPE RACE EXPOSURE INFORMATION RISK IDENTIFIED MANAGEMENT STEPS
Tier 1

Basic bike riding skills
  • The race is mainly on paved roads
  • There is a hill at 87 km
  • There is a gravel road at 88 km, at the bottom of the hill
  • Race is in the summer
  • I want to finish well
 Falling off bike
  • REDUCE THE RISK
    • Wear a helmet
    • Carry a bike repair kit
    • Carry water and food
    • Carry emergency contact information
    • Practice emergency stopping
Tier 2

Group riding skills

 Wobbling as I ride
  • REDUCE THE RISK
    • Practice riding in a straight line
    • Practice riding in a group
Tier 3

Bike racing skills

 I have never done a bike race before
  • REDUCE THE RISK
    • Practice climbing hills
    • Practice biking on gravel
  • MINIMIZE EXPOSURE
    • Enter smaller bike races before the big one
    • Wear weather appropriate clothing and sunscreen

If my bike analogy is still lost on you, connect with me on Twitter and I’ll try comparing it to landing a double axel instead. In the meantime, here’s a handy interactive infographic to explain the risk assessment process using caffeine as an example.  

The Bees and the Bikes

Assessing pesticide risk to pollinators is similar to assessing bike race risk. There are of course different pollinator tests for each of the 3 tiers and different exposure details needed for plants and pesticides but the process is the same. Each tier gets more specific and more realistic to what and how a pollinator could react when encountering a pesticide in the environment. Here is how a general pollinator risk assessment works starting with the tiered tests:

Effect information examples:

Tier 1: Individual bee effects

  • TESTS:
    • Observe individual bees after they are fed pesticides mixed with sugar
    • Observe individual bees after a pesticide drop is placed on their back

Tier 2: Semi-field effects

  • TESTS:
    • Observe bee colonies that are placed under tents with pesticide treated plants
    • Observe bee colonies that are fed pesticides mixed with sugar and/or pollen

Tier 3: Full-field effects

  • TEST: Observe bee colonies that are placed in fields of pesticide treated plants

Exposure information examples:

    • The type of pesticide and how it works
    • The plants that are to be treated with the pesticide
    • The timing of the pesticide applications and when the plants bloom
    • If pollinators are found on or attracted to the treated plants
    • The amount of pesticide found in the plant parts that pollinators may feed on or touch

Risk Assessment = Effects + Exposure

Just like with my bike race we use a framework to compare the effects with the exposure information but there is more to consider that can complicate the process.  

We also strive to understand the natural history of pollinators and the way crops are grown and harvested in Canada.   This crucial information is then overlaid on the exposure information and the effects seen. This melding together of ALL the collected information results in, you guessed it, a Pollinator Risk Management Plan.

Example of Pollinator Pesticide Risk Management Plan Steps

Some management steps that crop up in plans I’ve helped put together include:

  • Not allowing pesticides to be applied to any plant while it flowers
  • Reducing the amount of pesticide applied to a level below where the risk lies
  • Changing the timing of a pesticide application from before to after flowering
  • Eliminating the use or method of a pesticide application

Risky Buzz-i-ness keeps me busy

Working with pollinators has taught me that nothing is as straightforward as it seems. The science changes all the time, as do the risks as we learn more about bees, their behaviour, and how plants are grown in Canada.

There is one thing I do rely on, and that is how pollinator work is NEVER boring.

If you want more information about the pollinator risk assessment process… or to give me bike race tips here’s some links:

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Love, Tiny Flies, and One Big Opportunity for Researchers to Work Together Helping Farmers on Both Sides of the Border ~ Foreign Perspectives

Me at the University of Guelph Elora Research Station.

by Elisabeth Hodgdon, Ph.D. Candidate, University of Vermont

“It’s a story of unrequited love,” says Dr. Yolanda Chen, my Ph.D. advisor, describing our research on pheromone mating disruption. Mating disruption, a pest management strategy that involves inundating a field with synthetic sex pheromone, prevents male insects from finding their mates because they can’t cue in on individual female pheromone plumes. As a result, the males become confused and die without mating. During my time as a Ph.D. student, I’ve spent a lot of time in Vermont and Ontario becoming intimately familiar with the sex lives of swede midge, a serious invasive pest of cruciferous crops.

Swede midge (Contarinia nasturtii, Diptera: Cecidomyiidae) first arrived in North America in the 1990s in Ontario. Vegetable growers started noticing that their broccoli, cauliflower, and cabbage plants were deformed and didn’t produce heads, and that their kale leaves were twisted and scarred. On canola farms, yields decreased because of distorted plant growth. The culprit, identified by Dr. Rebecca Hallett and her research group from the University of Guelph, was a tiny fly called swede midge. The midge, only about 2 mm long as an adult, is seemingly invisible to farmers because it is so small. Within a few years, the midge had made its way from Ontario to Québec and other provinces, and into New York and Vermont.

Female swede midge on cauliflower.

At the University of Vermont, we are the only research lab in the US working on this pest, which is currently causing up to 100% yield loss of organic broccoli and kale in our state. Naturally, it made sense for Dr. Chen to reach out to Dr. Hallett in Guelph for collaboration to investigate management options for this pest. Together, they wrote a grant funded by the USDA to conduct pheromone mating disruption research on swede midge that would take place in both Vermont and in Guelph.

This where I enter into the story. I jumped at the opportunity to join Dr. Chen’s lab, not just because I’m interested in insect pest management, but also because of my continuing love affair with Canada. I grew up in Vermont, a small state that borders Québec and has had lots of influence from our northerly neighbors: a history of French-Canadian immigrants, widespread availability of decent quality poutine, and signage in our largest city en français, among other things. I grew up learning French and visiting nearby Montréal and later went on to study agriculture at McGill University’s Macdonald Campus. I was thrilled at the opportunity to spend more time in Canada during my Ph.D. program.

Me and University of Guelph entomology graduate students at the ESC meeting in Winnipeg last fall: Charles-Étienne Ferland, Jenny Liu, me, Sarah Dolson & Matt Muzzatti (left to right). Photo credit: Matt Muzzatti.

I have gotten to know the English-speaking provinces better through my graduate work as a visiting Ph.D. student in Dr. Hallett’s lab in Guelph. Although many Canadians, especially those from nearby Toronto, describe Guelph as being a “small farm town,” it felt like a real city, especially coming from Vermont. I fell in love with Guelph — the year-round farmers market, old stone buildings, beautiful gardens, and emphasis on local food. The large sprawling farms just outside the city were the perfect places for me to do my research on swede midge pheromone mating disruption, which required lots of space between plots and treatments. Back in Vermont, where the farmland is wedged in small valleys between mountain ranges, we just don’t have the scale of crop production that there is in Ontario.

Josée Boisclair, me, Yolanda Chen, and Thomas Heer (left to right) at IRDA this summer getting ready to transplant broccoli for mating disruption research.

Working with Dr. Hallett opened up many doors and expanded my network in Canada. Last year, my advisor and I started a collaboration with the Institut de recherche et de développement en agroenvironnement (IRDA) in St-Bruno-de-Montarville, Québec. Earlier this winter, I practiced my French and mustered up the nerve to give two extension presentations on my swede midge work to francophone farmers in Québec. I was surprised at the number of people who came up to me after my talk, appreciative that I was making an effort to communicate with them in French rather than English. They were genuinely interested in working together with my research group across the border to help strengthen our research efforts to manage swede midge.

In all the time I’ve spent in Canada (which at this point can be measured in years), I can’t think of a time when I’ve felt unwelcome. On the contrary, I am impressed with how open most Canadians are to foreigners. I hope that we can continue to work together, despite language barriers, differing political systems, and other potential challenges, to gain traction in our efforts to find solutions for swede midge and other shared invasive species in the future.

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