Canada has over 800 species of wild native bees and these bees are essential to the pollination of many crops, and thus to food security. Sadly, several species’ populations are declining, and an increasing number of species are considered threatened with extinction. Wild bees face many threats, including habitat loss, climate change, pesticide exposure, the transmission of pathogens by domesticated bees (honeybees and commercial bumblebees), and malnutrition.

It is important to consider the nutritional and medicinal potential of flowers to help combat malnutrition and improve the health of bees. Unfortunately, plants with a high medicinal potential (i.e., naturally improve their health condition) are often deficient in amino acids that are essential for bees and are crucial for the survival and reproductive success of bumble bee queens.

Native bees foraging on flowers. A yellow-banded bumble bee gyne (new queen), left, and right, a sweat bee foraging on dwarf sunflower. Photos: Mathilde Tissier

Essentially, no single plant can meet all the needs of an animal. To identify the plants that meet both the nutritional and medicinal needs of bees, we seek to identify plants that when planted together provide great nutrition for bees (i.e., complementary plant associations). We have started a project with over 30 partners, including Wildlife Preservation Canada, to address this question. This project has multiple objectives, including:

  • Identify nutritionally complementary plant associations that improve the health and performance of wild bees;
  • Identify essential nutrient deficiencies in crop and native plant pollen and identify native plants with medicinal potential;
  • Survey producers to assess their interests and limitations in implementing favorable plants and associations identified

To address our first objective, in collaboration with WPC, we collected pollen from a variety of native plants, including red maple, willow species, and targeted wildflowers, to evaluate their nutritional and medicinal value for queens, both during reproduction and hibernation.

A brown-belted bumble bee colony in WPC’s breeding lab in 2021. Photo: Ellen Richard

In 2021 we assessed whether red maple pollen impacts the reproduction of the common eastern bumble bee and the brown-belted bumble bee. We found that queens fed with red maple pollen were 2x more likely to produce workers and 3x more likely to produce males and new queens (“gynes”)! In 2022 we are investigating willow and red maple pollen on WPC’s focal species for conservation breeding, the Special Concern yellow-banded bumble bee, and brown-belted bumble bees. On top of reproduction this year we will also assess whether these diets will decrease the prevalence of harmful parasites (i.e., have medicinal value) and test if late blooming wildflowers increase the chances of new queens hibernating successfully.

To address our second objective, in collaboration with agricultural producers, we are using sunflower as a simple method to improve the health of wild bees and commercial bumblebees in different agricultural environments in Quebec: blueberry fields, commercial vegetable greenhouses, and orchards. Sunflower is known as a medicinal plant for bees. Preliminary results highlight that dwarf sunflower is growing very well in a variety of environment and types of soil, attracts a great diversity of pollinators and improves the health of commercial bumble bees (thus reducing the risks of disease transmission to wild bees).

Below, dwarf sunflowers sown in a blueberry field in Alma, Québec. Photo credit : Aurélie Demers.

Above, dwarf sunflowers planted in commercial greenhouses producing tomatoes to improve the health of commercial bumblebees and reduce the risks of disease transmission to wild bees (when workers go out of the greenhouse to forage and interact with wildflowers and bees). Photos: Mathilde Tissier

This project will improve our knowledge of native bee nutritional requirements and allow us to identify plants and associations with high nutritional and medicinal values. By combining this new information to the consideration of the economic and social reality of agricultural producers, we will be able to identify relevant and science-based solutions for the conservation of bumblebees in Canadian farmlands.

Matilde Tissier

Mathilde is a scientist interested in the effects of nutrition on the performance of terrestrial animals. She obtained her PhD in ecology and biodiversity conservation in agricultural landscapes from the University of Strasbourg (France) in 2017, after completing a BSc and MsC in exchange between France, Quebec and British Columbia. She is now working on bumblebee conservation in collaboration with the agricultural community in QC and ON. Her project is funded by the Liber Ero Fellowship Program, which supports early career scientists working on biodiversity conservation in Canada.