Un-BEE-lievable: The Buzz on Native Bee Conservation in Canada

Guest post by University of Toronto-Scarborough MEnvSc Candidate Rachel Siblock

Unless you’ve been living under a rock (much like native mining bees in Canada), you’ve probably seen the numerous campaigns to “Save the Bees”. Bee species across the globe are in decline. There are many factors that contribute to this decline, such as pesticide use, colony collapse, disease, habitat loss, and climate change¹. Many of these factors interact with one another, exacerbating the consequences and impacts. Conservation efforts are being implemented to try to stop the loss of these pollinators, and the valuable services they provide to humans. Canada is no exception. There are local, provincial, and national policies and programs operating and currently being developed in order to reduce the impacts of these threats. In the past few years, programs like The Bee Cause, Bees Matter, Feed the Bees, and others have implemented programs and recommendations in order to increase the bee populations in Canada. Honey Nut Cheerios has even campaigned to get the public engaged and involved in the conservation of bees. These programs, however, all have one common issue: they focus their efforts on Honey Bees. 

An example of a campaign by Honey Nut Cheerios, focusing on honey bees. 

There are no native honey bees in Canada. The most well-known bee in Canada was not even present in the country until it was introduced from Europe in the 1600s². The European Honey Bee was intentionally introduced to Canada for honey production, and since has increased in number dramatically, both in farmed and wild colonies. Honey bees have large colonies, allowing them to be easily managed and farmed. They also pollinate crops and produce honey, which may make them seem more economically valuable than their native, non-honey-producing counterparts. However, there have been unexpected impacts of the introduction of the European Honey Bee on native bee species in Canada.

            There are over 800 native bee species in Canada. While there are many different types of bees in Canada, the best understood group of native bees are bumble bees. Bumble bees have the ability to buzz pollinate, which allows them to obtain pollen from plants with pollen that is difficult to extract. Many of these plants are economically valuable, such as kiwi and blueberry crops. This, along with general pollination, makes managed populations of bumble bees worth several billion dollars annually³. Bumble bees naturally have low genetic diversity and can be subject to inbreeding depression, leading to declining populations and making the some species more vulnerable to extinction⁴. Threats can then interact with these low population levels, and intensify population loss. 

A male Rusty-patched Bumble Bee, one of Canada’s native bee species. It is currently listed as endangered in Canada.

Aside from facing the same threats as honey bees, native bumble bees are also threatened by the very presence of honey bees. Competition for resources with honey bees is a major threat to native bumble bees. A study performed in the United Kingdom found that bumble bees at sites with high honey bee density were significantly smaller in body size when compared to their relatives at sites with low honey bee density⁵. An additional study discovered a reduction of native bumble bee colony success when colonies were experimentally exposed to honey bees⁶. Honey bees generally produce larger colony sizes which can store a larger amount of resources than bumble bees. They also have the ability to communicate with one another about valuable floral resource locations⁷. Honey bees have a larger foraging range than native bumble bees, and have an increased ability to forage on introduced plant species⁷. These adaptations allow honey bees to outcompete native bumble bees, and commandeer sparse resources in the area.

            Threats from honey bees do not just end at competition; pathogens and parasites specifically adapted to honey bees have been shown to have the ability to spread to wild bumble bee populations. Managed honey bees are known to carry higher than natural levels of pathogens⁸, which can be transmitted to wild bumble bee populations when the bees interact. In particular, two pathogens endemic to honey bees, C. bombi and N. bombi, are wreaking havoc on bumble bee populations. While these pathogens do not have lethal effects, their sublethal effects can be devastating to colonies. These pathogens cause reduced pollen loads, a decline in flowers visited per minute, slower growth rates of colonies, decreased queen reproductive rates, shortened life spans and diminished colony growth⁸. With small populations already, entire bumble bee colonies can be wiped out by these pathogens. Honey bee parasites, such as the Small Hive Beetle, have also been shown to be able to spread to bumble bee colonies, where they consume the wax, pollen, and nectar stores of hives⁸. While honey bees have co-evolved with these parasites and pathogens for eons, bumble bees have not had the time to adapt to these threats, making them much more vulnerable to these hazards. 

Small Hive Beetle infestation in a honey bee colony. 

But why do we care about losing native bees? The same concerns about the loss of honey bees applies to native bees. Native bee species pollinate crops and flowers, which we depend on for food. It is estimated that about one in three bites of food we consume can be traced back directly to pollination by bees and other pollinators. However, native bees have been found to be more effective pollinators than honey bees. Some plant species in Canada rely solely on native bees for their pollination. With the loss of native bees, these plants will also become endangered, along with many other food crops requiring pollination. Additionally, there is a severe lack of research into native bees. Research tends to focus on honey bee populations, resulting in much more knowledge of honey bee behaviours, adaptations, actions, and responses to stressors. The truth is, we don’t know much about native bee species in Canada. We have no idea what the consequences of the loss of these species will be. However, this does not excuse us from protecting these bees. If anything, this lack of knowledge should increase our urge to protect them, so we have the opportunity to learn about them in the future.

            The native bee species in Canada share little life history traits with the European Honey Bee⁸, making many conservation efforts that focus on honey bees unsuccessful. Focusing conservation efforts on one species may not address the specific needs of native bees. In addition, by focusing on improving honey bee populations, there will be increased stress on native bees, which will lead to a decline in their populations. If we continue with these conservation strategies, we may threaten native species further.

            An increase in honey bee populations will increase parasite and pathogen levels in native bees, and also increase the competition between honey bees and native bees. So what can you do to focus conservation efforts on native Canadian bees? For starters, avoid the use of pesticides, which will decrease already low populations⁸. Improve your knowledge of bee species, and report invasive or introduced species in areas used by native bee species. Plant a wide variety of native plants with high pollen and nectar concentrations to ensure newly emerging bees have the resources they need to survive. And finally, avoid tilling, mowing, or burning in areas where native bee species, particularly ground dwelling species, are known to live. With increased knowledge of native bee needs, and species specific conservation efforts, it is hoped that native bee species will begin to rebound. Let’s BEE positive!

BEE Informed – To get involved with native bee conservation check out these links:

Native Pollinator Initiative – Wildlife Preservation Canada

Bumble Bee Recovery – Wildlife Preservation Canada

Help Native Bees – Conservation Halton 

Native Bee Information – Canadian Wildlife Federation

BEE-bliography:

    1.     Pettis, J.S., and K.S. Delaplane. 2010. Coordinated responses to honey bee decline in the USA. Adipologie 41:256-263.

    2.     van Engelsdorp, D., and M.D. Meixner. 2010. A historical review of managed honey bee populations in Europe and the United Sates and the factors that may affect them. Journal of Invertebrate Pathology 103:80-95.    

    3.     James, R., and T.L. Pitts-Singer. 2008. Bee Pollination in Agricultural Ecosystems. Oxford University Press, USA.

    4.     Zayed, A., and L. Packer. 2005. Complementary sex determination substantially increases extinction proneness of haplodiploid populations. Proceedings of the National Academy of Sciences of the United States of America 102:10742-10746.

    5.     Goulson, D., and K. Sparrow. 2009. Evidence for competition between honey bees and bumble bees: Effects on bumble bee worker size. Journal of Insect Conservation 13:177-181.

    6.     Thomson, D. 2004. Competitive interactions between the invasive European honey bee and native bumble bees. Ecology 85:458-470.

    7.     Goulson, D. 2003. Effects of introduced bees on native ecosystems. Annual Review of Ecology, Evolution, and Systematics 34:1-26.

    8.     Colla, S.R. 2016. Status, threats and conservation recommendations for wild bumble bees (Bombus spp.) in Ontario, Canada: a review for policymakers and practitioners. Natural Areas Journal 36:412-426.

Image Sources:

  1. https://bringbackthebees.ca

  2. https://inaturalist.com

  3. http://beeaware.org.au/archive-pest/small-hive-beetle/#ad-image-0

Floral diversity increases bee abundance and diversity

*This is a guest post by Aswini Kuruparan- student in my 'Causes and Consequences of Biodiversity' course.

Bees are amongst the most crucial pollinators in the world and are critical for the success of our food crops. In fact, bees and other pollinators are responsible for the pollination of 87% of all flowering plant species (Lerman, 2018). However, due to the changes that humans have imposed on the environment through land use and agricultural practices, we see declines in both the numbers and diversity of bees (Nicholson, 2017). Recent evidence has been compiled to show that the composition of agricultural fields, tillage and lawn mowing frequency can significantly affect bee population size and diversity by directly affecting floral diversity. 

Agricultural fields can see more bee abundances and diversity with more floral diversity

The role of bees in the pollination of our food crops is essential to the success of global food production and feeding people around the world (Photo M. Cadotte).

Studies have shown that increasing floral diversity in agriculture can increase the size and diversity of bee populations attracted to those fields. In fact, one experiment looked at the correlation between floral diversity and population growth in stingless social bees (Kaluza, 2018). Their results indicate a positive correlation between floral diversity and bee population growth. They attribute this positive correlation with the continuous food supply available in florally diverse environments. In monocultures, all plants bloom around the same time period thus providing a narrow time interval in which bees would have sufficient food for population growth. A more diverse agricultural system would be accompanied by a larger range of blooming periods thus providing the food needed for bee populations to grow. Another experiment conducted in the vineyards of Austria came to a similar conclusion. This experiment also found that forage availability is the most significant factor to affect species richness in wild bees (Kratschmer, 2018). These findings indicate that we can promote bee diversity through diversifying the variety of floral plants in and around agricultural fields.

Another factor that indirectly affects bee population sizes and diversity is human activity in the form of soil tillage. In the study above conducted on the Austrian vineyards, the experimenters also compared the effects of no-tillage to alternating tillage and found that alternating tillage displayed slightly increased wild bee abundance and diversity relative to a no-tillage environment (Kratschmer, 2018). In this experiment no tillage was defined as a vineyard that had not undergone tillage in 5 or more years and alternating tillage was defined as a vineyard where every other row was tilled 1-3 times a year. The reasoning behind why more diversity and numbers of bees were found in alternating tillage sites was because those sites displayed higher forage availability and increased flowering plant species richness in comparison to untilled soils. Although the study found that directly increasing floral diversity had a higher impact on bee diversity, it should not be overlooked that soil tillage can also increase bee diversity and that these findings can open future research into the impacts that other steps in agriculture have on bee diversity.

Outside of agricultural practices, how often homeowners mow their lawns also affects bee biodiversity and numbers by affecting floral diversity. A study put this to the test by mowing lawns either once, twice or three times a week (Lerman, 2018). Their study revealed that mowing lawns less frequently led to increased bee biodiversity and abundance. They observed that lawns that were mowed every 3 weeks had 2.5 times more flowers than the ones mowed every 1 or 2 weeks thus providing more vital resources to bees. They suggest that homeowners minimize the frequency at which they mow their lawns to benefit bee conservation efforts by allowing for the growth of more flowers on their lawn. This shows that everyday people outside the agricultural industry can also help conserve bee diversity.

Homeowners can help increase bee biodiversity by decreasing their lawn mowing habits

Recently, Walmart has filed for a patent on autonomous robotic bees as a solution to the dwindling bee population, but this approach is not as feasible as preserving current bee diversity and making changes to promote their population growth (Potts, 2018). The economic cost of manufacturing and running these robotic bees to sustain our global food crops would be hundreds of billions of dollars. Comparatively, the pollination services by bees and other insects that are free of cost have a monetary value of over 200 million Canadian dollars (Kratschmer, 2018). It is more financially feasible to fund efforts to promote bee diversity through diversifying our agricultural systems than to build and operate these robotic bees. Moreover, robotic bees would also not be able to sufficiently capture the diverse traits possessed by various bee species to efficiently pollinate specific types of flowers. The time and resources needed to fine-tune traits which have already been perfected over years of natural selection in real bees into robots would be put to better use towards conserving and growing our bee populations.

Although it is important to acknowledge that our actions are partly to blame for the decline in bee diversity over the years, it is also important to realize that we can make changes to enhance bee diversity from here on. These studies have shown that bee diversity can be improved by increasing floral diversity through diversifying the vegetation in and around our crops, coupled with homeowners reducing the number of times they mow their lawns and further investigating how various steps in agriculture like tillage can affect bee diversity. With this in mind, it is critical that future funding is put towards conserving bee diversity rather than towards replacing them with robotic bees.

References

Kaluza, B. F. (2018). Social bees are fitter in more biodiverse environments. Scientific Reports, 8. doi:https://doi.org/10.1038/s41598-018-30126-0

Kratschmer, S. (2018). Tillage intensity or landscape features: What matters most for wild bee diversity in vineyards? Agriculture, Ecosystems & Environment, 266, 142. doi:10.1016/j.agee.2018.07.018

Lerman, S. B. (2018). To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards. Biological Conservation, 221, 160. doi:10.1016/j.biocon.2018.01.025

Nicholson, C. C. (2017). Farm and landscape factors interact to affect the supply of pollination services. Agriculture, Ecosystems & Environment, 250, 113. doi:10.1016/j.agee.2017.08.030

Potts, S. G. (2018). Robotic bees for crop pollination: Why drones cannot replace biodiversity. Science of the Total Environment, 642, 665-667. doi:10.1016/j.scitotenv.2018.06.114