Friday, November 30, 2018

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:

    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.

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