A confusing bumble bee (Bombus perplexus) queen. Photo: Cole Blair

Providing insight into bumble bee parasites using their feces.

Conservation is considered a crisis discipline – a race against time. Reversing a declining species’ trajectory requires extensive knowledge about the reasons for decline. This of course demands that we identify what potential reasons should be investigated in the first place! Unfortunately, these stressors are not always so easily identifiable, and can occur in combination with several others. As you probably have guessed, this applies to bumble bees. The numerous threats to bumble bees complicates our view of their individual and related roles, as well as how to fix them.

The list of threats that bumble bees face is long. Climate change, habitat loss or change, pesticide use, and invasive species are factors that are most widely known to facilitate bumble bee declines. However, recent science has identified yet another threat to bumble bees – parasites.

Bumble bees are hosts to many parasites. Most are relatively harmless, but not all. My role within WPC’s Native Pollinator Initiative, partnered with the University of Toronto Scarborough’s (UTSC) Biodiversity of Urban Green Spaces (aka BUGS) lab and Dr. Mathilde Tissier (Laval University & Bishop’s University), was to jumpstart new research into the prevalence of two kinds of parasites in bumble bees across Southern Ontario and queens being brought into WPC’s bumble bee conservation breeding program. These parasites are the members of the fungal genus Vairimorpha (formerly called Nosema), as well as members of the genus Crithidia.

Vairimorpha spores can be differentiated from other objects by their unique capsule-like appearance and large size. Photo: Cole Blair

While there are many knowledge gaps surrounding these parasites, there is evidence that these parasites harm bumble bees in several ways. For example, gynes (new queens) that are parasitized by Vairimorpha may be less willing to mate. Similarly, Crithidia infections can reduce a queen’s ability to survive the winter and kickstart her colony and can greatly reduce workers’ foraging capabilities. Essentially, these parasites keep the bees from bumbling to their fullest abilities, especially when other stressors are also acting against the bees.

A Crithidia cell that can be identified. by their tapered shape, organelles, and flagellum. Photo: Cole Blair

Both Varimorpha and Crithdia spores can be gathered from bumble bee feces, which can be obtained quite easily with no harm to the bees. In fact, I’ve patiently watched hundreds of queens as they do their bees-ness in my petri dishes. This is also how these spores are believed to spread between bees; a parasitized bee may forage from a flower and poop out some parasites for another bee to pick up.

Common eastern bumble bee (B. impatiens) queen in her own personal porta-potty (aka ‘petri dish’). Feces is circled – one bee’s waste is another man’s research project! Photo: Cole Blair

I simply collect queens alongside the survey team in the field or from breeding queens in the lab, place them inside a quiet, comfortable cooler, wait for them to poop and then release them to keep bumbling. I then process and transfer each sample into small tubes for travel to the lab where I will analyze the samples under a microscope for the presence and abundance of these parasites.

Hey that’s me! Processing fecal samples in the field (left) and examining them at UTSC’s BUGS lab (right). Photos: Mathilde Tissier

I hope to reveal more about these parasites in wild bumble bee populations and importantly, help keep the conservation breeding colonies healthy!

Cole Blair

Bumble Bee Parasite Research Technician

Cole’s interest in conservation stems from an active outdoor upbringing as a child and was only solidified during his time as an Undergraduate at Trent University, where he dedicated much of his time to exploring the beautiful scenery of Central Ontario. Currently pursuing a Master of Environmental Science degree at the University of Toronto Scarborough, Cole hopes to further hone his scientific capabilities and help some cute critters along the way.