New data indicates 60 bee species and morpho-species can be found on Vancouver Island farms, including the threatened Western bumble bee and the non-native Eastern bumble bee.
The study, conducted by Bonnie Zand, involved collecting samples of bees from 19 different farm sites across the Island between 2021-22. Areas included Cowichan Valley, Comox Valley, Victoria, Nanaimo and Qualicum Beach. More than 7,500 specimens were examined.
The purpose, Zand explained, was to collect baseline data to find out what species exist on Vancouver Island in agricultural systems. While the most recent Bees of British Columbia checklist from 2018 gives an indication on general bee species for the Pacific region, it doesn't specifically focus on those that frequent agricultural areas.
"On Vancouver Island specifically we actually don't know which bee species are present on agricultural systems here," Zand told the News Bulletin. "That puts our agriculture in quite a vulnerable place because we don't know [which bees are] important within those systems, we don't know what bees are pollinating what plants and we don't even know what bees are there."
Of the 60 species identified, five were found on all 19 farms, while 13 species were unique to individual farms. Bumblebees were the species most commonly detected, with the yellow-faced bumblebee present on every farm, making up about 23 per cent or 1,737 of the total specimens. The second most common was the black-tailed bumblebee, at about 12 per cent or 905 specimens, then the yellow-fronted bumble bee at 11 per cent or 887 specimens.
Some species were only identified as morpho-species, which means that while the genus or sub-genus could be identified, the specific species could not be determined with complete accuracy.
Bumblebees being the most common was not a surprise to Zand, who explained that the genus is social and colonies will contain several hundred individuals.
"I would expect to see quite a few of them just because they have high population numbers [and] are present during the summer. Also, the main method that we used for doing this work are called blue vane traps and they're known to be highly attractive to bumblebees."
The threatened Western bumblebee was identified on nine farms, accounting for 0.37 per cent of the specimens collected. There was a single individual Eastern bumblebee, a non-native introduced species, and six samples of the non-native punctate spatulate-masked bee.
Zand said she was "really interested" to see the Western bumblebee.
"It used to be a really important agricultural pollinator but has undergone some pretty severe declines in the last 20 years, so seeing it showing up on a number of different farms was quite encouraging to see that it is still here on Vancouver Island."
On the other end, she was concerned to see the Eastern bumblebee, a species that escaped being used to cultivate greenhouses in Fraser Valley. While it could have just been a worker that got out of a human-controlled colony, Zand noted, it could also be a worker from an escaped established colony.
"That's one you're kind of watching for in concern that it may become established on Vancouver Island, and we're not sure what impact that would have on the other species here, if this additional bumblebee species moved in."
If someone does come across an Eastern bumblebee, Zand recommends they take a photo and post it on iNaturalist, so researchers can make note of where they're appearing.
(Abundance of all species collected from farms on Vancouver Island. The 10 most abundant species are on the left, the remaining species are on the right. The y axis denotes the number of specimens collected. Note the different scales for the two graphs. Bars are colour coded by bee family. (Bonnie Zand image)
Five species documented in the study were not recorded on the Island in the most recent Bees of British Columbia checklist. Those were the tripartite sweat bee, the carinate armored-resin bee, Titus's sweat bee, the thistle long-horn and the masked bee. Zand said this doesn't necessarily mean they're not supposed to be on the Island, with the exception of the masked bee.
"There is still a lot we don't know about our bees and our pollinating fauna in general," she explained. "The fact that I detected them on Vancouver Island but they weren't detected in the region on that recent study doesn't necessarily mean they haven't been here the whole time, and just haven't been noticed. We do lack a lot of this baseline data."
Zand notes in her study that the presence of these species on the Island may indicate a range expansion or that the bees may have been undetected in past surveys. As much of B.C. is still under-surveyed for native bees, the study suggests it is likely that many species' ranges have not been fully documented.
The masked bee is the exception, as it is a European species first recorded in eastern Canada in 2011, and unofficially on Vancouver Island in 2021 through posts on iNaturalist.
One of the hoped-for outcomes of the study, Zand said, is to broaden people's understanding of the diversity of native bees.
"We really tend to focus on honeybees and bumblebees but just realizing that there are all these other species, and they're doing things like nesting in soil, nesting in stems, some of them will nest in your raspberry canes if you don't prune them down super low. Those will actually produce a nesting resource for this bee species that will then pollinate the raspberries."
She added that people interested in supporting native bees can reduce pesticide use, leave areas of their yard "messy and not cleaned up" to serve as nesting spaces, and ensure lots of flowers are available from early spring to late fall.
"These are all things people can do that support pollinators and that support a high diversity of pollinators," Zand said. "Those are things I would love people to take away from the study, just how awesome our native bees are."
The full study can be read online at https://mailchi.mp/vifarmmonitoring/pollinators.
