Slow-learning bumblebees are just as successful as smart ones and live longer, suggests a new study that researchers say calls into question the assumption that brain superiority is better in the beleaguered pollinators' world.
The study by three researchers from Canada, England and New Zealand shows slow-learning bumblebees collect food at similar rates as their cognitively superior brethren.
Canadian researcher Nigel Raine said he and his team used a novel approach whereby a bumblebee colony was split in two, with one half having access to the "flight arena" where the bees could be monitored visually, while the other half had access to the outside world to forage for real flowers.
The queen, he said, was rotated between the two halves to ensure the colony didn't degenerate into the "Lord of the Flies."
First, Raine said, they put colours and numbers on each bee and watched as they headed into an artificial meadow of fake blue and yellow flowers.
"Bumblebees have an innate preference for blue and, all else being equal, they go to blue," said Raine, an environmental science professor at the University of Guelph.
The fake blue flowers didn't have a hidden well of sugar that serves as a reward, he explained, only the yellow ones contained the sweet solution.
"So we're trying to get the bees to ignore the blue flowers and learn to associate this new yellow flower with a reward," Raine said.
All of the bees eventually learned to fly to the yellow flowers, but it allowed Raine and his team to ascertain a measure of learning – through how quickly they went to those flowers and how "faithful" they remained to the sweet ones.
"It's a relatively simple learning test, but it gives us a measure of learning speed and how well they've learned the task," he said.
Then they swapped the bees and let those bees out into the field, armed with tiny microchips super-glued to their backs that tracked when they left the colony and when they returned. Researchers also measured the bees' mass upon exit and arrival, Raine said.
"So we can infer the amount of nectar she brings back," he said.
"We were really surprised when we looked at the data."
The upshot: no real differences between the slow-learning bees and fast-learning ones.
While the study wasn't set up to specifically measure lifespan, researchers were able to track the last time each bee left and never returned – thus, assuming they died outside. The data showed slower-learning bees lived longer, Raine said.
This was different than Raine's research from about a decade ago when he found that fast-learning bees in London, England brought nectar back to colonies at a "substantially higher rate than slower learning bees.
"It suggests we're dealing with a much more complex system and learning is only useful to bees and other animals in more adverse conditions, such as an urban setting like London, where the distribution of resources like flowers are more patchily distributed," Raine said.
The implications are revelatory, he said.
"We have this implicit assumption that learning is a good thing and being smarter is good and being adaptive is a good thing, which I think it is for humans," he said.
"The thinking shifts from being smart is always good to being smart is good under adverse conditions."
Bees are important wild plant and crop pollinators and colonies suffered catastrophic losses in Ontario in recent years. The province has banned an insecticide – used in farming – to help pollinators such as bumblebees.
The problems bees face are complicated, Raine said.
"There are lots of things interacting from habitat and climate changes to other factors like higher levels of parasites and pathogens in bees," he said.
This research, he said, now shows that cognitive challenges have a real effect on bees' success.
"We need to understand better how they're using these landscapes to conserve them better and conserve the pollination services they provide free of charge because it's really important for food production and maintaining diverse habitats across Canada."
The study was published recently in the scholarly journal Scientific Reports.