Bumblebee species can survive for up to a week underwater
Bumblebees are at home in town and country habitats but now researchers have found at least one species that is even more adaptable: it can survive underwater.
Scientists have revealed queens of the common eastern bumblebee, a species widespread in eastern North America, can withstand submersion for up to a week when hibernating. With bumblebee queens known to burrow into soil to hibernate, the researchers say this ability could help them survive flooding in the wild.
The team said its next priority was to explore whether the results hold for other species of bumblebee.
Dr Sabrina Rondeau, of the University of Guelph in Canada, said: “We know that about a third of all bumblebee species are in decline currently [but] it’s not the case with [the common eastern bumblebee].” She added that the team was keen to learn whether flood tolerance could play a role in their resilience.
Rondeau and her co-author, Prof Nigel Raine, made their discovery when a mishap in the laboratory led to water getting into containers in which hibernating queen bees were kept. “After that, of course, curiosity led the way to conducting a full experiment with a lot of repetitions,” said Rondeau.
Writing in the journal Biology Letters, the scientists describe how they took 143 unmated, hibernating queens of the common eastern bumblebee and placed each in its own plastic tube containing damp topsoil. The tubes were then fitted with perforated lids and kept in a dark refrigerated unit for a week.
After checking the bees were still alive, the researchers kept 17 tubes as controls and added cold water to the remaining 126. While the queen was allowed to float on top of the water in half of the tubes, it was pushed under the water by a plunger in the others.
For both conditions, a third of the tubes were each left for eight hours, a third for 24 hours and a third for seven days, simulating different flooding conditions. The team subsequently transferred the bees to new tubes and monitored their survival.
Survival rates were similar regardless of the duration and conditions the queens had been subjected to – 88% of the controls, and 81% of the queens that were submerged for a week were still alive at eight weeks. Queens with a higher weight had a greater chance of survival.