Bumblebee queens surprise by surviving underwater

That bumblebee queens survive being underwater can be good news for the important pollinator, which is under great pressure. The experiment suggests that the bumblebees can withstand climate-driven floods that threaten winter hibernation in bumblebee hives.

– That the bumblebees survive under water is an encouraging sign in a worrying trend where bumblebee populations are declining worldwide, says Sabrina Rondeau to the AFP news agency.

She is the lead author of the study Unveiling the submerged secrets: bumblebee queens’ resilience to flooding which is published in the journal Biology Letters.

Got water on experimental hops

The first sign that the bumblebee queens can tolerate being under water came after an accident in the laboratory. Sabrina Rondeau studied the effects of pesticides in the soil around bumble bee queens when several of the tubes with bumble bees came under water.

– I was very disappointed. Fortunately, few queens had ended up underwater. But I didn’t want to lose them and took care of the hops. To my great surprise, the bumblebee queens survived, says Sabrina Rondeau.

None of the people she had spoken to in her long studies of bumblebees had any idea that bumblebees survive underwater.

Eight out of ten survived

Rodeau set about a new experiment to understand what was happening. Here, 143 hibernating bumblebee queens were placed in tubes. Some of the queens were not immersed in water as a reference group. Others were placed floating in water, while still other hops were placed under water from eight hours to seven days.

According to the report, the queens were placed in new tubes with soil taken from an area where bumblebees hibernate. Queens marked as dead were stored at room temperature before the dead status was confirmed.

Not only did 17 out of 21 (81 percent) of the queens that had been underwater for seven days survive. They were still alive eight weeks later. In the control group, 88 percent, or 15 out of 17 queens, survived.

May cause greater survival

The long-term impact on the health of the bumblebees and how the queen’s long stay under water affects the colony cannot be answered without more research, according to Rondeau.

The hops used in the experiment are an American species that has not experienced the same decline in population as many other hop varieties.

– We wonder if the resistance to flooding could be one of the reasons why they do so well. The study needs to be repeated on other bumblebee species to see how widespread this survival is. But it is encouraging to see that flooding may not be as big a threat as we have thought until now, says Sabrina Rondeau.