Swarms of western honeybees can generate an electric charge of 1000 volts per metre, a voltage density greater than thunderstorm clouds and electrified dust storms
Swarming honeybees can produce a greater electric charge for their density than a thunderstorm cloud.
The discovery came as a surprise when Ellard Hunting at the University of Bristol in the UK and his team were tracking weather at a field station near their university. They noticed their electric field monitors recorded a jump in atmospheric electric charge despite no storm activity. However, at the same time, nearby western honeybees (Apis mellifera) were swarming, a behaviour the insects do when looking for a new home.
“When I looked at the data, I was kind of surprised to see that it had a massive effect,” says Hunting. It was already known that individual bees carry a small charge, but a voltage of this magnitude had never been documented in swarming honeybees before.
The team deployed additional electric field monitors in combination with video cameras to measure the electric field and swarm density, and waited for the bees at nearby hives to naturally swarm. The researchers recorded three swarms passing the monitors for around 3 minutes at a time. They found that the bee swarms created an electric charge ranging from 100 to 1000 volts per metre. By analysing the proximity of bees to each other in the swarms, the team found that the denser the swarm, the stronger the electric field was.
Hunting compared the bees’ highest charge to previous data on meteorological events like fair-weather storm clouds, thunderstorms and electrified dust storms, and found dense bees swarms outcharged them all. Their charge density was around eight times as great as a thunderstorm cloud and six times as great as an electrified dust storm.
It isn’t known if this ability is useful for bees or an accidental product of friction between their wings and the air – like a person rubbing a balloon on their clothes. The charge could serve an unknown purpose as bees use electric fields to forage for food, says Victor Manuel Ortega-Jiménez at the University of Maine.
Jiménez wonders if the same phenomenon is happening with other flying, swarming animals like birds and bats. “These are all interesting questions that this paper opens to investigate,” he says.
Journal reference: iScience, DOI: http://dx.doi.org/10.1016/j.isci.2022.105241
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