A new study has found that large swarms of insects , such as bees or locusts, can generate enough electrical charge in the air, similar to those seen during thunderstorms. It’s something that could have exciting implications for our understanding of how animals can affect the atmosphere.
In a storm, small ice particles rising in columns of air can brush up against larger fragments falling to the ground, creating a conveyor belt of charges that exaggerates potential gradients between cloud tops, clouds and the ground below.
While the charge buildup is essentially invisible, the effects are not. Once the gradient reaches a tipping point, ionized channels form and the equilibrium is effectively evened out in what we see as lightning.
A wide variety of factors can determine the magnitude and positioning of potential gradients, from cloud movements to precipitation, but until now no one had really considered the impact of biological phenomena.
“Essentially, we always looked at how physics was influencing biology, but at some point we realized that biology could also be influencing physics,” said Ellard Hunting , a biologist at the University of Bristol. “We are interested in how different organisms use the static electric fields that are practically everywhere in the environment.”
To test whether bee swarms can cause observable changes in atmospheric electricity, the researchers carried out measurements at a field station at the University of Bristol School of Veterinary Sciences, Langford, UK. The team deployed additional electric field monitors in combination with video cameras to measure the electric field and swarm density, and waited for bees in nearby hives to swarm naturally. Experts found that bee swarms change atmospheric electricity between 100 and 1000 volts/meter . By analyzing the proximity of the bees to each other in the swarms, the team found that the denser the swarm, the stronger the electric field.
“How insect swarms influence atmospheric electricity depends on their density and size,” said Dr Liam O’Reilly, a biologist at the University of Bristol. “We also calculated the influence of locusts on atmospheric electricity, as locusts swarm on biblical scales, 460 square miles in size with 80 million locusts in less than one square mile; their influence is probably much greater than that of bees.”
According to the study, the flapping of many tiny wings in a swarm of insects can perturb electrical charges in an air column enough to change the electric field of the air in a local area in a big way. As insect wings flap, they can knock off electrons from dust, moisture, and insect parts in an air mass . By doing this, the negatively charged electrons can become loose, creating an electrical potential gradient that can be measured.
The research team used the same reasoning to explain why their estimates withstood tests by bees and other swarming insects. They also determined that a significant locust swarm could produce charge densities similar to those found in thunderstorms by increasing individual locust charges to plague-size levels.
“We recently discovered that biology and static electric fields are intimately related and that there are many unsuspected links that can exist at different spatial scales, ranging from microbes in the soil and plant-pollinator interactions to insect swarms and perhaps the global electrical circuit. Interdisciplinarity is valuable here: it may seem like electric charge only lives in physics , but it’s important to know how aware the entire natural world is of electricity in the atmosphere,” explained Giles Harrison, an atmospheric physicist at the University of Reading.
Referencia: Ellard R. Hunting, Liam J. O’Reilly, R. Giles Harrison, Konstantine Manser, Sam J. England, Beth H. Harris, Daniel Robert. Observed electric charge of insect swarms and their contribution to atmospheric electricity. iScience, 2022; 105241 DOI: 10.1016/j.isci.2022.105241