Electric charges are everywhere, both positive and negative. Just as opposite charges pull together, like charges repel each other. While these forces often go unnoticed on a human scale, they can have outsized effects on small animals and plants.
Honey bees, for example, accumulate a positive charge when their wings — which beat more than 200 times a second — rub against molecules in the air, and use it to attract negatively charged pollen; They can also detect and modify the electric fields of flowers. Spiders spin negatively charged webs that stretch out to catch positively charged insects, and they use the electric fields of trees to levitate through the air. Positively charged hummingbirds attract negatively charged plant stamens to their beaks. The ecosystem is buzzing with electricity, albeit on a tiny scale.
But it’s less tiny than previously thought. A study published Monday in the journal iScience found that when insects like honey bees and grasshoppers gathered in swarms, the individual charges in each creature bunched up to create electric fields in the atmosphere as strong as those produced by thunderstorms are generated. While additional research will be needed to confirm their exact climatic effects, the trillions of tiny bodies that electrify the air could help explain fundamental weather events like cloud formation and complete a picture of the complex environment around us.
Víctor Ortega-Jiménez, a biomechanist at the University of Maine who was not involved in the research, said that this study is the first to confirm the large-scale electrical effect of animals on the atmosphere and that “it opens up many possibilities . “
“Insect swarms are everywhere — you can see it on mosquitoes, you can see it on bees, you can see it on grasshoppers and birds,” he said. “Imagine all this potential.”
The study of how electrostatic forces affect living beings in an ecosystem is called electrical ecology. Ellard Hunting, a biologist at the University of Bristol in England and author of the study, along with a number of colleagues helped develop this area of research. Her research has often focused on the way insects — particularly honeybees in hives maintained at the university — interact with their charged environment.
Scientists measure the strength of the electric field in the atmosphere by calculating the difference between the charge on Earth’s surface and in the air above the ground. This is called the potential gradient and is important for predicting the weather and understanding the chemical composition of the air. Regular changes in gradient even affect how animals navigate their environment.
In recent years, the Bristol researchers have found that insects not only charge when they fly, but also by rubbing against each other and walking on friction surfaces. They studied how this charge affected insect behavior, in part by watching the university’s honey bees fly around and then measuring the electric fields generated by the visited plants. At the same time, Dr. Hunting found that there was a “profound effect” on the atmosphere’s potential gradient when the insects swarmed.
He contacted Giles Harrison, a meteorologist at the University of Reading in England, and together they measured how the density of honey bee swarms changed the electric field in the atmosphere. They found that the densest swarms could increase the local potential gradient up to 10 times its original value.
Then the researchers extrapolated their findings to the attacks of individual desert locusts and the densities of the massive swarms the insects are famous for. Based on these models, they claimed that some locust plagues, which may include billions of insects across hundreds of square kilometers, affect the atmosphere’s electric field to the same extent as thunderstorms.
“I find that amazing,” said Dr. Ortega-Jiménez. “Thunderstorm!”
He added that “there are a lot of unknowns” about how insect-driven electric field changes actually affect climate, what impact the changes have on ecosystems, and whether swarm charges benefit insects in any way.
“It’s an open question how these swarms and these charges affect not only the atmosphere but also the biology around them,” he said. “At the evolutionary trend level, there is no history yet.”
dr Hunting acknowledged these limitations and unknowns, but said further research would likely show insect swarms could affect the density of aerosols and ions in the atmosphere and affect cloud formation. “There are many unexpected connections that can exist across different spatial scales, from soil microbes and plant-pollinator interactions to insect swarms and the global electrical circuit,” he said.
It’s all electrically connected, he added, a network of living and inanimate, small and large scales.
