Insect swarms can create electrical charges, study finds

Electric charges are everywhere, both positive and negative. As opposite charges pull each other, just as charges repel each other. Although these forces often go unnoticed on a human scale, they can have an overwhelming effect on small animals and plants.

For example, honey bees collect a positive charge on their wings – which they beat more than 200 times per second – glide over molecules in the air and use it to attract negatively charged pollen. They can also detect and adjust the electric fields of flowers. Spiders spin negatively charged webs to trap positively charged insects, and use the electric fields of trees to float through the air. Positively charged hummingbirds attract negatively charged plant pollen into their beaks. The environment is electrifying to say the least.

But it is less than previously thought. A study published Monday in the journal iScience found that when insects such as honeybees and locusts gather in swarms, the individual charges in each creature create electric currents in the atmosphere as strong as lightning. Although more research is needed to confirm their precise climate results, the trillions of tiny particles that make up the atmosphere can help explain basic weather patterns like cloud formation and fill in the picture of the complex environment around us.

Victor Ortega-Jimenez, a biomechanics researcher at the University of Maine who was not involved in the study, said the study is the first to confirm the large-scale electrical effects animals have on the atmosphere and “opens up a lot of possibilities.” He said.

“Insect swarms are everywhere – you can see them in mosquitoes, you can see them in bees, you can see them in locusts and birds,” he said. “Imagine all that potential.”

The study of how electrostatic forces affect living organisms in ecosystems is known as electrical ecology. Ellard Aden, a biologist at the University of Bristol in England and the study’s author, helped develop this field of inquiry with several colleagues. Their research has often focused on the way insects—especially honeybees in university-housed hives—interact with their crowded environments.

Scientists measure the strength of the electric field in the atmosphere by calculating the difference between the Earth’s surface and the air above it. This is known as the potential gradient, and is important for predicting the weather and understanding the chemical composition of the air. Regular changes in the gradient affect how animals move through their environment.

In the past few years, researchers at Bristol have discovered that insects not only take charge when they fly, but also fight each other and walk in conflicting areas. They looked at how this charge affects insect behavior, in part by watching the university’s honey bees fly and then measuring the electrical currents produced by the plants they visited. In doing so, Dr. Aden observed that there was a “significant effect” on the potential gradient in the atmosphere as the insects hovered.

He contacted Giles Harrison, a meteorologist at the University of Reading in England, and, together, measured how the density of bee swarms changed the electric field in the atmosphere. They found that very dense swarms can increase the local potential gradient to 10 times its original value.

The researchers then extrapolated their findings to individual desert locusts and the mass swarms the insects are famous for. Based on these models, he said, some locust plagues, which include billions of insects over hundreds of square miles, can affect electrical currents in the atmosphere like lightning storms.

“I think this is amazing,” said Dr. Ortega-Jimenez. “Thunder!”

“There are a lot of unknowns,” he added, such as how exactly the changes in insects’ exposure to electric fields will affect the climate, what effects the changes will have on the ecosystem, and whether the jaw charges will benefit the insects in any way.

“It’s an open question how these swarms and these charges affect not only the atmosphere, but the surrounding biology,” he said. “At the level of evolutionary trends, there is still no history.”

Dr. Aden acknowledges these limitations and unknowns, but says additional studies show that insect swarms can affect the amount of aerosols and ions in the air and influence cloud formation. “There are many unexpected links that can exist at different spatial scales, from soil microbes and plant-pollinator interactions to insect swarms and the global electrical cycle,” he said.

All this is electrically connected, it is a network of living and non-living, small and large scales.

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