Insect swarms contribute to electricity in the air

Bees and grasshoppers in large numbers have more influence on the atmospheric electric field than a passing thunderstorm, scientists have found.

The Earth has a gigantic electric field. This so-called ‘atmospheric field’ is affected by many factors, from rain and thunderstorms to dust particles and even the rotating wings of a helicopter. Meteorologists use knowledge of these influences to predict the weather. Now it turns out that the atmospheric field can also be disturbed by swarms of insects. For example, biologists from the University of Bristol (Great Britain) write in the journal iScience.

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Static electricity

Electricity is closer than you think. Just rub an inflated balloon firmly over your hair. You will see that it appears to ‘stick’ to the balloon. The phenomenon occurs because electrons jump from your head to the balloon during friction. This way the balloon becomes negatively charged and your head becomes positively charged. The opposite charges then attract each other. This phenomenon is called static electricity.

A honey bee actually does the same thing when they are trying to find food. As she flies from flower to flower, her body hair becomes positively charged. This makes it easier for a flower’s negatively charged nectar to stick to these hairs.

So the bee generates a little bit of static electricity. The phenomenon also occurs in other insects that stay in the air, from butterflies to mosquitoes and grasshoppers. But do they also contribute to the large electric field in the Earth’s atmosphere? The researchers, led by Ellard Hunting, tried to find out.

1000 volts per meter

Jagt and colleagues released a swarm of bees in a certain area. During the 3-minute flight, they measured whether and to what extent the bees changed the atmospheric electric field at the site. The result was clear: the intensity of the electric field was at least 100 volts greater at 1 meter above the ground. That is, the charge difference between the ground and one meter above it was at least 100 volts in the area studied. A passing thunderstorm doesn’t even cause that!

In other insects, such as desert locusts, the change in electric field was estimated from a computer model. A swarm of locusts sometimes assumes biblical proportions: the swarm can cover an area of ​​up to 1000 square kilometers and contain up to 80 million locusts. And it does not go unnoticed, the researchers believe. The insects appear to add 1000 volts per meter to the electric field in the air.

The researchers believe that both the size of the insect swarm and the density (the number of insects per surface) determine how strongly the animals affect the electric field. According to the model, a swarm of grasshoppers scores very highly on both fronts.

Biological factors

Until now, very little was known about the contribution of biological factors to the atmospheric electric field. There are also almost no researchers who specifically deal with the interaction between insects and the atmosphere. Hunting and his team therefore hope that this study will eye opener is for scientists. They say there are many more interesting mysteries to unlock, from the action of microbes in the soil to the movement of electrical charges in the air itself.

“What a fun study!”, replies bee expert Arjen Strijkstra from Van Hall Larenstein University of Applied Sciences. “The measurements seem well done. The relationship between the disturbances in the electric field and the density in the swarm also strikes me as convincing.” To have a point of criticism, Strijkstra mentions that scientists should be more careful in comparing them with other phenomena in the atmosphere. “For example, winds that can move large amounts of desert dust (such as Saharan sand that sometimes falls from the sky here) have a worldwide effect. While the insects only cause local and minor effects in the electric field. For example, I don’t think it’s lightning fast in a swarm of bees!”

Insect expert Alexander Haverkamp from Wageningen University also finds the results of the study interesting. “These researchers have previously researched the electric fields that bees use when searching for nectar. The electric fields they have now found around swarms of these insects could serve as a means of communication during flight.” But Haverkamp is also careful not to simply copy the results. “It is a pity that there are no direct measurements of a locust swarm . As a result, there is still some uncertainty in determining the phenomenon. Future research may change that.”

Sources: iScience, Cell Press via EurekAlert!

Image: Ellard Hunting/CC-BY-SA

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