Insect swarms can generate as much static electricity as a storm cloud
Insects have been known to sense and tap into electric fields, but new research shows that swarms can actually produce atmospheric electric charges. By measuring the extent of this influence, the scientists found that large swarms could produce as much charge as a storm cloud.
Bees have a more intimate relationship with electricity than you might expect. They sense changes in electric fields to navigate to flowers. Static charges play a role in helping pollen stick to them. And they can gain an electric charge as they fly through the air. But what influence bees may have on the atmospheric electric charge hadn’t been investigated.
“We always looked at how physics influenced biology, but at some point, we realized that biology might also be influencing physics,” said Ellard Hunting, first author of the new study. “We’re interested in how different organisms use the static electric fields that are virtually everywhere in the environment.”
So, researchers at the University of Bristol and University of Reading measured the electric fields near swarming honeybees. The team placed an electric field monitor near research hives and measured changes when swarming behavior began. And sure enough, swarming honeybees raised the atmospheric electricity by between 100 and 1,000 volts per meter, depending on the density of the insects within the swarm.
From this starting point, the team then developed a model that could extrapolate the influence of other swarming insects on the atmospheric electric charge. Locusts were found to have the most substantial impact, because they can swarm at incredible, “biblical” scales. The researchers measured their charge, and combined it with records of their densities while swarming, and found that they can produce similar atmospheric electric charges as a storm cloud.
The team says that the influence of swarming insects on the atmospheric electric field is a factor that’s currently overlooked in climate and weather models. It also suggests that other organisms, like birds and microbes, might have similar effects.
The research was published in the journal iScience.
Sources: University of Bristol, Scimex
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Amateur experimenters can easily construct very sensitive electrometers for such research using a cheap op-amp with a very low input bias current (as low as femtoamperes). These are available from firms such as Texas Instruments (TI) for a few cents to a few dollars (their LMC6001 is likely the best choice for experimenters). It's a bit involved to explain here, but it's about the simplest possible op-amp circuit: an impedance converter formed by connecting the output to the inverting (-) input. The other input pin is bent away from the chip and is used as an electrical field antenna. Use a "split power supply" (a pair of batteries) so the inputs are centered around zero volts. The output can go to a voltmeter or to a scope to graph the ambient electrical field voltage (USB oscilloscopes are quite affordable). This setup can detect the movement of a cat on the other side of a room. It also picks up the field from power lines, though, so filtering the output with a notch filter (e.g. twin-T type) to take out the 50 or 60Hz interference makes the output much nicer. This circuit was the core of a fun science fair project I helped a 10 year-old with some years ago. It reveals a whole invisible world.