Predatory wasps are electrically charged and emit electric fields, and their larvae respond to these fields with defensive behaviour, according to a new study from the University of Bristol.
Sam J. England and Daniel Robert discovered that some terrestrial animals can sense the electric fields emitted by electrostatically charged predators and use this sensation to mount defensive actions. These photos show the four animal species examined in the study: (A) A Cinnabarga larva (Tilia jacobae) Taking a defensive posture. (B) The larva of a rare transpiration moth (Terrorcrus Rekens) in a defensive coiled position. (C) The larva of the European peacock butterfly (Aglais), (D) a predatory common hornet in the middle of a defensive maneuver (HornetImage credit: Sam J. England & Daniel Robert, doi: 10.1073/pnas.2322674121.
“Many animals naturally build up static electricity on their bodies as they move around in their environment, and we knew that static electricity can push or pull on other charged objects,” said researcher Sam England, from the University of Bristol.
“In particular, we knew that insect hairs can be moved by electric fields emitted by electrostatically charged objects, in the same way that an electrically charged balloon can move hair on the head.”
“This got us thinking: What if prey animals like caterpillars could detect predators by sensing the electric fields emitted by the predators?”
“Could the static electricity of a predator like a wasp be enough to alert the caterpillar to the approach of the wasp, by pushing and pulling on the caterpillar's sensory hairs?”
Dr England and his colleague, Professor Daniel Robert, from the University of Bristol, measured how much static electricity the wasps and caterpillars had picked up by passing them through a static sensor.
The researchers then fed these charge values into a computational model to mathematically predict how strong the electric field would be as the wasp approached the larvae on the plant.
When the caterpillars reacted defensively to these conditions, they were able to determine whether it was sensory hairs that were detecting the electricity by using a laser to detect tiny vibrations and measuring how much the hairs moved in response to electric fields of different frequencies.
The results are concerning because they show that the caterpillars are also sensitive to the frequencies of electric fields emitted by power lines and other electronic devices.
This means that humans may be filling the environment with electrical “noise” that interferes with animals' ability to detect predators.
Dr England continued: “We now feel it is extremely urgent to assess whether introducing a new type of sensory pollution – electrical noise – is interfering with the ability of caterpillars, and other animals, to detect predators.”
Almost all terrestrial animals seem to accumulate static electricity, so this static sense may be widespread, and the discovery that static electricity plays a role in these ecological interactions would open up an entirely new dimension to our understanding of how animals sense each other, and more generally, how and why animals evolve in certain ways.
“Our study suggests that terrestrial animals may be able to use static electricity as a predator-detection cue,” Dr England said.
“This is likely an ability that is particularly widespread in insects and small animals such as spiders and scorpions.”
“This study provides the first example of an animal detecting predators by sensing static electricity emitted by the predator.”
“This reveals a new dimension of predator-prey interactions on land, but also suggests a previously unnoticed way in which we may be negatively impacting wildlife by introducing sources of electrosensory pollution.”
of study Published in Proceedings of the National Academy of Sciences.
_____
Sam J. England & Daniel Robert. 2024. Prey can detect predators via airborne electroreception. PNAS 121(23):e2322674121; doi:10.1073/pnas.2322674121
Source: www.sci.news
