A study conducted by scientists at the University of Bristol has found that caterpillars respond defensively to electric fields similar to those emitted by their natural predators. The study, published in the journal PNAS, revealed that caterpillar hairs move in response to electric fields and are most sensitive to the frequencies corresponding to the wingbeats of other insects. This suggests that caterpillars’ hairs could be tuned to pick up the electrical cues of their predators, making this the first example of static electricity being used as a sensory cue in a predator-prey interaction.
Lead author Dr. Sam England explained that animals naturally accumulate static electricity on their bodies as they move around their environment, and the hairs of insects can be moved around by the electric field emitted from statically charged objects, similar to how a charged-up balloon can move hair around on a head. The research team measured the static charge carried by wasps and caterpillars and used computational models to predict how strong the electric field would be when a wasp approaches a caterpillar on a plant. They found that caterpillars responded defensively to these conditions and used a laser to detect tiny vibrations to investigate whether sensory hairs were detecting the electricity by measuring how much they move in response to different frequencies of the electric field.
The study’s results are concerning because they indicate that caterpillars are also sensitive to the frequencies of electric fields emitted by powerlines and other electronic equipment. This suggests that human activities may be hindering the ability of animals to detect their predators by creating electrical ‘noise’ in the environment. Dr. England emphasized the urgency of assessing whether electrical noise is impacting animals’ ability to detect predators and suggested that introducing electrical sensory pollution could negatively impact wildlife. Predator-prey interactions are crucial for the survival of animals and are one of the main drivers of evolution on Earth.
Almost all animals on land appear to accumulate static charge, indicating that the ability to sense static electricity may be widespread among terrestrial animals. The discovery that static electricity plays a role in ecological interactions opens up new dimensions to understanding how animals sense each other and evolve in certain ways. Dr. England highlighted that terrestrial animals, especially insects, spiders, and scorpions, may use static electricity as a predator detection cue. This study presents the first example of an animal detecting its predators by sensing the static electricity emitted by the predator, revealing a new dimension to predator-prey interactions on land and pointing to a way in which humans may negatively impact wildlife by introducing sources of electrical sensory pollution.