Caterpillars detect the electric fields of hungry wasps

Caterpillars detect the electric fields of hungry wasps

By Gennaro Toma

Some animals have developed the ability to sense the invisible electric fields that permeate all around us. This seemingly foreign force is well known as electroreception in aquatic animals, but has not been observed much on land. Now, researchers have revealed that caterpillars can sense the electrostatic field of an approaching wasp – the first predator-prey interaction ever recorded on land.

Scientists first discovered the phenomenon by measuring the static electricity of the larvae and their predators, common hornets. Proceedings of the National Academy of SciencesThe researchers used electrodes to replicate the electric field created by a wasp approaching a caterpillar, and then exposed three different kinds of caterpillar to the “fake wasps.” Tilia jacobae, Here is a photo.

All species responded with defensive behaviour: two species stayed coiled up for longer protection, while a third bravely fought back by trying to bite the electrodes. The caterpillars responded more strongly when the electric field oscillated at the frequency of a wasp’s wingbeats. The researchers concluded that the caterpillars sense these electric fields with setal fibres covering their bodies that vibrate with electrical stimulation.

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In terrestrial animals that share this sense, “it’s used in conjunction with other senses, like hearing and sight, to basically provide an even more reliable sensory picture of whether and where a predator is present,” says study co-author Sam J. England, a sensory ecologist at the Natural History Museum Berlin.

Gerhard von der Emde, a neuroethologist at the University of Bonn, says the study “provides a very convincing picture of the behavioral response to electroreception in arthropods.” He says he would like to study this behavior in the wild, without artificial electric fields, although he acknowledges it will be difficult.

Neuroethologist Pauline N. Fleischmann of the Carl von Ossietzky University in Oldenberg, Germany, says the study is a great example of “the amazing variety of cues that animals, in contrast to humans, can sense and actually use in their everyday tasks.” She adds that “the most interesting follow-up question is how the wasps try to hide their attacks and how the evolutionary arms race between predator and prey continues.”