Graz researchers reconstruct songs of 165-million-year-old insects

Researchers at the University of Graz have reconstructed the mating calls of insects that lived 165 million years ago, using 20 fossils from Inner Mongolia, China, ORF reported. The study found that some of the insects communicated at ultrasonic frequencies.

Male crickets, grasshoppers and cicadas use sounds to attract females. Their calls are generally produced by rubbing a hardened edge on one forewing against a row of fine teeth on the underside of the other. Structures in the wing surface amplify the resulting vibrations, effectively acting as small loudspeakers.

Because these sound-producing structures are preserved well in fossils, the researchers were able to examine the acoustic past. Thorin Jonsson from the University of Graz’s Institute of Biology used interdisciplinary methods to study the insects’ wing structures, mechanics and sound-producing and sound-receiving functions.

Jonsson and colleagues from universities in Lincoln, Bristol, Beijing and Tempe analysed fossils from nine grasshopper species that lived during the Middle Jurassic. Using analyses, simulations and artificial intelligence-supported evaluations, they reconstructed the pitch and basic syllables of the insects’ mating calls.

The results showed a wide range of call frequencies. Several species produced pure, low tones resembling those of modern crickets, while others generated higher frequencies similar to those of present-day leafhoppers.

One species called at frequencies above 20 kilohertz, indicating that ultrasonic communication among insects was established long before bats appeared in the Eocene, the researchers said. Their findings were published in the latest issue of the scientific journal PNAS.