Study Recreates the Calling Sound of a 150-year-old Insect from a Museum Specimen

A doctoral student has led a new research study that reconstructs the song of a 150-year-old insect preserved as a museum specimen at the Natural History Museum in London.

Charlie Woodrow, a PhD student in Zoology from the University of Lincoln, UK, and the investigative team used micro-scanning Laser-Doppler Vibrometry (LDV) to recreate the vibration patterns and resonances of the insect’s sound production organs. They used morphological data to calculate the acoustic signal structure.

Prophalangopsis obscura is an insect belonging to an ancient bush-cricket family of over 100 known species dominant during the Jurassic period, of which only eight members remain alive today. P. obscura is the only species bearing a strong resemblance to the extinct relatives, making it the perfect focus for a study into the fossil species.

Ecological knowledge surrounding the insect is considerably limited due to its uncertain geographical distribution. Moreover, no further male specimens have been discovered in over 150 years while only two potential female specimens have ever been found.

Ed Baker, Bioacoustics Researcher at the UK’s Natural History Museum and co-author of the research paper, said: “Bioacoustics is a rapidly advancing and multi-disciplinary field and this collaboration shows how useful the Museum’s historic collections can be in understanding the behaviour of rare and extinct organisms.

 “The Museum has been working on the bioacoustics of this group of insects since the 1960s, and this work continues with automated acoustic monitoring as part of the new Urban Nature Project.”

Charlie conducted a thorough study of their acoustic capability to unlock greater understanding of the ancient bush-cricket communication systems. The front wings of P. obscura, which like all crickets and katydids are used to produce sound, have the same morphology to many fossil prophalangopsids (a family of insects).

By using knowledge of the wing biomechanics of other extant members of the ancient bush-cricket family, the scientists were able to reconstruct the calling song of P. obscura.

The research was undertaken as part of the ERC-funded project The Insect Cochlea: A Non-invasive Path Towards Enhanced Sound Detectors.

The full research paper has been published in the peer-reviewed open access scientific journal PLOS One. Charlie’s PhD research was supervised by Professor Fernando Montealegre-Zapata, an entomologist specialising in sensory biology at the University of Lincoln, UK, and Principal Investigator on The Insect Cochlea project.

Charlie Woodrow, PhD student in the School of Life Sciences at the University of Lincoln, and lead author on the paper, said: “This study is one I am particularly passionate about as it exemplifies just how much knowledge we have stored in museum collections across the world, and the need to preserve and maintain these collections for novel studies and technologies into the future.

 “I am very grateful to the University of Lincoln for funding my PhD stipend and supporting me with the work carried out in the lab group I am a part of. Graduate students work so hard on these sorts of outputs, often beyond the scope of their projects, and having the appropriate funding to be able to concentrate on such work is what keeps academic research going.”

The key finding is that the P. obscura produces a low-pitch sound at ~ 5 kHz. Low frequency sounds travel very far distances, hence, both P. obscura and the prophalangopsids of the Jurassic could communicate over vast landscapes, indicating reduced pressures from eavesdropping predators.

The conclusions made by the team represent meaningful progress toward rediscovering the species. By deploying autonomous recording units (ARUs) in potential field sites and using signal detection algorithms, Charlie ventures that further specimens of Prophalangopsis obscura can be located and their true song recorded to validate the accuracy of the predictions made in the paper.