Fungus Gnat Buried in 40-Million-Year-Old Piece of Amber Is a Rare Gem

The discovery of an amber specimen by a Danish collector in the 1960s on a wild North Sea coast has proved to be of considerable and surprising importance. After carefully examining the approximately 40 million-year-old piece of amber, researchers at the University of Copenhagen discovered that it contained the first fossil of a predatory fungus gnat belonging to a rare genus. This research provides new insights into the distribution of the fungus gnat species and biodiversity in space and time.

The research is published in the journal Scientific reports.

Are you tired of summer invasions of fruit flies, gnats, mosquitoes and other small winged insects? If so, be glad you didn’t experience this 40 million years ago. Back then, Europe’s climate was warmer and wetter, which provided favorable conditions for gnats and other insects.

One of these midges, which died after being trapped in a piece of pine resin, has allowed researchers at the Natural History Museum of Denmark to add a new species of prehistoric midge to their insect family. This first fossil of a rare and never-studied species of midge, Robsonomyia henningseni, was discovered in a piece of Baltic amber along the Danish North Sea coast in the 1960s.

For decades, the piece was hidden in the museum’s amber collection, which numbers 70,000 pieces. Recently, it was extracted from the drawers and subjected to a thorough examination by a team of Polish entomologists. Insect specialists were able to identify the midge as an extinct species belonging to a rare genus of predatory midges. Today, living species of this genus are found only in Hokkaido, Japan and California.

“This is the first time that a fossil of a midge of this genus has been found, which was thought to live only in Japan and North America. This discovery shows that this type of midge was also widespread in Europe in past climates and gives us new knowledge about the distribution of this type of midge on Earth,” says Alicja Pełczyńska, a doctoral student at the University of Łódź and the University of Copenhagen, who described the midge.

Researchers believe the ancient midge is a kind of “missing link” that connects its two rare, living relatives in Japan and the United States. The terrestrial distance between the living species has puzzled researchers, but the new fossil shows that the species’ path may have crossed the European continent.

“Until now, the distribution of this genus of midge has been strange, with thousands of kilometres between species. So it makes sense that it was found in Europe, which is roughly halfway between Japan and North America,” Pełczyńska says.

CV Henningsen, Danish amber collector and mosquito namesake

To learn more about the midge buried in amber, the researchers began by polishing the piece of ocean- and sun-covered amber until it was shiny and transparent.

Once the amber was clear, they used a state-of-the-art camera and spectrometer to take a chemical fingerprint of the amber. This confirmed that the piece was from Baltic amber. They then examined the fossil and determined the species of insect. This part of the process was done by closely studying the male genitalia, which often have varying identifying characteristics.

“The insects mate end to end, which places certain demands on their genitals. The male has appendages, or pincers, next to the penis, which he uses to grasp the female midge during mating. We used the shape of these pincers to identify her,” says Lars Vilhelmsen, associate professor and curator at the Natural History Museum of Denmark.

Based on the results of the analysis, the researchers estimate that the midge lived in the vast pine forests of what we know today as Scandinavia about 35 to 40 million years ago. It became trapped in a piece of resin on a tree, which rivers, sea currents and glaciers of the last ice age carried to the North Sea.

“An amber collector named CV Henningsen found this piece of amber on the west coast of Jutland in the 1960s. Henningsen sold the piece, along with the rest of his collection, to the Natural History Museum of Denmark. Since the species of midge had never been described before, we named it after him, and it is now known as Robsonomyia henningseni,” Vilhelmsen explains.

Unlike Jurassic Park, there is no DNA

Amber is a unique natural time capsule for scientists. Its protective coating preserves the remains of ancient insects and plants, allowing us to learn more about what the Earth looked like 230 million years ago. But if you free it from its amber casing, the insect disappears.

According to Vilhelmsen, there is no blood or DNA to be sucked out of gnats to reanimate them in any way, as is done in the Jurassic Park movies.

“Almost all of the midge’s organic matter has long since decomposed, leaving it a hollow shell. If you try to remove it from the amber, it crumbles. So the best thing to do is to study it inside the amber. Insects trapped in amber can be studied almost as precisely as their living relatives using microCT scanners,” says Vilhelmsen.

The new discovery of the midge fossil provides researchers with new insights into the general migrations of midges across the Earth and contributes to a broader view of biodiversity through time.