Prehistoric spider wasp discovered in amber

Breaking new ground 14. jan 2024 3 min Postdoctoral Fellow Evgeny Perkovsky Written by Kristian Sjøgren

Scientists have identified a new species of spider wasp in a lump of amber millions of years old. A researcher says that new insect species are found in amber almost every day, providing information about insects’ evolution and the climate in both the past and the present.

Old lumps of amber can provide insight into prehistory and the organisms living there. Every day researchers find lumps of amber with “new” species of insects that have been extinct for millions of years.

In one such lump from Rovno, Ukraine, researchers just identified a species of spider wasp that has been extinct for millions of years.

Although the species has long been extinct, finding it provides insight into the evolutionary development of this group of insects that still has living relatives today.

“Fossil insects differ from living insects, especially older ones. They can therefore provide valuable knowledge about how insects have evolved. They may also have lived in areas where they are absent today, which can provide knowledge about how, for example, landscape or climate has changed over time,” explains a researcher behind the study, Evgeny Perkovsky, Postdoctoral Fellow, Natural History Museum of Denmark, University of Copenhagen.

The research has been published in Zootaxa.

Vast experience required to determine the sex of fossil insects

In the amber lump from Rovno, the researchers characterised Paleogenia waichertae, the name given to the extinct species of spider wasp from the genus Paleogenia.

P. waichertae is small: 3.2–3.8 mm. It differs from other extinct species of spider wasps by having a differently shaped body and antennae.

P. waichertae is also the 26th species of extinct spider wasp identified in lumps of amber and the first found in an amber lump from Ukraine, and it has living relatives in both the United States and Asia.

Evgeny Perkovsky says that determining the age of species of insects found in amber can be difficult because they lack a prehistoric context but that the amber lumps from Rovno are probably the same age of about 35–37 million years as other amber lumps found in the Baltic area.

Further, characterising an insect that has been encased in amber for millions of years is not always easy.

However, the researchers were even able to determine the sex of the specimen of P. waichertae.

“This requires sophisticated technologies and at least 10 but preferably 20 years of experience in describing fossil insects, because they are often not in the best condition. In addition to characterising them from lumps of amber, we can also do this from finds in moler, which is marine Eocene diatomite interbedded with grey to black layers of volcanic ash that is present in parts of Denmark. From lumps of amber, we characterised 10 extinct species of parasitic wasps at the Natural History Museum of Denmark last year, and in November and December we characterised an extinct parasitic wasp from the moler and an extinct species of cockroach,” says Evgeny Perkovsky.

He elaborates that because the insects are so old, DNA cannot be extracted from them. Their species can only be determined based on their form and structure.

Fossil insects are like jigsaw puzzle pieces

Determining more and more extinct insect species is enabling researchers to map the evolutionary development of insects.

Each insect fossil is a jigsaw puzzle piece in the overall understanding of why today’s insects look the way they do and how they evolved to become what they are today.

Comparisons between the spider wasps of today and the past can help to determine when they emerged as a genus, and discoveries in lumps of amber, moler and other material can help to determine where they lived and how they have spread over time.

“Based on discoveries in amber, we can also learn more about how different species have interacted and what the world in which the insects lived looked like,” explains Evgeny Perkovsky.

He elaborates that the climate in which P. waichertae lived was probably very different from today’s climate. However, determining what the climate was like requires characterising more than one species.

“Many insects require frost-free winters, which is why spider wasps only live in tropical regions today. But ancient insect discoveries in amber show that the climate in the Northern Hemisphere probably included warmer winters and cooler summers,” he adds.

Northern Jylland is perfect for studying fossil insects

Through more than 500 published articles on extinct insect species, Evgeny Perkovsky and colleagues have made several other interesting discoveries. They have identified an extinct species of the order Mantophasmatodea, a wingless insect.

In fact, the researchers first identified the species in an ancient lump of amber, but it was found alive in South Africa the following year. It had been known for 100 years, but researchers had classified it as an immature walking stick insect.

Evgeny Perkovsky says that studying fossil insects can also help in understanding how global warming will affect insects in the future.

“In northern Jutland, we can study insects in moler from one of the greatest warming periods within the last several million years and also study insects in amber from the most important global cooling period that happened afterwards. This can improve knowledge on how the climate has changed in the past and how climate change can affect insects and other life today,” he concludes.

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