A research team led by Karlsruhe Institute of Technology scientist Thomas van de Kamp has found ancient parasitoid wasps lurking inside 55 mineralized fly pupae from the Paleogene period (66-23 million years ago).

“Parasitic lifestyles are extremely successful among animals and evolved independently, perhaps hundreds of times,” Dr. van de Kamp and co-authors said.

“With an estimated 50% of species, parasites comprise a huge proportion of animal life on Earth, and the arms races between parasites and their hosts are considered major driving forces for evolution.”

“In insects, parasitism is especially diverse in the order Hymenoptera, where many wasp species develop as parasitoids on or within an arthropod host.”

“The fossil record of parasitoid wasps is nearly exclusively restricted to isolated adults, with few examples of unidentified larvae trapped in amber next to their hosts.”

Using synchrotron-based X-ray microtomography, the team examined 1,510 phosphatized fly pupae from the Paleogene period of France.

“The fossils we studied belong to the collections of the Natural History Museum of Basel and the Swedish Museum of Natural History,” the researchers said.

“They were collected in the phosphorite mines of the Paleogene fissure fillings of the Quercy region in south-central France in the late 19th century, but the exact locality, collection date and the original collector are unknown.”

“In 1944, Swiss entomologist Eduard Handschin described these fossils in detail and emphasized the value of the externally inconspicuous pieces of merely 3 mm in length. Still, they have fallen into oblivion for more than 70 years. At that time, Handschin had suspected the contours of a parasitic wasp in a thin section of a probably 34 to 40-million-year-old fly pupa, but could not prove it.”

In total, the scientists identified 55 parasitation events by four previously unknown ancient species of parasitoid wasps: Xenomorphia resurrecta, Xenomorphia handschini, Coptera anka and Palaeortona quercyensis.

“These wasps belong to the single family Diapriidae,” they said.

“The most common species was Xenomorphia resurrecta, of which we found 18 females and 24 males, followed by Xenomorphia handschini with one female, four males and one pupa and Coptera anka with three females and one male. Palaeortona quercyensis was represented by one female only.”

“Each of the four parasitic wasp species had its own strategy for adaptation to the host.”

The findings are published in the journal Nature Communications.

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Thomas van de Kamp et al. 2018. Parasitoid biology preserved in mineralized fossils. Nature Communications 9, article number: 3325; doi: 10.1038/s41467-018-05654-y