Ancient parasitic wasps found in fossil fly pupae

Aug. 28 (UPI) -- Scientists have for the first time identified parasites inside ancient fossil fly pupae.

Roughly half of all species on Earth are classified as parasites, but how different parasitic behaviors evolved isn't well understood. The study of parasite evolution and diversification has been hampered by the dearth of parasites in the fossil record.

In a new study, however, published this week in the journal Nature Communications, scientists reported the discovery of 55 cases of parasitation by four extinct wasp species.

The parasitation events were found inside phosphatized fly pupae from the Paleogene, the period spanning 66 million years ago to 23 million years ago. The fossils were sourced from museum collections in Basel and Stockholm. Scientists analyzed the mineralized fly pupae using ultrafast X-ray imaging.

"Our project proves that it is worthwhile to study old collections afresh with latest technology," Thomas van de Kamp, researcher at the Karlsruhe Institute of Technology in Germany, said in a news release.

The high-definition X-ray images allowed scientists to digitally reconstruct the four parasitic wasps. Scientists determined each of the four species revealed by the fossil analysis used a unique parasitic strategy. Researchers classified the four species under the insect order Hymenoptera.

New spectral analysis methods helped scientists more efficiently analyze a large number of tiny fossils.

"Sample throughput is high. Imaging and evaluation of the data take place in a partly automated manner, which makes such measurements feasible," said van de Kamp.

The discovery proves parasitic wasps had evolved a diversity of host adaptation strategies as early as 66 million years ago.

Researchers believe their new fossil imaging and analysis technology will allow scientists to survey larger numbers of small fossils in a shorter amount of time.