Fossils reveal new ancient parasitic wasp species

Avatar By Joseph Scalise | 2 years ago

A group of international paleontologists have uncovered four new ancient parasitic wasp species from fossils found in France, a new study published in Nature Communications reports.

The remains — which date back between 23 and 66 million years —  give researchers the first example of parasitic behavior among wasps in the fossil record. They also show endoparasitism, which is the process where a parasite develops or lives inside its host.

To make the discovery, the team used a new scanning technique known as high-throughput synchrotron X-ray microtomography to look inside 1,510 mineralized fly pupae. Of those, 55 revealed parasitic events.

It is not easy to find parasitic behavior in the fossil record. That is because, not only does the parasite need to be caught in the act of infecting its host, but parasites cannot be seen on the outside of a fossil.

For those reasons, the only parasitic wasps in the fossil record are adults trapped in amber. The new study is the first to show fully developed wasps inside a hosts.

“We used a synchrotron—a type of particle accelerator—to generate intense X-rays in order to perform the high-throughput tomography scanning [cross-sections of solid bodies] of 1,510 samples in the scope of just one week,” lead author Thomas van de Kamp, a researcher from the Karlsruhe Institute of Technology, told Gizmodo. “The study was performed by a highly interdisciplinary team of biologists, paleontologists, physicists, computer scientists, and mathematicians. We employed a sophisticated experimental setup, built and run by physicists and computer scientists, algorithms for image analysis developed and optimized by mathematicians and relied on the expertise of paleontologists and entomologists for the interpretation of our results..”

The fly pupae analyzed in the study date back to the Paleogene period, which began at the end of the Cretaceous. Many of the fossils revealed adult wasps in the act of parasitizing their hosts, and the fact that there were no eggs or larvae suggests those did not survive the fossilization process.

Each of the new wasp species had a life cycle that began with a female wasp laying an egg in a fly pupae. Then, once they hatched, the larvae fed on the still-living fly pupa and then developed into a full grown insect.

The study sheds new light on early wasps and could provide new insights for future studies.

“The detail of preservation of many wasps was just exceptional,” added van der Kamp. “The 3D reconstructions of the tomographic data facilitated species descriptions as done for extant [living] species. We were also surprised how little is still known about the lifestyle of extant parasitic wasps, despite the huge number of species.”