The reporter learned from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences that an international paleontological team led by the institute recently discovered two fossils of nematodes parasitic on insects - Cordyceps elegans and Cordyceps taensis in Kachin amber from Myanmar about 100 million years ago. This new discovery provides important evidence for exploring the co-evolution of fungi and insects. In addition, this study pushed back the origin of Cordyceps by about 30 million years compared with previous research.
Light microscopy image of Cordyceps archaea. (Photo courtesy of the research team)
Wang Bo, a researcher at the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences who led the research, said that Cordyceps is a collective name for a type of parasitic fungi. my country's precious Chinese medicinal material "Cordyceps Sinensis" is a member of the Cordyceps family, and its scientific name is "Chinese Cordyceps". In winter, fungal spores invade the body of an insect larvae, absorb nutrients and grow into mycelium, and the larvae become "winter insects"; in summer, the fungus emerges from the insect body and grows a rod-shaped reproductive structure fruiting body, which looks like grass, hence the name "summer grass". The entire Cordyceps family has more than 300 species. They are highly capable and can parasitize a variety of arthropods such as ants, flies, beetles, and spiders, forming various "cordyceps". They can be called "masters of puppet control" in nature. However, because fungi lack hard structures and are highly perishable, there has been little fossil evidence of nematodes, and little is known about their origins and evolution.
Light microscopy image of Cordyceps sinensis. (Photo courtesy of the research team)
The two newly discovered Cordyceps fossils - Cordyceps archaea and Cordyceps taphii - completely preserve the morphological structure of the fungi and can be directly compared with living species. With the help of high-resolution analysis methods such as micro-CT, researchers found that Cordyceps sinensis parasitizes the ant pupae of a type of primitive ant and develops from the opening of the ant's metathoracic lateral plate gland. Its external shape is close to the living Cordyceps unilateralis complex, and its internal structure is very close to the branch of the living Cordyceps sinensis. Another specimen, Cordyceps sinensis, was parasitic on insects of the family Cordyceps in the Cretaceous. Its fruiting body is club-shaped and grows from the joint between the head and neck of the fly. Its shape and growth position are also close to the branches of the extant Cordyceps sinensis.
Paleoecological reconstruction of ants, flies and ancient nematodes during the Cretaceous period. (Photo provided by Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and drawn by Yang Dinghua)
The researchers also collected and sorted the genetic data of 120 living cordyceps, and used new fossils as calibration points to reconstruct the phylogenetic relationships of various groups within cordyceps and correct their origin time. "The results show that the origin of Cordyceps should be in the early Cretaceous period about 130 million years ago, which is about 30 million years earlier than previous research." Wang Bo said.
The relevant research results were published online in the Proceedings of the Royal Society B: Biological Sciences on June 11.