The fossilized bacteria from Cachin Amber in Central Cretaceous belong to the same family as the zombie ant bacteria, ophiocordyceps unilateralis, which has become well-known as the inspiration for various popular apocalyptic video games and TV series, such as Our Last.
Ecological reconstruction of Cretaceous insects and insect pathogenic fungi. The ants have abandoned the infected PUP, and the infected fly is located on the trunk of a distant tree. Image credit: Zhuang et al., doi: 10.1098/rspb.2025.0407.
Two newly identified species, Paleoophiocordyceps gerontoformicae and Paleoophiocordyceps Ironomyiae, represent some of the oldest fossil records of animals and pathogenic fungi.
These specimens were discovered in 99-million-year-old fragments of Kachin amber, sourced from a mine near the village of Neuebham in northern Myanmar.
“Insects and fungi are among the most diverse groups of living organisms, cohabiting Earth’s ecosystems for over 400 million years,” explains Professor Edmund Jalsenbowski, a paleontologist at the Geology, Paleontology and Natural History Museum in London, along with his colleagues from the Nanjing Institute of Studies.
“Consequently, they have developed intricate and close ecological relationships, including reciprocity, predation, and parasitism.”
“Entomopathogenic fungi, in particular, have garnered attention for their role in regulating insect populations, though much remains unclear about them.”
“The infection process begins when spores come into contact with the proper host, initiating germination through enzymatic hydrolysis, allowing entry into the insect’s body cavity (hemocoel).”
“Once the fungus infiltrates the insect’s body, it (as yeast-like cells at this phase) proliferates via budding, consuming the host’s body from within.”
“Eventually, the host typically succumbs to fungal toxins, leading to the formation of chains of yeast-like cells that transition to the filamentous stage shortly after the host’s death.”
“These filaments gradually organize into compact spore-producing structures (sporocaps) that emerge from the softer parts of the insect, dispersing spores into the environment to infect additional hosts.”
Holotype of Paleoophiocordyceps Ironomyiae. This comparison of mid-Cretaceous specimens shows similarities with existing Bacillus ophiocordis: (a, b) Lateral and dorsal views of the bipteran host, where potential fungal structures are visible. (c) Closure of the fungal stroma of Paleoophiocordyceps Ironomyiae; (D, E) Apex of the fungal stroma. The red arrows indicate the surroundings. (f, g, h) Presence of ophiocordyceps stromas for Ant and Dipteran hosts. Scale bars – 0.5 mm (a, b), 0.1 mm (c) and 50 μm (d, e). Image credit: Zhuang et al., doi: 10.1098/rspb.2025.0407.
According to the authors, Paleoophiocordyceps gerontoformicae was found in a young ant, while Paleoophiocordyceps Ironomyiae was discovered on a fly.
“It’s captivating to observe that some of the unusual phenomena we witness today were also present during the age of dinosaurs,” remarked Professor Jarzembowski.
“Known as a zombie fungus, it can influence the behavior of its host, a feature that has been depicted in popular apocalyptic video games and series like Our Last.”
“Given that the infection is lethal, ophiocordyceps and its fossil counterparts likely played a significant role in regulating insect populations during the Middle Cretaceous, similar to how their modern relatives do today.”
“While parasitism is common in today’s ecosystems, evidence of these interactions is seldom found in the fossil record.”
“This is primarily due to the poor preservation of their soft tissues in fossils and the fact that they reside within their hosts, making identification among insect remains challenging.”
“While ancient parasite specimens have been uncovered, our understanding of their evolution remains limited.”
“This new discovery provides rare insight into these parasites from a long-ago era.”
The team’s research paper was published in the June 2025 issue of Proceedings of the Royal Society B: Biology.
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Yuhui Zhuang et al. Cretaceous insect pathogenic fungi illuminate the early evolution of insect-fungal associations. Proc. R. Soc. B 292 (2048): 20250407; doi: 10.1098/rspb.2025.0407
Source: www.sci.news
