Chinese Academy of Sciences researchers report that fossilized entomopathogenic fungi from mid-Cretaceous amber reveal some of the oldest direct evidence of parasitic relationships between fungi and insects, suggesting that Ophiocordyceps fungi originated approximately 133 million years ago and underwent early host shifts that shaped their evolution.

Results indicated that Ophiocordyceps likely emerged during the Early Cretaceous, about 133.25 million years ago, earlier than previously proposed estimates of ~100 million years. Ancestral state reconstructions suggest that the genus initially parasitized beetles before undergoing host shifts to Lepidoptera and Hymenoptera during the Cretaceous. Researchers inferred that these transitions coincided with the diversification of moths and ants, which offered new ecological opportunities for fungal specialization.

The authors concluded that the fossils not only document some of the oldest evidence of insect-pathogenic fungi but also support the view that Ophiocordyceps diversified in tandem with its insect hosts.