Wherefore the magic? The evolutionary role of psilocybin in nature
bioRxiv (Cold Spring Harbor Laboratory) December 19, 2025 K.j Matthews Nicholass, I Flis, M.e Hanley et al.
Psilocybin, the psychedelic compound in 'magic' mushrooms, may have evolved as a chemical defense against insects. When fruit fly larvae were exposed to extracts from Psilocybe mushrooms, they showed reduced survival, lower pupation rates, and inhibited locomotion. Adults that developed from exposed larvae had smaller thoraxes and wings, along with increased fluctuating asymmetry, indicating developmental stress. Surprisingly, flies lacking 5HT2A receptors responded the same as normal flies, suggesting psilocybin's effects on insects involve different mechanisms than in vertebrates. DNA analysis showed that Psilocybe semilanceata hosts a distinct invertebrate community compared to most grassland fungi, though it overlapped with the non-psychedelic species Mycena epipterygia. This suggests psilocybin's ecological role may be more complex than simple defense.