Fig. 2

a Area of mycelial growth on the corpse placed on different nest materials. “Fresh” refers to untreated nest material; "Dry-heated" refers to nest material treated with dry heat (100 °C, atmospheric pressure); and “Autoclaved” refers to nest material subjected to autoclaving (120 °C, 2 atm). Significant mycelial growth was observed in the autoclaved treatment compared to both the fresh and dry-heated treatments. Different letters indicate significant differences in mycelial growth area among treatments (ANOVA, Tukey’s HSD test, α = 0.05). b Procedure for isolating actinobacteria from nest materials. c Phylogenetic tree of isolated actinomycetes, showing high sequence similarity (> 99%) to Streptomyces murinus. d Absolute abundance of Streptomyces actinomycetes in nest material, expressed per unit weight, and estimated by qPCR targeting the 16S rRNA gene. In the "with-corpse" treatment, pathogen-infected corpses were buried in the nest material, while in the "without-corpse" treatment, only nest material was used. Significant increases in Streptomyces abundance were observed on day 10 in the with-corpse treatment compared to the without-corpse treatment (GLMM, likelihood ratio test, **P < 0.01). e Relative ratio of growth-inhibited fungal spores based on absorbance (595 nm) in both with and without corpse treatments across three time points (day 1, 5 and 10). To eliminate the contribution of Streptomyces cells or growth to turbidity, nest material extracts were filtered through a 0.22 µm membrane before mixing with Metarhizium anisopliae spore suspensions. On days 5 and 10, the ratio of growth-inhibited spores was significantly higher in the with-corpse treatment compared to the without-corpse treatment (GLMM, likelihood ratio test, **P < 0.01, ***P < 0.001, n.s. = not significant).