Eukaryotic and Prokaryotic RNAseq of untended mouse carcass samples and mouse carcass samples tended by the beetle Nicrophorus vespilloides.

The ability to feed on a wide range of diets has enabled insects to diversify and colonize specialized niches. Carrion for example, is highly susceptible to microbial decomposers, but is kept palatable several days after an animal's death by carrion feeding insects. Here we show that utilization of carrion by the burying beetle Nicrophorus vespilloides is associated with altering its bacterial and fungal community composition and its prokaryotic and eukaryotic transcriptome, making them distinct from untended (decomposing) carcasses. Beetle-tended carcasses showed no signs of degradation and supported the growth of the beetles' gut microbiota, including the yeast Yarrowia. In contrast, untended carcasses showed visual and olfactory signs of putrefaction and supported the growth of endogenous and soil-originating microbial decomposers. We demonstrate that breeding beetles preserve carrion by preventing the microbial succession associated with carrion decomposition, thereby resulting in the reduction of putrescine and cadaverine (toxic polyamines associated with putrefaction), and altering the protease, lipase and free amino acid levels, thus ensuring a high quality resource for their developing larvae. Beetle-tended carcasses develop a biofilm-like matrix housing the yeast, which when experimentally removed leads to reduced larval growth. Thus, tended carcasses hosted a mutualistic microbial community that is required for optimal larval growth, likely through symbiont-mediated extra-intestinal digestion and detoxification of carrion nutrients. The adaptive preservation of carrion coordinated by the beetles and their symbionts demonstrates a specialized resource management strategy through which insects modify their habitats to enhance fitness.