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Abstract:
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 the burying beetle Nicrophorus vespilloides preserves
carrion by preventing the microbial succession associated with carrion
decomposition, thus ensuring a high-quality resource for their
developing larvae. Beetle-tended carcasses showed no signs of degradation
and hosted a microbial community containing the beetles’
gut microbiota, including the yeast Yarrowia. In contrast, untended
carcasses showed visual and olfactory signs of putrefaction, and their
microbial community consisted of endogenous and soil-originating
microbial decomposers. This regulation of the carcass’ bacterial and
fungal community and transcriptomic profile was associated with
lower concentrations of putrescine and cadaverine (toxic polyamines
associated with carcass putrefaction) and altered levels of proteases,
lipases, and free amino acids. 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 promotes optimal
larval development, likely through symbiont-mediated extraintestinal
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.
