Alternatively, they can originate from symbionts, such as antibiotic-producing bacteria present in fungus-farming ants that defend mycelia of the cultivated fungus 9. These strategies may originate from the insect, such as venom peptides in parasitoid wasps and hydrophobic secretions in beewolf wasps that preserve paralysed prey 7, 8.
These foods may also be provisioned to their offspring through mass provisioning or progressive provisioning, requiring specialized behavioural and chemical strategies to prolong food availability, and may be associated with the evolution of parental care 6. Insects feed on an extraordinary range of resources, some of which are highly unusual and challenging to consume. This is also true for insects, where ancient associations with microorganisms have enabled the colonization of novel niches by exploiting unusual diets and overcoming host defences 1, 2, 3, 4, 5. Among these, the association between an animal host and its microbiota is increasingly recognized to fundamentally affect animal life by shaping host behaviour, development, immunity and metabolic homeostasis 1. Species may respond to selection pressures arising from such interactions by combating antagonistic members, or forming mutualistic associations with others. Interspecific interactions have important implications in shaping the dynamics of biological communities on ecological and evolutionary timescales. Our results provide evidence of potential metabolic cooperation between the host and its microbiota for digestion, detoxification and defence that extends from the beetle’s gut to its nutritional resource. A distinct microbial community composed of Firmicutes, Proteobacteria and a clade of ascomycetous yeasts (genus Yarrowia) is present in larval and adult guts, and is transmitted to the carcass via anal secretions, where the yeasts express extracellular digestive enzymes and produce antimicrobial compounds. We find a strict functional compartmentalization of the gut involving differential expression of immune effectors (antimicrobial peptides and lysozymes), as well as digestive and detoxifying enzymes. We characterize gene expression and microbiota composition in the gut, anal secretions, and on carcasses used by the beetles. Here we use burying beetles ( Nicrophorus vespilloides), which feed their offspring on vertebrate carrion, to investigate the digestive and defensive basis of carrion utilization. Insects that use ephemeral resources must rapidly digest nutrients and simultaneously protect them from competitors.
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