The Dynamic Maggot Mass Microbiome

Abstract

Necrophagous insect studies have shown that decomposing vertebrate remains are an important ephemeral resource within an ecosystem. However, the microbes (e.g., bacteria and archaea) that were a part of the once living organism and the exogenous taxa that colonize this postmortem resource remain largely underexplored. Also, it is not well understood how these two kingdoms interact to recycle decaying biomass, an important mechanistic question for ecosystem function ecology. To better understand microbial community dynamics throughout decomposition, we used swine carcasses (N = 6) as models for mammalian postmortem decomposition to characterize epinecrotic microbial communities from: the abdominal skin of replicate carcasses; the internal microbiome of individual necrophagous dipteran larvae (maggots); and the microbiome of dipteran larval masses that had colonized the carcasses. Sampling occurred every 12 h for the duration of the decomposition process. We characterized these microbial communities over time using high-throughput 16S amplicon sequencing. The relative abundance of microbial taxa changed over decomposition as well as across sampling locations, suggesting significant interactions between the environment, microbes, and insect larvae. Maggot masses were represented by multiple blow fly species in each mass: Phormia regina (Meigen), Lucilia coeruleiviridis (Macquart), and Cochliomyia macellaria(F.). Relative abundance of these species within the mass also changed as decomposition progressed, suggesting the presence of certain Calliphoridae species within a mass may be associated with temporal shifts of the microbial communities. These results provide new insight into the community ecology of carrion decomposition by providing new data on interactions of microbes and dipteran larvae over time.