Microbiome of blow flies (Diptera; Calliphoridae) associated with human cadavers

Flies are important members of the decomposition ecosystem and can be important evidence of death investigations when the time since death is questioned. Because flies arrive during the earliest stages of decomposition and have been recorded colonizing the corpse within minutes of death, they may be significant in establishing a cadaver-specific microbiome. To investigate the biodiversity of the microbiome of blow flies associated with human decomposition, human cadavers were placed outdoors to decompose under natural conditions at the Southeast Texas Applied Forensic Science (STAFS) facility (a willed body facility) at the Center for Biological Field Studies (CBSF), Sam Houston State University, Huntsville, Texas. The first 40 flies visiting the cadavers were collected and submitted to dissection of the tarsi, labellum, and ovipositor. To assess diversity, sample processing, 16S rRNA gene amplification, and Illumina sequencing were performed following protocols benchmarked as part of the Human Microbiome Project. 16s data were processed and analyzed using QIIME version 1.7.0. Samples were grouped according to body site, cadaver of origin, and accumulated degree hours. Special attention is paid to bacteria that have only been recorded in association with blow flies before. Ultimately, bacterial data such as these can be refined to develop a model of microbial succession that can be used to estimate the postmortem interval, or the time since death.