Microbial and insect communities associated with cadaver decomposition islands in Louisiana

Microbial communities within topsoil and forensically important insects are both key factors in the decomposition of large vertebrates. Currently, there is limited information available regarding the microbial communities associated with the decomposition of large vertebrates above-ground (i.e., cadaver decomposition islands). Most studies regarding microbial diversity and community structure are associated with profiling soil microbial populations, clandestine graves, or small-scale laboratory studies. However, the majority of decomposing remains of forensic interest (humans and poached wildlife) are recovered above-ground. Furthermore, soil microbes could be of particular forensic importance in later stages of decay when insect abundances have declined. This study includes four series of experiments conducted in a woodland habitat in Hammond, LA during the winter and summer seasons from 2010-13. The primary goals of this research are two-fold: 1) to establish microbial diversity, community structure, and succession patterns of soil microbes associated with swine carcasses; and 2) to correlate the microbial soil profiles with the observed stages of decay and faunal succession patterns of necrophilous insects. Each seasonal experiment consisted of three adult swine carcasses (~ 60-160 kg) placed directly on the leaf litter/soil surface. Processing of soil samples included: soil characterization, microbial enumeration, DNA extraction and purification, PCR amplification, T-RFLP analysis, and sequencing analysis. Data generated from this study will produce successional patterns of insects and microbes which potentially could elucidate estimations of time since death for large vertebrate carcasses above-ground. Data from the winter 2011 study (5 February to 6 December 2011) will be presented.