Forensically important insects and microbial communities associated with decomposition of above ground cadavers in Southeastern Louisiana

Insect diversity and succession patterns of necrophilous species associated with cadaver decomposition islands (i.e., large vertebrate carcasses above-ground) is well known; however, limited to no information is available regarding microbial diversity and community structure throughout decomposition.  In forensic entomology, entomological information is often collected from carcasses and cadavers recovered above-ground on vegetation or surface soils.  Furthermore, soil microbes could be of particular forensic importance in later stages of decay when insect abundances have declined.

Four 12-month long seasonal studies (winter, summer) were conducted in a woodland habitat in Hammond, LA from February 2011 to August 2013.  Each experiment included three adult swine carcasses (~ 60-160 kg) placed directly on the leaf litter/soil surface.  Sampling protocols varied for insect and soil core collections throughout decomposition, and included manual sampling and pitfall traps for insects and two soil cores collected beneath each carcass per sampling event.  Control soils were collected approximately 15 m from the carcasses.

Predominant calliphorid species collected from the winter carcasses were Calliphora vicina and Phormia regina; while Cochliomyia macellaria and Chrysomya rufifacies were the most abundant species at the summer carcasses.  Hydrotaea leucostoma (Muscidae), Hermetia illucens (Stratiomyidae), and Fannia scalaris (Fannidae) were regularly observed during the advanced stages of decay for all winter and summer carcasses.  Processing of soil samples included: soil characterization, microbial enumeration, DNA extraction, 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.