D3168: (1st Place) The role of aquatic midges (Diptera: Chironomidae) in carrion decomposition: Forensic applications

In terrestrial ecosystems, the well-documented succession of carrion-colonizing insects, coupled with their developmental timelines, has proven invaluable in forensic science and has been well-studied. Conversely, in aquatic systems, the utilization of insects as indicators during crime scene investigations has been less extensive. Findings from studies on the decomposition of salmon carcasses proposed that chironomids (Diptera: Chironomidae), or non-biting midges, could be a valuable resource in forensic investigations due to their high diversity and functional roles. The present study examined the diversity, abundance, and functional roles of chironomids and other aquatic macroinvertebrates in the decomposition of pig carcasses within pond (N=2) and stream (N=2) ecosystems to better understand how their presence can be used in death scene investigations. Stillborn fetal pigs (N = 6/aquatic system) were caged, fully submerged, and routinely sampled for non-biting midge and other macroinvertebrate diversity and succession over the decomposition process. Physicochemical parameters and stage of decomposition were identified throughout the decomposition process. A significant difference was found when comparing water temperature and carcass mass loss in both pond and stream settings. However, no statistically significant differences were found when comparing other chemical factors in relation to mass loss. The diversity of non-biting midges on carcasses placed into streams (H’=2.01) exceeded that of carcasses in ponds (H’=1.73), while the two systems showed moderate similarity (JSI = 0.50) in terms of genera found on the carcasses. Chironomids may hold significant forensic value when comparing diversity, abundance, and functional roles between aquatic ecosystems.