Carcass concealment alters assemblages and reproduction of forensically important beetles

Abstract

Most forensic studies have examined decomposition and insect colonization for estimating the minimum postmortem interval (PMImin) using carcasses that are readily accessible to insects but in homicides, cadavers are often concealed to a certain extent. Here, we tested the hypothesis that the type of concealment of a decomposing resource and the permeability of the material used affect to different extents the animals attracted to the resource. To this end, beetle assemblages were documented for 100days on 15 domestic pig carcasses, placed individually in soft shell suitcases, trashcans with a hinged lid, and sealable drums in an untended open field in New Brunswick, Canada. Five pigs were allocated to each treatment. During the study, almost 33,000 beetle occurrences from 50 recognizable taxonomic units were documented around containers that concealed carcasses. Results indicated that trashcans, drums, and suitcases had different effects on the patterns of beetle arrival and departure from the vicinity of concealed carcasses, on beetle assembly, on their breeding strategies, as well as on the interspecific relationships between beetles of forensic importance. Of the 50 recognizable taxonomic units, only six species exhibited a somewhat predictable occurrence and yielded information about the time of placement or the type of container. Results also suggested that some of the abundant Silphidae species opted to breed or feed in suboptimal conditions or at a later period to avoid competing with the dominant silphid Necrodes surinamensis (Fabr.). This suggests the occurrence of preferential colonization and/or asymmetrical competition between beetle species, which would affect the potential of these species for PMImin estimations on concealed carcasses.