Natural and anthropogenic changes in the insect fauna associated with carcasses in the North American Maritime lowlands.

The insect pool available for carrion visitation and colonisation varies with geographical areas, hence the need to build a comprehensive database wherever such data could be used in forensic investigations. However, most of the geographic records on carrion-related insects are from short-term seasonal studies. Here, we provide the year-round taxonomic composition for the dominant ecosystem of the Maritime lowland ecological region that borders the Gulf of St. Lawrence, Canada, and we examine how this composition is subjected to natural (seasonal) as well as anthropogenic changes. Fresh pig carcasses, used here as human surrogates, were exposed recurrently throughout the whole annual period when carrion-related insects are active in forests and adjacent areas subjected to human-induced land cover changes from agricultural practices. A total of 130 necrophageous and predacious insect species representing 2 orders, 18 families and 75 genera were recovered from carcasses. Abundant fly species were able to visit and/or colonise carcasses exposed in both forests and agricultural fields but the species involved varied throughout the year. Conversely, the complex of abundant coleopterans found on carcasses remained stable throughout the year but differed between forests and agricultural fields. Considering the seasonal and anthropogenic changes that were observed in the complex of carrion-related insects, we stressed that inference on the taxonomic composition in relation to minimum postmortem interval should be restricted to a specific habitat and time of the year. These results also have methodological implications, suggesting that the experimental designs of forensic studies in temperate areas require adjustments to permit robust estimations of minimum postmortem intervals from the insect fauna associated with carcasses.