Influence of carcass mass on decomposition rate: A medico-legal entomology perspective

Body decomposition is influenced by various factors, including temperature, rainfall, body mass, and the activities of insects and carnivores in areas where carcasses are abandoned. However, the specific impact of carcass mass on the decomposition rate remains unclear. Therefore, this study aimed to compare the effects of carcass mass on decomposition rate with controlled domestic environmental conditions. Carcasses were categorized as small and large. Decomposition patterns were evaluated using a visual scatterplot to illustrate the relationship between total body scores and log accumulated degree days (ADD). To quantitatively compare decomposition rates, a linear regression model was employed to analyze differences between the two carcass groups. Regardless of carcass mass, a similar oviposition period for flies (Diptera) was observed, and the external appearance of the carcass remained relatively stable until 1.8 logADD, marking the emergence of maggots. However, decomposition dramatically accelerated after reaching 1.8 logADD, coinciding with maggots hatching from eggs and their commencement of scavenging. In contrast to larger ones, the hastened decomposition of small carcasses can be attributed to the relatively substantial volume of Diptera larvae within the small carcasses, expediting colonization and utilization. Therefore, carcass mass should factor into postmortem interval estimation based on the degree of body decomposition.