D3008: Calliphoridae larval mass development during carrion decomposition

Scientific investigations of the necrobiome and its constituents have demonstrated that dipteran insects of forensic interest are primary organisms associated with carrion colonization and decomposition. The host postmortem microbial community undergoes changes that precede insect colonization and continue to change with exogenous fly larvae that assimilate and change the host microbiome over time. What is less understood is the influence of seasonal changes on larval mass development and carcass microbial ecology, which are known to be sensitive to weather variables (e.g., humidity, temperature, precipitation) that seasonally change. To investigate how seasonal weather variables affect forensic insect and microbial growth during carcass decomposition, we used neonatal swine carcasses (N=6) as models for mammalian decomposition in three decomposition studies during July 2022 (Summer) and October 2022 (Fall), and April 2023 (Spring). Three body sites were sampled along with dipteran larval masses and individual larvae to characterize microbial communities of both the carcass and insects. Sampling occurred twice a day for 7 days in the Summer and 32 days in the Fall; samples were collected in the morning (6:00 - 9:00) and afternoon (14:00 – 16:00). Preliminary analyses revealed Calliphoridae were the most predominant dipteran family, with Lucilia spp. having the highest relative abundance. Temperatures read by data loggers ranged from 8°C to 39°C in the Summer and –2.3°C to 35.4°C in the Fall. Understanding the ecological dynamics of the necrobiome among seasons may inform entomological evidence collection, analyses, and interpretation important for microbial trace evidence and postmortem interval estimates.