Seasonal variation and the abiotic influences on blow fly (Diptera: Calliphoridae) community composition in a forested preserve in central Oklahoma, USA

Blow flies (Diptera: Calliphoridae) are commonly used as evidence in legal investigations as they are typically the first arthropods to colonize decomposing remains. Distribution data and development tables for blow flies are used by forensic investigators to estimate a time of colonization (TOC), which is used to infer a minimum post-mortem interval (minPMI). Blow fly activity and community composition is driven by biotic and abiotic factors, therefore local populations differ across geographic regions. The goal of this study was to determine the seasonal blow fly community composition of central Oklahoma, USA and the abiotic factors, ambient temperature, relative humidity, barometric pressure, and average rainfall, that influence it. Each week from September 6, 2021 to September 9, 2023, blow flies were collected from 24-hour beef-liver baited traps placed in Oliver’s Woods Ecological Laboratory and Natural Area (Norman, OK, USA). A total of 12,605 blow flies were identified from 14 different species with Lucilia coeruleiviridis (Macquart), Cynomya cadaverina (Robineau-Desvoidy), and Phormia regina (Meigen) comprising the greatest total. An analysis of similarity showed the blow fly community composition significantly differed across the seasons. A PCA analysis on the abiotic factors and species determined that average relative humidity and average ambient temperature explained the majority of the variance in community composition. Data from this consecutive two-year study adds to the breadth of knowledge regarding abiotic factors and their effects on seasonal blow fly community composition. These data may be helpful in criminal and civil cases within the southwestern US where insect evidence is often overlooked.