Utilization of Blow Flies (Phormia regina) as Vertebrate Resource Diversity Indicators

Abstract

Blow flies are often utilized in the field of forensic science due to their ability to aid in the estimation of time since death. Currently, estimations of postmortem interval require assumptions to be made and are prone to a margin of error, prompting research that may contribute to more accurate postmortem interval estimations and help to fill in the gaps of unknown information. Blow flies are necrophagous, feeding on feces and carrion, and therefore, are constantly sampling the environment. This behavior can be exploited in order to monitor the biodiversity in an environment. Through analysis of DNA isolated from the guts of blow flies, information can be obtained regarding what animals have died in an environment, what animals are still living in that environment, and the abundance and diversity of the animals present in a specific environment. Using fly-derived ingested DNA is a viable method for vertebrate resource identification and biodiversity monitoring. Over the course of a two-summer sampling period, in and around two national parks, a total of 162 blow fly (Phormia regina) samples returned a positive vertebrate DNA identification, with 33 species identified from five animal orders. Of the total number of flies collected and analyzed, 23.58% returned a positive vertebrate species identification. The method detected both abundant and common species based on National Park surveys, as well as some uncommon or unknown to the park species. In the SE region, 9 individuals belonging to the Rodentia order, 12 individuals belonging to the Artiodactyla order, 21 individuals belonging to the Carnivora order, 1 individual belonging to the Cingulata order, and 3 individuals belonging to the Lagomorph order were detected. In the SE region, 63% of the individuals detected belonged to the common category, 14% of the individuals detected belonged to the uncommon category, and 23% of the individuals detected belonged to the not in park/unknown category. In the NW region, 42 individuals belonging to the Rodentia order, 46 individuals belonging to the Artiodactyla order, and 28 individuals belonging to the Carnivora order were detected. In the NW region, 52% of the individuals detected belonged to the abundant category, 36% of the individuals detected belonged to the common category, and 12% of the individuals detected belonged to the uncommon category. The relative biodiversity of the sampled environment can be inferred. In the SE region, the Shannon Biodiversity Index was calculated to be 2.28 with an evenness of 0.844, while in the NW region, the Shannon Biodiversity Index was calculated to be 2.79 with an evenness of 0.855. Unsurprisingly, there was greater biodiversity in the Northwest Park samples than in the Southeast Park samples. Additionally, the ideal weather conditions for blow fly collection were determined be at a temperature of between 60- and 80-degrees Fahrenheit, a relative humidity between 50% and 60%, no precipitation, and a wind speed between 2 and 8 miles per hour. This information has further implications in the field of forensic science, specifically dealing with wildlife forensics, pathogen distributions, and can help to improve accuracy in regards to postmortem interval (PMI) estimations.