Effects of elevation, season and bait type on assemblage of forensically relevant blow flies (Diptera: Calliphoridae) in contrasting habitats of northwestern Arizona

Abstract

Blow flies represent one of the most forensically significant insects in legal investigations. Their habitat-specific abundance and temperature-dependent development rates can help estimate a post-mortem interval (PMI), cause of death and post-mortem movement of a deceased body. As the role of forensic entomology expands in human and wildlife criminal investigations, there is a need for updated regional surveys for blow fly species. All recent and previous blow fly surveys in Arizona have been limited to the southern and central ecoregions. The objective of this study was to identify blow fly species between two contrasting habitats in northwestern Arizona—the Black Mountains (Mojave Desert) and the Hualapai Mountains (Arizona/New Mexico Mountains). This research aimed to assess the impacts of food source (game meat (javelina; Tayassu tajacu) compared to chicken (Gallus domesticus) liver), seasonality and elevation on blow fly biodiversity. Each habitat had three site locations at different elevational gradients (low, middle, high) with four bait traps deployed at each site (two of each bait type). This study found a significant difference in the biodiversity of blow flies between and within each habitat seasonally, as well as elevational variation within each habitat. Bait-preference also was statistically significant for overall abundance, and two indicator species for each bait type were identified. Additionally, this research presents the northernmost recorded presence of Chrysomya rufifacies in Arizona, as well as the first records of Cynomya cadaverina and Calliphora alaskensis in the state. The data collected establishes an important baseline for these understudied regions of Arizona and facilitates a wider use of blow flies in forensic investigations for rural areas of Mohave County, AZ.