Phenotypic variation in developmental characteristics of the black blow fly Phormia regina (Diptera: Calliphoridae) across New Jersey

Blow flies (Diptera: Calliphoridae) collected from human remains can greatly assist homicide investigators in determining a time since death by producing a minimum post mortem interval (min-PMI). However, some species of blow fly vary in their developmental characteristics based on geographical region, potentially reducing the accuracy of the min-PMI. Black blow flies (Phormia regina) are common throughout much of the United States, but little is known of their biology in the northeast. To address this deficiency, we examined this species’ phenotypic variation from three different geographical regions across New Jersey (north, central, and south). This is the first study investigating the developmental variation of this species in addition to examining intrastate populations of P. regina. Populations of P. regina from each region were studied at 25 °C, 14:10 h L: D and ~ 56% RH. In total, 3,900 first instar larvae were used in this experiment (13 containers of 100 larvae per region). Developmental characteristics such as survivorship, pupal weight, and adult weight were quantified. Of the original 3,900 larvae, 1,978(51%) pupated and 1,617(41%) became viable adults. The southern population had the lowest mean weight for both pupae (0.0267 g) and adults (0.00651 g), while the northern population had the largest mean pupal weight (0.0317 g) and the central population had the largest mean adult weight (0.00784 g). Our results will improve min-PMI estimates across New Jersey, and future work will involve increasing the temporal replication of the experiment.