Analysis of alternative food sources for rearing entomological evidence

Forensic entomology is a well-established tool for evaluating the death, or abuse, of a person. Insect evidence provides valuable information as related to time of colonization and movement of remains from one location to another. Blow flies (Diptera: Calliphoridae) are commonly found on human remains throughout most stages of decomposition, and when entomological evidence is collected these taxa tend to be the most numerous. However, very few crime laboratories across the country have collection and rearing protocols for these forensically important insects. A lack of knowledge in collection techniques and limited access to an appropriate food source are the main reasons for absence in adequate collection and rearing protocols. Thus, when crime scene investigators or pathologists collect insects, they are often mishandled (e.g., placed into containers with no air holes, no food, or a food source that is not sustainable for their development). To address this issue, we analyzed easily accessible and cost-efficient alternative food sources for blow flies; specifically, tuna and wet cat food compared to beef liver (control). Survivorship and development were examined for each food source using the blow flies Phormia regina (Meigen) (Diptera: Calliphoridae) and Cochliomyia macellaria (Fabricus) (Diptera: Calliphoridae). These findings provide an overview of possible alternatives that could be used as a sustainable food source in crime laboratories when immediate action from a forensic entomologist cannot be obtained.