Of pigs and men-comparing the development of Calliphora vicina (Diptera: Calliphoridae) on human and porcine tissue

Over the last decades, studies on juvenile development of forensically important Diptera were performed by using non-human tissues (e.g., beef liver) as a nutrition medium. Such developmental data are used as a reference in determining the age of juvenile necrophagous insects sampled from a human body and thereby to estimate the minimum postmortem interval (PMI_min). Despite the acceptance of these studies in the forensic community, some might ask whether such data appropriately reflect the growth of blow flies on human tissue. We, therefore, studied larval growth rates and development times of Calliphora vicina (Diptera: Calliphoridae) on human muscle tissue as well as on pork loin, pork liver, and minced pork at 25 °C. Larval growth rates were significantly (p < 0.001) slower on pork loin and pork liver compared to human muscle tissue. Nonetheless, the time at which the examined developmental landmarks "post-feeding larvae," "pupae," and "adult fly" were reached was similar for all tissues, with significant delays in first fly eclosion only for specimens reared on pork loin (p = 0.027) and pork liver (p = 0.036). Our results highlight the fact that not all porcine tissues are similarly suitable for producing sound growth data for necrophagous Diptera. At present, we recommend the use of minced pork as a non-human nutrition medium, since our results show no developmental differences on this diet compared to human tissue.