Pupal age estimation of forensically important Megaselia scalaris (Loew) (Diptera: Phoridae)

In addition to causing myiasis in humans and animals, Megaselia scalaris (Loew) has been reported as a forensically important fly. The determination of a minimum postmortem interval (PMI) often relies on the determination of the age of the larvae and pupae. The pupal stage represents about 50% of the immature development time and the pupal age may therefore serve as an important tool in entomological minimum PMI estimation. The present study focuses on the key developmental processes during metamorphosis of M. scalaris pupae at different constant temperatures (18, 21, 24, 27, 30, 33 and 36 °C). The average minimum duration of development from prepupa to adult emergence was inversely related to temperature, ranging from 170.65 ± 1.39 h at 33 °C to 608.80 ± 13.26 h at 18 °C. The pupa did not develop at 36 °C. Some morphological features that changed during development within the puparium could be used as age markers. According to these changes, the pupal stage of M. scalaris was divided into 10 stages which could be used for both sexes.