STR typing of human DNA from fly larvae fed on decomposing bodies

In homicides with entomological evidence, it may be important to prove the presumed association of fly larvae to a corpse, especially if it is in doubt whether all maggots used for entomological expertise developed and fed on it. The present study demonstrates for the first time the possibility of analyzing human microsatellite DNA present in the digestive tract of necrophagous larvae that fed on decomposed bodies with a postmortem interval up to four months. The obtained human STR profiles support the association of a maggot to a specific corpse. In addition, the identification of the host species (e.g., animal source like pig) can be achieved by analysis of the cytochrome b gene. Maggots were collected from 13 corpses after various postmortem intervals and STR typing and HVR amplifications were performed using their crop contents. In seven cases, a complete STR profile was established, in two cases, an incomplete set of alleles was obtained, and in four cases, STR typing was not successful. HVR analysis was successful in all cases except one. The time of storage of the maggots and the length of the postmortem interval up to 16 weeks appeared to have no particular influence on the quality of the results.