The change in human DNA content over time in the artefacts of the blowfly Lucilia cuprina (Meigen) (Diptera: Calliphoridae)

Adult blowflies can act as vectors of human DNA by depositing faecal or regurgitation spots (termed artefacts) after feeding on meals of human biological fluid. Given the number of backlog cases in many forensic laboratories, it is important to know the maximum time period any human DNA within a fly artefact can remain unextracted before the DNA degrades to unusable levels. The present study aimed to determine whether or not the human DNA content in fly artefacts deposited by the blowfly Lucilia cuprina changed over time, and also to provide a timeframe for forensic biologists in which the extraction of human DNA from fly artefacts should be attempted. Both the blood and semen data showed that the amount of human DNA that could be extracted increased over the first 400 days, but had decreased to one-month levels by 750 days. The saliva data showed no changes over the 60-day time period in the amount of human DNA that could be extracted. © 2011 .