This article reports on a study in which artifacts produced by adults of Calliphora vicina, Cynomya cadaverina, Sarcophaga bullata, and Protophormia terraenovae were examined using a previously developed immunoassay to determine whether insect-derived stains could be distinguished from a range of human body fluid stains.
An immunoassay was previously developed as a technique to improve methods for detecting and analyzing fly artifacts found at crime scenes. The dot blot assay uses a polyclonal antiserum (anti-md3) based on a unique digestive cathepsin D found in cyclorrhaphous Diptera. In the current study, a lift technique was developed which permitted transfer of fly artifacts from test materials to filter paper for dot blot analyses. All species readily deposited artifacts on all test household materials regardless of diet consumed. Despite differences in texture and porosity of the household materials, artifacts of all species transferred to the filter paper. With all fly species, anti-md3 serum bound to artifacts produced after feeding on semen, blood, feces, urine, and saliva. By contrast, anti-md3 serum did not react with any of the human fluids tested, nor with any of the lifts from household materials not exposed to flies. There was no evidence of false positives with any of the fly species tested, regardless of diet consumed. There was also no indication of false negatives with any of the dot blot assays. These observations suggest that immunoassays using anti-md3 serum performed on a simple lift of suspected fly artifacts can be used effectively as a confirmatory assay to distinguish fly regurgitate and fecal stains from human body fluids. (publisher abstract modified)