Cuticular chemical composition as a tool for the identification of puparial cases of some forensically important Egyptian blow flies

Abstract

Abstract Cuticular chemical compounds for many insect species were proven to be unique and species specific. Because of their uniqueness, analysis of such chemical profiles, especially cuticular hydrocarbons was used for many purposes including identification of insects. Blow flies are one of the first flies that reach corpses so play a significant role in estimating the minimum post mortem interval. Accurate estimation depends on precise identification of the collected specimens. When only damaged empty puparial cases were left behind, morphological and even molecular identification methods of blow flies is so problematic. The aim of this study was to analyze the chemical compositions of the puparial exuviae of Lucilia sericata, Chrysomya albiceps and Chrysomya marginalisusing gas chromatography/mass spectrometry (GC–MS) to evaluate their accuracy in Dipteran identification. Adults were collected from Giza and Cairo Governorates and reared under laboratory conditions until emergence of first-generation adults to obtain their empty puparial cases. GC–MS was used to analyze the chemical composition of these exuviae. Twelve classes of chemical compounds were identified from the three species at retention times 18.78 to 35.03. Alcohol represented the highest percentage (28.6%) of compounds in Lucilia sericata profile. Meanwhile, alkanes (n-alkanes, branched alkanes and cycloalkanes) constitute the major cuticular components of the three fly species with the highest percentage in Chrysomya marginalis cuticle. These findings could be considered as a preliminary step toward using hydrocarbon composition as a feasible tool for differentiation between forensic species in Egypt.