Cuticular hydrocarbons as weathering biomarkers of empty puparia of the forensically important blowfly Calliphora vicina Robineau-Desvoidy, 1830 (Diptera: Calliphoridae) in soil v/s under room conditions

Abstract

Forensic entomology uses the age of insects, such as blow flies, to determine a minimum post-mortem interval (PMImin). Recent research has focused on using the analysis of specific cuticular hydrocarbons (CHCs) in adult insects and their empty puparia to estimate their age, as it has been shown that their profile changes are consistent with age. The current work is based on the weathering of five CHCs from empty puparia of Calliphora vicina that were stored in soil (field/outdoor) and non-soil (room/indoor conditions) based pupariation media for a total of six months. The experiment was conducted in a controlled environment chamber at a constant temperature of 25 ± 2 °C under constant darkness. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the cuticular hydrocarbons after they were extracted in n-Hexane. n-Pentacosane, n-Hexacosane, n-Heptacosane, n-Octacosane, and n-Nonacosane were the five CHCs investigated. Results showed that CHCs weathered more quickly in the soil than in the non-soil environment. It was also found that the abundance of Heptacosane increased in the samples during the fifth month when stored in a non-soil medium, while the abundances of all five CHCs were not detected after eight weeks onwards in soil pupation medium.