The Entomo-Toxicological Effect Of Dichlorvos on Cuticular Hydrocarbon Profiles of Some Sarco-Saprophagous Insects for Forensic Applications.

Abstract

Forensic entomology has relied on species-specificity, quantitative and qualitative variations of cuticular hydrocarbons to successfully carry out chemotaxonomic identification of insects based on species, age and gender. This work studied the effects of dichlorvos on the cuticular hydrocarbon profiles of some adult sarco-saprophagous insects of forensic importance that fed on dichlorvos-poisoned carrions for utility during death investigations. Cuticular hydrocarbons (CHCs) were extracted from adult insects of the species Chrysomya albiceps, Sarcophaga exuberans, Musca domestica, Hermetia illucens, Dermestes maculatus and Necrobia rufipes from both dichlorvos-poisoned and control pig (Sus scrofa Linnaeus) carrions and subjected to chemotaxonomic profiling using Gas Chromatography-Mass Spectrometry (GC-MS). A total of 41 CHCs were successfully identified from insects of both the dichlorvos-poisoned and control carrions ranging from C8 to C33 carbons consisting of majorly the n-alkanes, methyl branched alkanes and an alkene. There was a higher abundance of CHCs present in the insects of dichlorvos-poisoned carrions than the control group. The highest mean peak concentration and abundance of the CHCs was recorded by 2,6,10,14 -Tetramethyl Pentadecane (10.38 ± 0.53 μg/mg for dichlorvos-poisoned carrions and 8.99 ± 1.13 μg/mg for the control carrions). The visualization of the species-specific differences in CHCs compositions showed less overlapping CHCs clusters and quantitative metrics of principal component analysis plots of the insects from both carrion groups with high eigenvalues > 3 which were indications of good species level discrimination. The study showed that insects' CHCs profiles of dichlorvos-poisoned and control carrions exhibited uniqueness cum variations in terms of abundance and chemical identity.