Prediction of the Number of Firearm Shots by Using Lucilia sericata (Diptera: Calliphoridae) Larvae with an Inductively Coupled Plasma -Mass Spectrometry (ICP-MS) Technique

In forensic entomology, researchers utilize insects to determine the time of death, cause and location. This firearm-related study focused on two main objectives. The primary aim was to evaluate the relationship between the number of shots and gunshot residue (GSR) concentrations detected in larvae feeding on firearm-shot meat samples using Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae). We also aimed to investigate the effect of GSR on the weights and lengths of larvae during feeding with GSR-containing meat samples. A short-barreled gun and 9x19 mm Parabellum-type bullets were used to produce gunshot residue on meat samples. Twenty-four pieces of meat were classified into four groups including control samples (n=3) (GSR0; larval feeding without shot), GSR1 (n=7) (larval feeding with one shot), GSR2 (n=7) (larval feeding with two shots), and GSR3 (n=7) (larval feeding with three shots). Lucilia sericata eggs were put into the bullet holes and incubated at 28°C temperature for 72 hours. After the incubation period, the third-instar larvae samples were collected, and 10 larvae samples were analyzed by Inductively Coupled Plasma-Mass Spectrometry to detect Sb, Ba, and Pb concentrations. Data were analyzed using two-way analysis of variance (two-way ANOVA) in R software. Comparative results showed 0.817, 0.854 and 0.886 correlation coefficients for Sb, Ba and Pb, respectively, and significant increases in Ba and Pb concentrations were detected in larvae, depending on the number of shots, while developmental changes on lengths and weights were insignificant except GSR3. Simultaneous detection of Sb, Ba and Pb in larvae found in a crime scene contributes to the interpretation of firearm cases by considering other uncertainties.