Gene expression as age estimation marker in the larval stages of the forensic blowfly, Chrysomya albiceps, at different temperatures

Abstract

The blowfly Chrysomya albiceps (Diptera: Calliphoridae) has been known to breed in both animal and human carcasses in different geographical regions and is considered an important post-mortem indicator in forensic entomology. Determining the age of its larvae is an essential tool for the accurate determination of post-mortem intervals (PMI). This study adopted a molecular-based approach for age determination of the immature stages of the blowfly, C. albiceps, by evaluating the genes 15_2, 2014192, EcdR, AR, hsp90, and Actin, during larval development at different temperatures. Targeted genes were amplified by real-time PCR (RT-PCR), and the resulting amplicons were normalized against the two housekeeping genes, rp49 and 19_2. Data showed that the expression profile of AR was constant throughout all larval developmental stages at all tested temperatures. 2014192 showed low expression levels throughout the 1st, 2nd, and 3rd larval stages. Hsp90 and EcdR showed different expression profiles. The expression of 15_2 was low at the tested temperatures and was undetectable on most days. Collectively, the results of this study indicate that larvae exhibit temperature-dependent and age-specific up- and down-regulation in the expression profile of the targeted genes. This may indicate a possibility to be utilized as age estimation markers for C. albiceps.

Keywords: Blowfly; Forensic; Gene expression; Larval age; Temperature.