Chemotaxonomic Profile and Intraspecific Variation in the Blow Fly of Forensic InterestChrysomya megacephala(Diptera: Calliphoridae)

Abstract

Necrophagous insects such as blow flies (Diptera: Calliphoridae) are considered crucial in forensic entomology. Identification at species level and determination of larval stage are the basis for estimation of postmortem interval (PMI). Insect evidence can also be used in the determination of crime scenes, since body displacement is common. The aim of this study was to determine the chemotaxonomic profile and intraspecific variability of the forensically important blow fly Chrysomya megacephala (F. 1794). Adults were collected in the municipalities of Dourados-MS (Brazil) and Rio Claro-SP (Brazil), and then transferred to the laboratory for oviposition and development of the immature stages. Chemical analysis of cuticular compounds was performed by gas chromatography. Cuticular chemical profiles varied significantly between the two populations, as well as between developmental stages, supporting the use of these compounds as a complementary tool to help identify the species and its stages, along with geographical variability. This could greatly accelerate forensic investigations, eliminating the need to allow the fly larvae to develop until adult stage in order to confirm the species identity and sample origin.

Hydrocarbon and Fatty Acid Composition from Blowfly Eggs Represents a Potential Complementary Taxonomic Tool of Forensic Importance,

“…Indeed, Paula et al. found significant differences between HCs composition among different populations of C. megacephala , which suggest that the results found in this study represent a variation observed in only a population.…”

“…This feature extends the range of resources to streamline forensic investigations . However, it should be noted that HCs might vary according to genetic, but also environmental factors . Indeed, Paula et al.…”

“…Rearing and feeding of insects were performed following the methodology described by Paula et al. , to establish a colony. The eggs were separated into lots of 0.05 g eggs (312.6 ± 3.64 eggs).…”

“…Paula et al. demonstrated that different populations and stages of development of Chrysomya megacephala present specific cuticular hydrocarbons (HCs) profiles at each developmental stage, including the egg, each having a specific chemical profile indicating stage and population of origin. Gołębiowski et al.…”

“…Several authors also suggest that these compounds can be used as a complementary taxonomic tool to distinguish species of adult flies. Pechal et al.…”