Molecular identification of forensically important blowfly species (Diptera: Calliphoridae) from Germany

Forensic entomology applies knowledge about the behaviour and ecology of insects associated to corpses to homicide investigations. It is possible to calculate a minimum post-mortem interval by determining the age of the oldest blowfly larvae feeding on a corpse. The growth rate of the larvae is highly dependent on temperature and also varies between the different blowfly species infesting a corpse. It is, thus, crucial to correctly identify the species collected from a crime scene. To increase the quality of species identification, molecular methods were applied to 53 individuals of six different species sampled in Bonn, Germany: Calliphora vicina, Calliphora vomitoria, Lucilia caesar, Lucilia sericata, Lucilia illustris, and Protophormia terraenovae. We extracted DNA and checked a 229 bp sequence within the mitochondrial cytochrome oxidase subunit I. The sequences of the local flies were aligned to published data of specimens from other countries. We also studied the practical value of the analysed DNA region for their differentiation. All species were matched correctly by a Basic Local Alignment Search Tool (BLAST) search apart from L. caesar and L. illustris. Although molecular methods are very useful-especially if it is necessary to identify small fragments of insect material or very young larvae-we propose to use it only in addition to the conventional methods.