Recovery & identification of human Y-STR DNA from immatures of chrysomya albiceps (Diptera: Calliphoridae). Simulation of sexual crime investigation involving victim corpse in state of decay.

The number of sexual crimes in Brazil, as in several other countries, is very high. In many of these crimes the women raped are murdered and their bodies are found days later, in an advanced state of decomposition, with intense cadaverous fauna. Forensic Entomology studies insects and other arthropods that can be used in the expert analysis of various types of crimes. Diptera, the order of insects that comprises the two-winged or true flies, represents one of the largest known groups of insects and is the principal source of cadaveric entomofauna. Members of its Calliphoridae family are observed in cadavers in all phases of decomposition. The retrieval and identification of human Y-STR DNA from the gastrointestinal tract of Calliphoridae species Chrysomya albiceps maggots and pupae can provide a good tool for the gathering of evidence in sexual crime investigations involving rape and death, in which the abandoned victim's body is found in a putrefied state. In this study, the animal model used was a female pig, Sus scrofa, which was sacrificed in a forested area with three shots from a 0.40 calibre Taurus pistol, and inoculated with semen to its anal and vaginal regions, simulating rape and homicide. During decomposition, 20-80 maggots were collected every 24 h and preserved in 70 % alcohol, totalling 289 maggots and 157 pupae (446 immatures) over a period of 14 days (336 h) of decomposition. Each maggot was then dissected for removal of the digestive tract, which was placed in extraction buffer. The molecular phase proceeded with extraction, quantification, amplification and capillary electrophoresis of samples, testing 16 STR loci of the Y chromosome. It was possible to establish a partial Y-STR DNA profile, with the amplification of up to eight sites, by considering a combination of the samples taken at hours 144 h, 168 h, 192 h, 216 h, 240 h, 288 h, 312 h and 336 h.

DNA-based identification of forensically important species of Sarcophagidae (Insecta: Diptera) from Rio de Janeiro, Brazil.

Sarcophagidae, or flesh flies, are of great importance in forensic entomology, but their effective application requires precise taxonomic identification, which relies almost exclusively on characteristics of the male genitalia. Given that female flies and larvae are most abundant in animal carcasses or on corpses, precise morphological identification can be difficult; therefore, DNA sequencing can be an additional tool for use in taxonomic identification. This paper analyzes part of the mitochondrial cytochrome c oxidase subunit I (COI) gene from three Sarcophagidae species of forensic importance in the City of Rio de Janeiro: Oxysarcodexia fluminensis, Peckia chrysostoma, and Peckia intermutans. COI fragments of 400 bp from 36 specimens of these three species were sequenced. No intraspecific differences were found among specimens of O. fluminensis, but P. chrysostoma and P. intermutans each had two haplotypes, ranging from 0 to 0.7%. The interspecific divergence was 8.5-11.6%, corroborating previously reported findings.

Differential Diptera succession patterns onto partially burned and unburned pig carrion in southeastern Brazil / Diferenças no padrão de sucessão de Diptera em carcaças de porco parcialmente carbonizadas e não carbonizadas

In the present contribution we compared the entomological succession pattern of a burned carcass with that of an unburned one. For that, we used domestic pig carcasses and focused on Calliphoridae, Muscidae and Sarcophagidae flies, because they are the ones most commonly used in Postmortem Interval estimates. Adult and immature flies were collected daily. A total of 27 species and 2,498 specimens were collected, 1,295 specimens of 26 species from the partially burned carcass and 1,203 specimens of 22 species from the control carcass (unburned). The species composition in the two samples differed, and the results of the similarity measures were 0.875 by Sorensen and 0.756 by Bray-Curtis index. The results obtained for both carcasses also differ with respect to the decomposition process, indicating that the post mortem interval would be underestimated if the entomological succession pattern observed for a carcass under normal conditions was applied to a carbonized carcass.

Nesta contribuição, nós comparamos o padrão de sucessão entomológica de uma carcaça carbonizada com outra não carbonizada. Para tal, nós usamos carcaças de porcos domésticos e focamos nos dípteros Calliphoridae, Muscidae e Sarcophagidae, por estes serem os grupos de insetos mais comumente usados na estimativa do intervalo pós-morte. Moscas adultas e seus imaturos foram coletados diariamente. Um total de 27 espécies e 2.498 espécimes foi coletado, 1.295 espécimes de 26 espécies na carcaça parcialmente carbonizada e 1.203 espécimes de 22 espécies na carcaça controle (não carbonizada). A composição específica das duas amostras foi diferente e os cálculos de similaridade resultantes foram 0,875 pelo índice de Sorensen e 0,756 pelo índice de Bray-Curtis. Os resultados obtidos para ambas as carcaças também diferiram em relação ao processo de decomposição, indicando que o intervalo pós-morte poderia ser subestimado se o padrão de sucessão entomológica observado na decomposição de uma carcaça sob condições normais fosse aplicado a uma carcaça carbonizada.

Differential Diptera succession patterns onto partially burned and unburned pig carrion in southeastern Brazil.

In the present contribution we compared the entomological succession pattern of a burned carcass with that of an unburned one. For that, we used domestic pig carcasses and focused on Calliphoridae, Muscidae and Sarcophagidae flies, because they are the ones most commonly used in Postmortem Interval estimates. Adult and immature flies were collected daily. A total of 27 species and 2,498 specimens were collected, 1,295 specimens of 26 species from the partially burned carcass and 1,203 specimens of 22 species from the control carcass (unburned). The species composition in the two samples differed, and the results of the similarity measures were 0.875 by Sorensen and 0.756 by Bray-Curtis index. The results obtained for both carcasses also differ with respect to the decomposition process, indicating that the post mortem interval would be underestimated if the entomological succession pattern observed for a carcass under normal conditions was applied to a carbonized carcass.