Edaphic fauna and buried corpses: arthropods found in coffins during exhumations in Granada (Spain)
ABSTRACT BACKGROUND: Mateo Orfila and Pierre Mégnin were the first researchers that exploited exhumations to summarize the fauna associated with corpses. While Orfila simply enumerated the species he found, Mégnin laid the cornerstone for the forensic entomology when he grouped species in eight waves called "workers of the death". Since then, many studies were performed but very few dealt again with the problem of buried corpses and the information that exhumations can provide. In October 2008, a series of restoration works began at the San José graveyard (Granada, Spain). In order to move to an ossuary those
corpses which were not claimed within a period of one year, 20 nonjudiciary exhumations were performed. We focused our sampling on mites (Acari: Oribatida, Prostigmata and Mesostigmata) and Collembola. We wanted to test if there were differences among the faunistic composition of burials with different Post-burial Intervals (PBI).
METHOD: Sampling of mites and collembola was conducted in three stages. First of all, we took dust samples with a manual vacuum above and below the body, taking special care on the bottom and corners of the coffins. Second, we removed manually pieces of soil that penetrated through the chinks of wood. Finally, we inspected again the corpses and coffins once removed the corpse and running arthropods were captured with the help of a brush soaked in saline solution. Dust collected by manual vacuuming was processed by a flotation method in a sodium chloride saturated solution (Arlian method modified by Solarz). Soil found in the tombs were sampled with the help of Tullgren funnels using ethylene glycol as preservative liquid.
RESULTS: In a preliminary analysis, we grouped the fauna of each group (oribatid, mesostigmatid, prostigmatid mites and collembola) in 17 morphotypes, without identification purposes at first. Subsequently, we were able to observe an association between the occurrence of certain species and PBI, given the significative differences observed in the faunistic diversity of each group of exhumations. The biggest differences could be appreciated in the range of 5–10 years PBI, while certain stability was found in the first 1–5 years.
CONCLUSIONS: Given that we have observed significantive differences among groups, we can assert that the edaphic fauna can be used apart from the classic forensic markers (Diptera and Coleoptera) in the
assesment of the postmortem interval, when burial is close to the time of the death.