2023-05-08 19:49:56
Flies are often annoying: they fly over food, rest on the body and buzz. However, they constitute a fundamental part when unraveling the mysteries surrounding a crime because they are the first insects to arrive and colonize a decomposing body. It is not only about human beings, but it covers all kinds of vertebrates, such as reptiles, birds, fish, amphibians and mammals. Studying the fauna that arrives at the corpses allows us to obtain information on how and when that living being died, and forensic entomology is in charge of this.
The Scientific news agency of the National University of Quilmes visited the Laboratory of Applied and Forensic Entomology from this house of studies to discuss the work they do. “We investigate which are the species of flies that colonize decomposing bodies because allow us to find out when was the approximate date on which that organism died”, he tells the Agency Monica Chirinodirector of the Laboratory and professor at UNQ.
When a corpse is exposed to the action of insects, they begin to colonize it: Flies lay eggs, which then develop into larvae and feed on the body. Later, other types of fauna arrive, such as beetles and flies of different species.
Chirino explains that “Studying flies allows us to travel back in time”, and exemplifies: “If we find a body, which is unusual, it will have certain characteristics. It can be recently or long ago, naked or clothed, stabbed or buried. What we have to find out is how long that body has been there. So, since the flies are the first to detect it and lay their eggs that will later be larvae, we must identify the species in question and compare it with the data we have in the laboratory”.
Depending on the place and time of year in which the vertebrate dies, the types of flies that lay eggs first will be. Thus, for example, in the urban area of the southern zone of Buenos Aires the most abundant flies are called “Lucilia sericata” (metallic green fly) and “Lucilia cuprina” (bronze colored fly) and to a lesser extent “Lucilia ochricornis”. .
Under this framework, the Conicet researcher also continues the example. “There are flies that are rural and others that are urban. So, if the body appears in the field but has city fly eggs, that means it was moved and it is not there where death occurred, as well as if it has eggs or larvae from hot weather and it is already cold, it means that it died a while ago”.
Do they survive in water?
Within the Laboratory of Applied and Forensic Entomology, Lucila Salanitrograduate in Biotechnology from UNQ and doctoral fellow from Conicet, investigates the development of the larvae of the fly Lucilia sericata in a submersion context. Interviewed by this halfthe researcher reports: “We found that The eggs of this fly (which are airborne) survive in water for up to six hours and their development until they become larvae is not affected.”.
“It’s a partial submersion, that is, one time inside the water and another time outside. It is as if a body had been thrown into the river and the tide had brought it to the surface. What these results allow is consider the possibilities. For example, if the eggs did not survive, it is because the body was submerged for more than six hours.or if the eggs of this species of fly that is not aquatic are present, it is because the body died on land and then moved to the water,” Salanitro details.
To reach this result, the researcher placed mother fly eggs on pieces of meat, submerging them at different heights (25 cm, 15 cm and 5 cm) and for different time intervals. She then removed them and allowed the vital development of the larvae to continue at room temperature.
mushrooms help too
If the investigation carried out by Salanitro begins at the time of the death of the body, that of Anabella Massaccesi He is at the other end of the road, when several years have passed since his death. She is doing her undergraduate thesis in Biotechnology in this laboratory and characterizes different fungi that appear in bone remains after a long time of being buried. For it, works in the exhumations that are carried out in the Ezpeleta Cemetery.
“The idea is to be able to determine how much burial time the person has. We are talking about years so sometimes there are skeletal remains, like a jawbone, and sometimes there is nothing left.”, explains Massaccesi a la Agency. And he continues: “From time to time, the cemetery transfers the remains of graves to a common grave. So, with the required permissions, I grab the bones, I scrape them with sterile swabs and I take these samples to the laboratory”.
Through different materials, the thesis student evaluates the development of each fungus and performs a characterization. “The problem is that the vast majority of fungi are not known, Forensic mycology is not developed worldwide, and in Argentina there are only three people who specialize in this. So my job is to characterize the fungi and compare them. I work with fungi from bone remains of more than forty years, twelve years and three months to find out if they change or if they are the same”.
From the micro to the macro, forensic entomology works with very small elements that are of vital importance in the extensive joint work carried out by detectives, police officers and judges.
#Flies #fungi #key #partners #solve #crimes #dubious #deaths #work #Argentine #scientists #forensic #entomology