Colonización de cuerpos semisumergidos por especies de dípteros de interés forense en el Alto Valle de Río Negro

Abstract

Forensic entomology is the science that studies the insect fauna associated with a corpse, with the primary objective of estimating the post-mortem interval, that is, the time from death to the discovery of the body. This information is crucial for reconstructing events, determining circumstances of death, linking or ruling out suspects, and reinforcing witness testimonies. Additionally, insects can provide data on the time of year the event occurred and the possible relocation of the body, as the presence and distribution of species vary according to the season and environment. The first insects attracted to a corpse are flies of the order Diptera. Females lay their eggs on the decomposing body and, depending on climatic conditions, larvae emerge and consume the tissues of the corpse. These larvae molt twice and, at the end of the larval stage, seek a place to transition to the pupal stage through a process called post feeding dispersal. The pupae bury themselves and remain immobile until they complete metamorphosis and emerge as adults. The final location of the pupae depends on where the larvae abandoned the corpse and the context in which the body is found. Larval development will depend on the climatic conditions, temperature, and humidity of the environment where the body is located. In many cases, corpses are moved and abandoned in bodies of water to hide them or eliminate evidence. In the Alto Valle de Río Negro region, we are surrounded by many bodies of water, and this activity can be quite common. Water is a variable that can alter the conditions of a corpse and modify the behavior of the insects that settle on and feed on it. Therefore, the objective of this work was to understand the behaviour of forensically relevant dipteran species on semisubmerged bodies in order to refine sample collection and improve forensic analysis. To meet the objectives, two halves of a pig were used as treatment and control, and comparative tests were performed. One part was placed in a semisubmersion condition in a canal 50 cm deep, and the other, as a control, on the ground. Both halves were observed at two-hour intervals, interrupting the process between 10 pm and 8 am, for a period of 48 hours. This two-hour frequency was maintained until the eggs hatched and the first larvae emerged. To quantify and compare the number of eggs, the oviposition area was used as the response variable.