Insects involved in decomposing corpses in the Constantine region-Algeria

Forensic entomology comprises three main disciplines, which are: urban entomology, the entomology of stored foodstuffs and criminal entomology which we are interested in. When an animal species dies, it will be quickly visited and colonized by many invertebrates. The majority of which will be insects and it is fi rst necessary to make a clear distinction between the different functional groups which can be found on a corpse [1]. So, forensic entomology is concerned with the application of the study of insects and other arthropods, which have an important role in the service of justice [2].


Introduction
Forensic entomology comprises three main disciplines, which are: urban entomology, the entomology of stored foodstuffs and criminal entomology which we are interested in. When an animal species dies, it will be quickly visited and colonized by many invertebrates. The majority of which will be insects and it is fi rst necessary to make a clear distinction between the different functional groups which can be found on a corpse [1]. So, forensic entomology is concerned with the application of the study of insects and other arthropods, which have an important role in the service of justice [2].
Constantine region located in eastern Algeria and characterized by a semiarid climate with cold winter. Our study aims to identify the types of insects that contribute to the analysis of corpses (the body of an animal) according to climatic conditions of the study area.

Material and methods
The presence and activity of insects also infl uence the process of decomposition as different types of organisms are attracted at each stage of decomposition. In our current study, we followed the decomposition of dog corpse (15-kilogram).
It was obeserved near the Biosystematic and ecology of Arthropods laboratory at the Mentouri Constantine University (36°20'16.20"N; 6°37'33.32"E, 571 m altitude), on the day of 15february. After, the corpse was put in a cage to protect it from predators. The study period lasted approximately three months, from 15 February to 26 April, 2018.
Samples were taken at an hourly rate daily to the laboratory, every two hours from 8 a.m. until 5 p.m. It were taken from the various traps installed in the cage (barber and yellow traps) and also direct captures from the corpse. In the laboratory, insects were sorted and classifi ed using classifi cation keys [3,4], magnifying lenses and various tools used in the study of insects Table 1. Forensic medical entomology is concerned with studying insects related to a human body and one of its most important applications is to determine the time that has passed since death. As for forensic entomology, it is concerned with the study of throwing fl ies, the fi rst carcasses of the carcass , which varies according to the surrounding milieu and season of the year [6] and the ability to incubate and breed in the laboratory [7].

Discussion and conclusion
In our current study, 21 species were identifi ed, with the fi rst arriving species being from the Diptera order, followed by the Coleoptera rank, and in the latter the species belonging to the Hymenoptera rank. The results of this study are consistent with the fi ndings of many researchers [8][9][10].
According to the study of Bouleknefet in the Skikda region in 2015 and 2016 [11,12], two species that were not registered in our current study were identifi ed, namely Phormia regina and Lucilia illustis due to the conditions of each region. Skikda is a region with a humid climate, and the Constantine region under study is semi -dry climate.
The study confi rms the importance of using forensic forensics in investigations and recommends that such studies be circulated to all regions of the country, and to establish a database of the species present in each region to facilitate judicial investigations using forensic entomology. And it will stress the importance of detailed analysis of the phenomenon of decomposition and climatic conditions, whether short or long-term when estimating the time of death.
This work gave us an idea of the diversity of the scavenging entomofauna in the Constantine region. Our study remains incomplete and needs to be deepened research remains necessary to identify and study the biological cycles of the main species and the effects of climatic factors on the distribution of these insects.