Description of the life stages of forensically important Coleoptera in the central Free State

[摘要] The identification and the development of beetles of forensic importance remainunderstudied when compared to the number of studies conducted on developmentand identification of the life stages of flies of forensic importance in central Free State.This hinders our understanding of what beetle species are associated withdecomposing carcasses and how we can use their immature stages and theirdevelopment to determine Post Mortem Interval. It is important to make correctspecies identification when calculating PMI because development data of one speciescannot be used for the forensic significance of another species, even in closely relatedspecies. In recent successional studies that have been conducted in central FreeState, beetles of forensic importance have been identified to family or genus level.Carcasses used in this experiment were domestic pig (Sus scrofa domesticus) with atotal of three pigs between the weights range of 32.5-49kg, Cape baboon (Papioursinus) with a total of two baboons weighing 18 and 19kg and one sheep (Ovis aries)weighing 44kg. The carcasses were placed on the Western side of the campus of theUniversity of the Free State. The carcasses were allowed to decompose and insectswere collected twice a day during the decomposition period. The aim of this project was to describe morphological characteristics, used to developkeys with which to differentiate between beetle species (adults and immatures)associated with decaying carcasses in central Free State.A total of eighteen beetle species representing eight families of forensic importance(Silphidae, Staphylinidae, Histeridae, Dermestidae, Cleridae, Trogidae,Scarabaeidae, and Nitidulidae) were collected from the carcasses. Some beetlespecies were reared under laboratory conditions with the intention of obtainingimmatures life stages that were not found in the field. The rearing temperature was setto 28 ± 2ºC and a photoperiod of 12L:12D was maintained in the insectarium. A 3 to4cm soil layer was laid down in some breeding containers and moist cotton wool was used to maintain the soil moisture levels. In some breeding containers, only sawdustand styrofoam were used as pupation refugia.Of eighteen species collected, only two species completed their development underlaboratory conditions. Some of the beetles that were collected are already describedin literature, and these beetles were redescribed using both external and internal(internal male genitalia) morphological characteristics. Some of the species were onlyidentified to genus level and, in future, the morphological characteristics andmicrographs provided in this study will help with identification for both successionaland developmental studies.

[发布机构] University of the Free State