Preliminary study of the succession pattern of necrobiont insects, colonising species and larvae on pig carcasses in Temuco (Chile) for forensic applications

Knowledge regarding the succession patterns of insects that visit carcasses as well as the other arthropod that colonise them and analysis of the parameters that are associated with larvae allow calculation of the minimum postmortem interval (PMI). This information is obtained from experiments carried out under specific geoclimatic conditions, which determine their application in forensic environments under similar conditions. The field study presented here is the first in Chile to analyse the decomposition process of pig carcasses and the associated succession of insects, colonising species and parameters related to larval masses. All of the larvae obtained from daily samples were measured (in mm), and their mean, range, standard deviation and stage of development (instars) were determined. The carcasses reached the dry remains stage in only 11 days. Seven species of Diptera visited the carcass during the process, but only two species colonised it by means of egg deposition followed by development of larvae: Cochliomyia macellaria (Fabricius) and Lucilia sericata (Meigen) (Diptera: Calliphoridae), which exhibited a duration of the development cycle from egg to adult of 21 days. The collected Coleoptera correspond to five predator species (Staphilinidae and Histeridae). From the results of this study, it can be concluded that only some of the insect species present in this region can provide information that can be used in forensic entomology and that analysis of larval masses of colonising species can be a valuable tool for determining the PMImin in this region of Chile.