ABSTRACT

One thing that is sure in life is the demise of an organism as it is certain that every living thing will one day die. The manner at which an individual dies and the latent fact surrounding his demise is very important in criminal investigation pertaining to bringing to light of ingredients of sort and details of fastidious deaths. This study was carried out to create data of arthropods’ succession on decomposing pig carrions as it’s very important for the successful implementation of the concepts of forensic entomology in the investigation of the facts of death.

A total of 24 pigs were used in this study in College of EducationWarri and Echiki Neke. Each pig was killed, taken to the study sites and guided with mesh which permitted the access of the insects and other arthropods but protected the carrions against other bigger animals. The experiment was repeated in both the wet and dry seasons at all the sampling stations. Manual method was used in the collection of insects on the decaying pig carrions with the aid of sweep nets for those insects that were flying by making 15 sweeps with the nets in each of the sampling occasion. Brushes were used to comb the animals’ bodies so as to collect hidden insects on the body of the carrions. Pam-Pitfall traps were used for collecting surface dwellers and second instars larvae collected from the carrions were bred to adult in the laboratory.On the carrions transferred from College of Education to Falcorp, 6 pigs were used during the wet and dry season, four pigs were deposited at the College while two were deposited at the Falcorp after 48 hours; two of the pigs at the College were transferred to the Falcorp to imitate the assailants’ deception. Each pig carcass was monitored for the period of 60 days. Data analyses were done by the Microsoft Excel and the Statistical Package for Social Sciences (SPSS) Analysis of Variance (ANOVA) deployed to establish variation in species abundance while non parametric indices of diversity were used to examine insect diversity and richness.

A total of 10,240 insects were collected representing 82 species and 39 families in 9 arthropod orders during this studies in all the locations and seasons. Diptera was the highest insect order collected with 61.05% followed by Coleoptera that was 20.14%. Hymenoptera was 18.03 as the other non necrophagous groups were only 0.77%. The highest number of insects collected was 2230 at the Falcorp mangrove Park, Ijala during the wet season and the least was 809 at Echiki Neke during the dry season. The highest number of insect species collected was 54 on the carrions transferred from the College of Education to the Falcorp during the wet season while the least was 29 in the College of Education, Warri during the dry season. The Dominance index was highest (0.4600) in the College of Education during the dry season but was lowest (0.2742) in the Falcorp during the wet season. Shannon Weiner index was highest (1.3390) in the Falcorp during the dry season but lowest (0.8979) in Echiki during the dry season. Simpson index was highest (0.7258) in the Falcorp during the dry season and lowest (0.5400) in the College during the dry season. Evenness index was highest (0.9843) in Echiki Neke during the dry season and lowest (0.8182). There was no significant difference (P>0.05) among the number of insects collected in the stages of decay across all the locations. In the wet season the one way ANOVA for insects across stages of decay shows significant difference (P<0.05) during the decay in all the locations except in the College. The comparison of the number of insects species during the dry season across locations revealed significant difference (P<0.05) between number of insects species during the wet and dry seasons in the Falcorp and on the carrions transferred from the College to the Falcorp. In all the studies, Chrysomya albiceps, Lucilia sericata, Sarcophaga inzi and Musca domestica were ubiquitous while Cynomyopsis cadaverina, Calliphora vomitoria, Thanatophilus sinuatus were selective in regions season and location. Most of the insects recorded in the Falcorp were also recorded in the College of Education but C. vomitoria, Drosophilia sp, Hydrotae spinigera, Fannia canicularis, Necrobia ruficolis and Camponotus sericeus that were not originally at the Falcorp were brought along with the transferred carrions. The presence of these insects species at the Falcorp were indicators that the carrions have been transferred from the College to the Falcorp. Establishment of the data of insects of forensic importance is very essential tool in the application of these insects in the determination of of the cause, time and place of death. The proper identification of these insects is very crucial element in the field of forensic entomology. Investigators that becomes familiar with human pig carrions will be able to provide forensic entomological evidence that will yield the maximum amount of information possibly needed to reveal hidden truth about a certain crime.