This paper discusses the colonization of the stratiomyid species Ptecticus melanurus (Walker) (Diptera: Stratiomyidae) in monkey carrion and its potential for the determination of the minimum time since death (PMI). A study was conducted in a tropical forest at Bangi, Malaysia from 13 November 2009 to 8 June 2011. Twelve monkey carcasses (Macaca fascicularis Raffles) were used and divided in equal number into three different field trials. Adults of P. melanurus were first observed on monkey carrions on the second day the carcasses were placed in the field while their penultimate instar larvae were found in the wet soil under and beside carcass from day 8 to 31 days postmortem.
This study was carried out in an oil palm plantation in Bandar Baharu, Kedah using monkey carcasses and focuses in documenting the decomposition and dipteran colonization sequences in 50 days. This is the first study of Diptera associated with the exploitation of carcasses conducted in the north of peninsular Malaysia during the dry and wet seasons thereat. During the process of decomposition in both seasons, five phases of decay were recognized namely fresh, bloated, active decay, advance decay and dry remain. In this decomposition study, biomass loss of carcass occurred rapidly during the fresh to active decay stage due to the colonization and feeding activity of the Diptera larvae. The duration of the fresh and bloated stages of decay were the same in wet and dry seasons but later stages of decay were markedly shorter during the wet season. Twenty one species of adult Diptera were identified colonizing carcasses in the study period. Among the flies from the family Calliphoridae, Chrysomya megacephala Fabricius and Chrysomya nigripes Aubertin were recognized as the earliest arrivals on the first day of exposure. Adult Ch. nigripes was abundant for approximately two weeks after placement of the carcasses. By comparing the percentages of adults collected during the study period, the calliphorids abundance in percentages in wet season was 50.83%, but in dry season, the abundance was only about 35.2%. In contrast, the percentage of Sphaeroceridae in wet season was only 3.33%, but in the dry season, the abundance was 20.8%. Dipteran in family Phoridae, Piophilidae, Sepsidae, Drosophilidae and Dolichopodidae colonized the carcasses for a long period of time and were categorized as long term colonizers.
Decomposing carrion provides a temporary microhabitat and food source for a distinct community of organisms. Arthropods constitute a major part of this community and can be utilized to estimate the postmortem interval (PMI) of cadavers during criminal investigations. However, in Malaysia, knowledge of carrion arthropod assemblages and their succession is superficial. Therefore, a study on three types of forensic entomology animal model was conducted from 27 September 2010 to 28 October 2010 in a tropical rainforest at National University of Malaysia, Bangi, Selangor, Malaysia. Over one month collections of arthropods were made on nine animal carcasses: three laboratory rats (Rattus norvegicus, mean weight: 0.508 ± 0.027 kg), three rabbits (Oryctolagus cuniculus, mean weight: 2.538 ± 0.109 kg) and three long tailed macaque (Macaca fascicularis, mean weight: 5.750 ± 0.551 kg). A total of 31,433 arthropods belonging to eight orders and twenty-eight families were collected from all carcasses. Among 2924 of adults flies collected, approximately 19% were calliphorids with Chrysomya megacephala (Fabricius, 1794) being the most abundant. Arthropod taxon richness was lower on rat carcasses compared to that of rabbit and monkey carcasses, and this was more apparent during the first week of decomposition. However, there were no significant differences in Shannon-Weiner index (H'), Simpson dominance index (C) and Pielou's Evenness index (J) between different animal model. The arthropod assemblages associated to animal model were different significantly (p<0.05) while decomposition stage was a significant factor influencing insect assemblages (p<0.05). Analysis on the arthropods succession indicated that some taxa have a clear visitation period while the others, particularly Coleoptera, did not show a clear successional pattern thus require futher insect succession study. Although human bodies were not possible for the succession study, most of the arthropods collected are necrophagous, and will also possibly colonize human cadaver, and potentially be useful in assisting in estimates of PMI in future forensic cases in Malaysia.