The Influence of Insects on Decomposition Rate in Buried and Surface Remains

Journal of Forensic and Legal Medicine, 2020

There is a long history of using insects on a decomposing corpse as an invaluable tool to estimate the minimum postmortem interval (PMI) during death investigations. The present study was carried out to study the decomposition pattern and insects associated with a submerged rabbit (Oryctolagus cuniculus Linnaeus, 1758) carcase. A total of 1795 insect specimens were found to be associated with different decomposition stages. During the submerged fresh stage three species from the genus Chironomus visited the carcase. During the early floating and floating decay stages, insects belonging to Coenagrionidae, Chironomidae, Lestidae, Aeshnidae families along with the aquatic beetles i.e. Enochrus esuriens (Walker, 1858), Regimbartia attenuata (Fabricius, 1801), genus Helochares and Canthydrus laetabilis (Walker, 1858) visited and colonised the carcase. The advanced floating decay and sunken remains stage saw a prominence of Ranatra digitata (Hafiz and Pradhan, 1949), Ranatra filiformis (Fabricius, 1790) and genera Hydroglyphus, Hypoporus, Laccophilus, Berosus and Helochares. The Post-Mortem Submersion Interval (PMSI) was found to be longest in the winters (44 days, ADD = 1066.5) and shortest in the rainy season (16 days, ADD = 405.5) while the spring and the summer season showed a moderate PMSI of 26 days (ADD = 632.5) and 19 days (ADD = 472.5) respectively.

2008

Insects found associated with corpse can be used as one of the indicators in estimating postmortem interval (PMI). The objective of this study was to compare the stages of decomposition and faunal succession between a partially burnt pig (Sus scrofa Linnaeus) and natural pig (as control). The burning simulated a real crime whereby the victim was burnt by murderer. Two young pigs weighed approximately 10 kg were used in this study. Both pigs died from pneumonia and immediately placed in an oil palm plantation near a pig farm in Tanjung Sepat, Selangor, Malaysia. One pig was partially burnt by 1-liter petrol while the other served as control. Both carcasses were visited twice per day for the first week and once thereafter. Adult flies and larvae on the carcasses were collected and later processed in a forensic entomology laboratory. Results showed that there was no significant difference between the rate of decomposition and sequence of faunal succession on both pig carcasses. Both carcasses were completely decomposed to remain stage after nine days. The species of flies visiting the pig carcasses consisted of blow flies (Chrysomya megacephala, Chrysomya rufifacies, Hemipyrellia ligurriens), flesh fly (Sarcophagidae.), muscid fly (Ophyra spinigera), soldier fly (Hermetia illucens), coffin fly (Phoridae) and scavenger fly (Sepsidae). The only difference noted was in the number of adult flies, whereby more flies were seen in the control carcass. Faunal succession on both pig carcasses was in the following sequence: Calliphoridae, Sarcophagidae, Muscidae, Phoridae and lastly Stratiomyidae. However, there was overlap in the appearance of members of these families. Blowflies continued to oviposit on both carcasses. Hence postmortem interval (PMI) can still be estimated from the partially burnt pig carcass.

Environment and Ecology Research, 2019

Succession patterns of arthropods associated with decomposing domestic rabbit (Oryctolagus cuniculus Linnaeus, 1758) were investigated in exposed and sheltered habitats, located at 4 o 53'41.680 "N, 6 o 54'39.127 "E and 4 o 54'19.83"N, 6 o 55'17.36"E respectively, University of Port Harcourt, Nigeria. The decomposition of the six domestic rabbits was observed during the onset of the wet season (1 st March -30 th April 2017) to identify forensically important insects attracted to them and determine temperatures and relative humidity influencing carrion decomposition. Five stages of decomposition: Fresh, bloated, active decay, advanced decay and dry remains stages were observed. The sequence of insect succession followed a distinct pattern: dipteran flies first colonized the rabbit carcasses and were succeeded by coleopterans. A total of 33 species of arthropods, in 23 families and 7 orders were collected. The insect families

Research Square (Research Square), 2023

Forensic entomology is a science that studies insects and other arthropods in relation to forensic investigations. This study aimed to examine the presence of insects on pig and rabbit carcasses buried at two different depths, 100 and 50 cm, respectively, along nine sampling dates to establish an insect succession database on buried cadavers in the north sudanian zone of Burkina Faso. In addition, we investigated whether environmental parameters in uence both the decomposition of buried corpses and the abundance of insects. Nine pigs and nine rabbits were buried at 100 and 50 cm respectively, at two different sites. Carcasses were exhumed after 14, 28, 42, 56, 70, 84, 98, 112 and 126 days of burial, respectively. Approximately 668 larvae, pupae, cocoons and adults of insects were surveyed on the two substrates during the 2020 and 2021 study periods, divided into 5 main orders, Diptera, Coleoptera, Hymenoptera, Dermaptera and Orthoptera. Accarinae and a few spiders were also inventoried. Succession of insects varied with depth. No signi cant difference in soil temperature (P = 0.9; 0.12) between the 50 and 100 cm depths was observed. However, signi cant differences were observed between the temperatures of depths and ambient air (P = 2.3e-07; 0.00027). Necrophagous insects were more abundant on the pig substrate than the rabbit. Our data provided precious information in terms of assessing the postburial interval. Highlights Insect diversity associated with pig and rabbit carcasses buried at different depths Environmental parameters affected the decomposition of buried corpses and the abundance of forensic relevance in the study area. Succession of insects varied with depth the holes for burial Necrophagous insects were more abundant on the pig substrate than the rabbit. Key points Entomofauna and pig and rabbit carcasses decomposition buried-Environmental parameters-Succession of insects-depth the holes for burial-Burkina Faso.

International of Scientific Engineering and Applied Sciences, 2017

When a corpse is exposed to the open air, it is an important source of nutrients for bacteria and insects, both for juvenile stages and for adults. In the process of decomposition of the dead organism, insects occupy a preponderant place by helping to considerably reduce the body mass of the corpse. The objective of this work was to evaluate the contribution of different groups of necrophagous insects in the process of decomposition of a corpse exposed to the open air. To do this, nine pigs, including three controls, were tranquilized and euthanized. The cadavers were exposed to insects (except controls) at three experimental sites at a rate of three per site. During the complete decomposition process, the cadavers were weighed every seven days, from March 17 (d0 = day 0) to June 30, 2016 (d105). Between d0 and d7 post mortem, the early arrival of the Calliphoridae, Muscidae and Sarcophagidae Diptera on cadavers, caused them to lose, on average, between 46.70 and 54.75% of their initial mass. At the end of the post-mortem period, cumulative rates amounted to 56.95 to 67.79% loss of body mass. Between post mortem d14 and the end of the advanced decomposition phase of the cadavers, the Diptera Piophilidae and Stratiomyidae appeared in the same way as the Coleoptera. During this phase, rates ranged from 71.24 to 93.93% loss, while controls lost only 24.96% of their initial mass. From the results obtained, the loss of body mass of the corpses is mainly due to the necrophagous activity of the different groups of insects which succeeded each other.

Forensic Science, Medicine and Pathology, 2019

Hanging is one of the most common methods of suicide, and, although it is known that decomposition and patterns of insect fauna colonization of hanging cadavers differ from those of cadavers decomposing on the ground, these differences have only been sparsely studied in Europe so far. We studied the decomposition and insect colonization patterns of ten pig (Sus scrofa domestica) carcasses in a spruce forest near Neuchâtel, Switzerland, over a 32-day period in summer 2013 (July 1st -August 2nd). Five pig carcasses were suspended horizontally in metal cages one meter above the ground and five carcasses were placed directly on the ground. The species occurrence and abundance of Coleoptera and Diptera recovered from passive pitfall traps and collected manually on the carcasses were recorded. Indicator species of decomposition stages and suspended vs. ground cadavers were identified by Indicator Value (IndVal) analysis. The ground carcasses decomposed significantly faster than the suspended carcasses. Coleoptera and Diptera communities differed significantly over time, between treatment, and the treatment effect varied over time. Diptera were evenly distributed among the two treatments. Coleoptera were more abundant and less differentiated on the ground carcasses and represent better indicators of cadavers decomposing on the soil as well as decomposition stages. Our results suggest possible applications such as evaluating if a hanged cadaver has been dropped to the ground, or inversely if a cadaver first lying on the soil has later been hung to fake a suicide. However differences among studies suggest possible effects of mesoclimate determined by habitat which should be explored further.

Legal Medicine, 2003

The succession of insects is commonly used for estimation of the postmortem interval (PMI). In the warm season there are many insect species, which enable us to estimate the time of death, but in the cold season there are less species. For the estimation of a seasonal pattern, we examined 117 human corpses found in domestic environment during the year 2001. We found three typical 'summer species', active from May until October, three further species active from April until November. One blowfly species (Calliphora vicina) and the family of scuttle flies were active all over the year. These insects may be useful for PMI estimation in winter; however, further research concerning the developmental rate of scuttle flies is required. The distinct seasonal pattern of the early colonizing blowfly species allows to allocate the time of death to a particular time interval even in cases of long PMIs if empty puparia of these insects are found.

Journal of medical entomology, 2018

This study assesses the succession of insects on rabbit carcass. The study was conducted in sunny and shaded sites in the west of Iran during four seasons in 2016 and 2017. Based on the results of this study, various factors such as body size, carcass location, and carcass injury could affect the pattern of insect succession on carcass. In this study, we estimated the elapsed time since death (R2 > 0.98, P = 0.00) based on carcass weight loss during the stages of decomposition and the cubic method. Jaccard analysis was performed to determine the similarity of insect taxa during decomposition of rabbit carrion in two different sites during a period of four seasons. Succession pattern analysis for necrophagous insects in both habitats showed a similarity between bloat and decay stages for each habitat. On the other hand, pairwise similarities in taxa were low at the fresh and dry stages, however increased at bloat and decay stages of decomposition. This study shows that succession ...

Turkish Journal of Parasitology, 2018

Objective: Carrion insects inhabiting the soil play an important role in forensic investigations because they may help to solve both active and cold cases. The aim of this study was to examine the entomofauna of forensic importance in soil samples removed after 13 years from a pig carrion decomposition site. Methods: Soil samples were collected from an old carrion decomposition study site in Bâla, the Ankara Province. Four holes, approximately 40 cm deep and 35 cm width were excavated at the study site. The samples were collected and placed in ventilated cups. Each cup was labeled mentioning the excavation location, time, date, and name of the collector. Insects and their remains found in the soil were collected by sweeping the soil from the specimens using a brush. The insects were morphologically identified. Results: A total of 635 specimens of Calliphoridae, Dermestidae, Cleridae, Staphylinidae, Histeridae, and Formicidae were identified. Flies such as Chrysomya albiceps (Wiedmann, 1819), and beetles such as Dermestes frischii (Kugelan, 1792), Necrobia rufipes (De Geer, 1775), and Creophilus maxillosus (Linnaeus, 1758), were identified as the species. Conclusion: Our results show that soil samples still harbor entomological specimens after 13 years. This study, to the best of our knowledge, was the first of its kind in Turkey. Forensically, important insects and their remains may be identified in the soil long time after the corpse is buried. Consequently, cold cases may be solved using insects.

Journal of Forensic Research, 2012

The National Research Council (NRC) released a report in 2009 discussing the "science" used in forensics. Specifically, the report outlined concerns regarding the state of the forensic sciences and what was needed to raise the level of rigor and reliability of these fields in a court of law. In response to this NRC document, the present paper examined several parameters used in decomposition studies that have implications for forensic entomology. Specifically, this analysis was conducted to determine the degree of repeatability in methods across studies as related to general conclusions drawn in court, entomology and forensic investigations. Forensic entomologists primarily analyze insect evidence recovered from decomposing remains to estimate a portion of the Period of Insect Activity (PIA), which encompasses the time of colonization, to infer a minimum Postmortem Interval (PMI). One method utilized by entomologists relies on succession data from published studies to generate estimates of the minimum PMI of a decedent. For this article, approximately 75 publications on arthropod succession on vertebrate carrion were reviewed for 13 criteria that are known to play instrumental roles in governing this process: 1) animal model, 2) time of actual death, 3) euthanasia method, 4) storage method, 5) storage time, 6) time of removal from storage to placement in the field, 7) time of day remains placed in the field, 8) catalog of arthropods associated with the remains over time 9) time of initial insect contact, 10) time of initial colonization (i.e., arthropod offspring located on the remains), 11) study site, 12) number of replicate carcasses and 13) months and season of study. These criteria were selected as they can directly impact arthropod colonization and succession patterns on vertebrate carrion and are easily recorded. Data indicated that such information is highly fragmented, and that key criteria necessary to repeat studies (a core principle of the scientific method) are often lacking in the published literature. As an example, among the studies included in this analysis, we could not find significant associations between arthropod taxa richness and carcass model or carcass size. In the case of carcass size, island biogeography theory predicts that larger areas/resources will hold higher diversity. We suspect that the high degree of reporting variability in taxonomic resolution and taxa-specific study focus precluded such relationships that have been reported for other disciplines of biology. Consequently, we suggest that, to date, because of these issues there has not been a comprehensive analysis (e.g., meta-analysis) to provide general inference of arthropod succession patterns on carrion to predict a minimum PMI. In order to begin standardizing such studies, we suggest that future research endeavors examining arthropod succession on carrion record detailed data for all of the suggested criteria. Doing so can result in data amassed over time for use in comprehensive and strong meta-analyses. Such results could allow for greater appreciation of variation associated with arthropod succession on carrion.