The Influence of Clothing and Wrapping on Carcass Decomposition and Arthropod Succession During the Warmer Seasons in Central South Africa*

Abstract: The influence of clothing and wrapping on carcass decomposition and arthropod succession was investigated to provide data to enable estimated postmortem interval in homicide investigations. Six pig carcasses, Sus scrofa, were divided into three sample groups, each with a clothed carcass wrapped and a carcass wrapped with no clothes. Two more carcasses, one with no clothes or wrapping, the other with clothes and no wrapping were used as controls. The clothed or wrapped carcasses had larger visible maggot masses, which moved more freely and these carcasses took longer to dry out. The blow fly maggot masses were dominated by Chrysomya marginalis and Chrysomya albiceps. Oviposition occurred simultaneously on all carcasses. High temperatures in one case caused significant maggot mortality. The Coleoptera community was dominated by Silphidae, Thanathopilus micans larvae, Dermestidae, Dermestes maculatus adults and larvae, and Cleridae, Necrobia rufipes.     

Preliminary Observations of Arthropods Associated with Buried Carrion on Oahu

Several studies in Hawaii have focused on arthropod succession and decomposition patterns of surface remains, but the current research presents the first study to focus on shallow burials in this context. Three domestic pig carcasses (Sus scrofa L.) were buried at the depths of 20–40 cm in silty clay loam soil on an exposed ridge on the leeward side of the volcanically formed Koolau Mountain Range. One carcass was exhumed after 3 weeks, another after 6 weeks, and the last carcass was exhumed after 9 weeks. An inventory of arthropod taxa present on the carrion and in the surrounding soil and observations pertaining to decomposition were recorded at each exhumation. The longer the carrion was buried, the greater the diversity of arthropod species that were recovered from the remains. Biomass loss was calculated to be 49% at the 3‐week interval, 56% at the 6‐week interval, and 59% at the 9‐week interval.     

Associational Patterns of Scavenger Beetles to Decomposition Stages

Beetles associated with carrion play an important role in recycling organic matter in an ecosystem. Four experiments on decomposition, one per season, were conducted in a semirural area in Bahía Blanca, Argentina. Melyridae are reported for the first time of forensic interest. Apart from adults and larvae of Scarabaeidae, thirteen species and two genera of other coleopteran families are new forensic records in Argentina. Diversity, abundance, and species composition of beetles showed differences between stages and seasons. Our results differed from other studies conducted in temperate regions. Four guilds and succession patterns were established in relation to decomposition stages and seasons. Dermestidae (necrophages) predominated in winter during the decomposition process; Staphylinidae (necrophiles) in Fresh and Bloat stages during spring, summer, and autumn; and Histeridae (necrophiles) and Cleridae (omnivores) in the following stages during those seasons. Finally, coleopteran activity, diversity and abundance, and decomposition rate change with biogeoclimatic characteristics, which is of significance in forensics.     

A Preliminary Study of Insect Succession in Al‐Ahsaa Oasis,in the Eastern Region of the Kingdom of Saudi Arabia

Rabbit carcass decomposition was examined in four seasons in Al‐Ahsaa Oasis. Decomposition rate was significantly faster in summer compared with other seasons. Fourteen insect species from four orders and seven families were recorded: Calliphoridae, Muscidae, Sarcophagidae, Formicidae, Histeridae, Dermestidae, and Tenebrionidae. Most of the fly maggots collected were Calliphoridae with only one species from both Muscidae and Sarcophagidae. Maggots of Calliphora vicina (R.‐D.) and Chrysomya albiceps (Wiedemann) colonized the carcasses in all seasons while both Ch. bezziana (Villeneuve) and Lucilia sericata (Meigen) were found in all seasons except for winter. Maggots of Chrysomya megacephala (F.) and Phormia regina (Meigen) were only collected in the summer and autumn, respectively. Four coleopteran species were collected: Hymenorus sp., Saprinus chacites (Illiger), Dermestes maculatus DeGeer and Blaps sp. One formicidian species, Pheidole megacephala (F.), was observed in all seasons. Insect richness was greater, and decomposition rate was faster in summer compared with other seasons.     

Diel Activity and Effect of Carcass Decomposition on the Attractiveness to the Forensically Important Species Oxelytrum Discicolle (Coleoptera: Silphidae)†

Oxelytrum discicolle is a carrion beetle commonly found in the Neotropical region, mainly associated with cadavers and carcasses. Information on behavior related to the likelihood of cadaver colonization is scarce. We performed two field experiments in peri‐urban forest in Brazil in order to strengthen our knowledge on O. discicolle behavior. In the first experiment, we assessed the preference for piglet carcasses at different stages of decomposition offered simultaneously in two seasons, dry and rainy, while in the second experiment we investigated the diel activity of adults. A total of 493 adults were collected in the experiments. A significantly higher abundance was detected in the rainy season. There was a marked preference for carcasses at advanced stages. Adults exhibited a typical nocturnal behavior, the number trapped at night was 17 times greater than those collected during the day. Oxelytrum discicolle is nocturnal species that prefers carcasses in advanced stage of decomposition.     

Potential Use of Bacterial Community Succession in Decaying Human Bone for Estimating Postmortem Interval,,

Bacteria are taphonomic agents of human decomposition, potentially useful for estimating postmortem interval (PMI) in late‐stage decomposition. Bone samples from 12 individuals and three soil samples were analyzed to assess the effects of decomposition and advancing time on bacterial communities. Results indicated that partially skeletonized remains maintained a presence of bacteria associated with the human gut, whereas bacterial composition of dry skeletal remains maintained a community profile similar to soil communities. Variation in the UniFrac distances was significantly greater between groups than within groups (p < 0.001) for the unweighted metric and not the weighted metric. The members of the bacterial communities were more similar within than between decomposition stages. The oligotrophic environment of bone relative to soft tissue and the physical protection of organic substrates may preclude bacterial blooms during the first years of skeletonization. Therefore, community membership (unweighted) may be better for estimating PMI from skeletonized remains than community structure (weighted).     

Arthropods of Forensic Importance on Pig Carrion in the Coahuilan Semidesert,Mexico

Abstract: This is the first report of an ongoing research to establish a sarcosaprophagous arthropod database in the Coahuilan semidesert. Seven pigs (Sus scrofa L.) were used as human models to determine succession in an open urban area during the 2007 winter–spring period. Arthropods were collected manually and from pitfall traps. Carcass biomass loss, as well as arthropod colonization, was recorded during 71 days postmortem. Five decomposition stages were identified during which most abundant orders were found to be Diptera, Coleoptera, and Hymenoptera. Lucilia sericata (Meigen), Chrysomya rufifacies (Macquart), Necrobia rufipes (DeGeer), Dermestes maculatus (DeGeer), Pheidole hyatti Emery, and Pogonomyrmex rugosus Emery stood out as dominant species.     

Comparison of Decomposition Rates and Faunal Colonization of Carrion in Indoor and Outdoor Environments

Abstract: Decomposition and insect colonization of pig (Sus scrofa L.) carcasses were observed over a 42‐day period inside and outside a house in a suburban region of Edmonton, Alberta. Three freshly killed pig carcasses were placed outdoors on grass and three carcasses were placed in separate rooms inside a house in a suburban residential area. The carcasses were examined and sampled regularly. Outside carcasses were colonized rapidly by Calliphora vicina (R‐D), Lucilia sericata (Meigen), Lucilia illustris (Meigen), Eucalliphora latifrons (Hough), Cynomya cadaverina (R‐D), Phormia regina (Meigen), and Protophormia terraenovae (R‐D). There was a delay of 5 days before inside carcasses were first colonized but all species except E. latifrons and L. illustris readily colonized at this time. Many more insects colonized the outside carcasses, and these were rapidly skeletonized. Inside, much fewer insects were present and decomposition was slowed and colonization extended. Dispersal patterns of postfeeding larvae inside the house on hard substrate were greatly expanded compared with those from carcasses on grass.     

Comparative Analysis of Insect Succession Data from Victoria (Australia) Using Summary Statistics versus Preceding Mean Ambient Temperature Models

Minimum postmortem interval (mPMI) can be estimated with preceding mean ambient temperature models that predict carrion taxon pre‐appearance interval. But accuracy has not been compared with using summary statistics (mean ± SD of taxon arrival/departure day, range, 95% CI). This study collected succession data from ten experimental and five control (infrequently sampled) pig carcasses over two summers (n = 2 experimental, n = 1 control per placement date). Linear and exponential preceding mean ambient temperature models for appearance and departure times were constructed for 17 taxa/developmental stages. There was minimal difference in linear or exponential model success, although arrival models were more often significant: 65% of linear arrival (r² = 0.09–0.79) and exponential arrival models (r² = 0.05–81.0) were significant, and 35% of linear departure (r² = 0.0–0.71) and exponential departure models (r² = 0.0–0.72) were significant. Performance of models and summary statistics for estimating mPMI was compared in two forensic cases. Only summary statistics produced accurate mPMI estimates.     

Quantifying the Temperature of Maggot Masses and its Relationship to Decomposition

Numerous Calliphoridae species have been observed to form larval aggregations during the feeding stage of development, resulting in localized increases in temperature. This study investigates the relationship between maggot numbers in a mass and heat generation. Single‐species aggregations (Lucilia sericata) of various sizes (50–2500 individuals) were reared in the laboratory at a constant ambient temperature of 22°C. Internal mass temperatures were recorded every 5 min throughout the feeding stage of development. Results showed that mass temperatures increased with mass numbers (p‐value < 0.001), ranging from 2.5 to 14°C above ambient. A minimum mass size of 1200 produced overall temperatures that were significantly warmer than ambient, diverging away from 22°C after c. 26 h. These results indicate that the microclimate of a mass has the potential to differ significantly from ambient, which may be influencing larval development rates and should therefore be factored into mPMI estimates to increase accuracy.     

A Checklist of Calliphoridae Blowflies (Insecta,Diptera) Associated with a Pig Carrion in Central Brazil*

Abstract: Although the Cerrado is the second major Brazilian biome, few studies have been undertaken about its entomofauna. Blowflies have an important role in forensic entomology, helping in the determination of postmortem intervals. The main goal of this exploratory study was to identify and to catalog the blowfly species associated with a pig carcass. The study was conducted in a pasture in Brasília, Distrito Federal. A pig (Sus scrofa) was killed with a .22 caliber shot in the frontal region of the head. Adult blowflies were surveyed daily from June 1 through 30, 2004. A total of 14,910 adult calliphorids were collected, representing eight species: Chrysomya albiceps, C. megacephala, Cochliomyia macellaria, Chloroprocta idioidea, Hemilucilia semidiaphana, H. segmentaria, Lucilia cuprina, and L. eximia. C. albiceps was the most frequent species, amounting to 94.76% of the catch. Five decomposition stages were observed, and for calliphorids, the most attractive stage was the bloated one.     

Human Cutaneous Myiasis by the Australian Sheep Blowfly,Lucilia cuprina (Diptera: Calliphoridae), in Oklahoma

This case report describes an incident of myiasis in Oklahoma City, Oklahoma. Paramedics treated a 53‐year‐old man in the field when he suffered cardiac arrest. He was intubated by the paramedics and transported to an emergency room, where he received two stents and a balloon pump. He was found to have a GCS of three and remained in the hospital for 7 days before passing away. After his death, the breathing tube was removed, revealing the presence of several maggots. On closer inspection, the dipteran larvae were found in both the oral and nasal cavities. Four of these larvae were reared to adulthood and identified as Lucilia cuprina (Weidemann) (Diptera: Calliphoridae), commonly known as the Australian sheep blowfly, by the Biology Department of the University of Oklahoma. Based on the fly's life cycle and rate of development, the infestation is suspected to be hospital acquired.     

Soft Tissue Decomposition of Submerged,Dismembered Pig Limbs Enclosed in Plastic Bags*

Abstract: This study examines underwater soft tissue decomposition of dismembered pig limbs deposited in polyethylene plastic bags. The research evaluates the level of influence that disposal method has on underwater decomposition processes and details observations specific to this scenario. To our knowledge, no other study has yet investigated decomposing, dismembered, and enclosed remains in water environments. The total sample size consisted of 120 dismembered pig limbs, divided into a subsample of 30 pig limbs per recovery period (34 and 71 days) for each treatment. The two treatments simulated non‐enclosed and plastic enclosed disposal methods in a water context. The remains were completely submerged in Lake Ontario for 34 and 71 days. In both recovery periods, the non‐enclosed samples lost soft tissue to a significantly greater extent than their plastic enclosed counterparts. Disposal of remains in plastic bags therefore results in preservation, most likely caused by bacterial inhibition and reduced oxygen levels.     

A Forensic Entomological Analysis Can Yield an Estimate of Postmortem Interval,and Not Just a Minimum Postmortem Interval: An Explanation and Illustration Using a Case

Several authors claimed that a forensic entomological analysis can never be interpreted as the postmortem interval (PMI), but that it can be interpreted as a minimum postmortem interval (PMI_min), or dead for not less than X amount of time. Because in most instances, a PMI estimate should be a range, that is, the set of values from maximum postmortem interval (PMI_max) to PMI_min, objections to PMI estimation are objections to PMI_max estimation. The arguments for this position did not address the substantial body of literature describing estimation of both PMI_max and PMI_min using insect succession analysis. This report reviews the scientific issues and presents a recent homicide investigation in which several forensic entomology experts used the absence of carrion insects on the corpse, a kind of succession analysis, to estimate PMI or PMI_max.     

Investigation into Seasonal Scavenging Patterns of Raccoons on Human Decomposition,

Although raccoons are known as one of the most common scavengers in the U.S., scavenging by these animals has seldom been studied in terms of forensic significance. In this research, the seasonal pattern of raccoon scavenging and its effect on human decomposition was investigated using 178 human cadavers placed at the Anthropological Research Facility (ARF) of the University of Tennessee, Knoxville (UTK) between February 2011 and December 2013. The results reveal that (i) the frequency of scavenging increases during summer, (ii) scavenging occurs relatively immediately and lasts shorter in summer months, and (iii) scavenging influences the decomposition process by hollowing limbs and by disturbing insect activities, both of which eventually increases the chance of mummification on the affected body. This information is expected to help forensic investigators identify raccoon scavenging as well as make a more precise interpretation of the effect of raccoon scavenging on bodies at crime scenes.     

Decomposition Rate and Pattern in Hanging Pigs

Accurate prediction of the postmortem interval requires an understanding of the decomposition process and the factors acting upon it. A controlled experiment, over 60 days at an outdoor site in the northwest of England, used 20 freshly killed pigs (Sus scrofa) as human analogues to study decomposition rate and pattern. Ten pigs were hung off the ground and ten placed on the surface. Observed differences in the decomposition pattern required a new decomposition scoring scale to be produced for the hanging pigs to enable comparisons with the surface pigs. The difference in the rate of decomposition between hanging and surface pigs was statistically significant (p = 0.001). Hanging pigs reached advanced decomposition stages sooner, but lagged behind during the early stages. This delay is believed to result from lower variety and quantity of insects, due to restricted beetle access to the aerial carcass, and/or writhing maggots falling from the carcass.     

DNA Barcoding in Forensic Entomology – Establishing a DNA Reference Library of Potentially Forensic Relevant Arthropod Species,

Throughout the years, DNA barcoding has gained in importance in forensic entomology as it leads to fast and reliable species determination. High‐quality results, however, can only be achieved with a comprehensive DNA barcode reference database at hand. In collaboration with the Bavarian State Criminal Police Office, we have initiated at the Bavarian State Collection of Zoology the establishment of a reference library containing arthropods of potential forensic relevance to be used for DNA barcoding applications. CO1‐5P’ DNA barcode sequences of hundreds of arthropods were obtained via DNA extraction, PCR and Sanger Sequencing, leading to the establishment of a database containing 502 high‐quality sequences which provide coverage for 88 arthropod species. Furthermore, we demonstrate an application example of this library using it as a backbone to a high throughput sequencing analysis of arthropod bulk samples collected from human corpses, which enabled the identification of 31 different arthropod Barcode Index Numbers.     

Eristalinus arvorum (Fabricius, 1787) (Diptera: Syrphidae) in Human Skull: A New Fly Species of Forensic Importance

A body of an unknown adult female was found within a shallow burial ground in Malaysia whereas the skull was exposed and visible on the ground. During autopsy examination, nine insect larvae were recovered from the interior of the human skull and subsequently preserved in 70% ethanol. The larvae were greyish in appearance, each with a posterior elongated breathing tube. A week after the autopsy, more larvae were collected at the burial site, and some of them were reared into adults. Adult specimens and larvae from the skull and from the burial site were sequenced to obtain DNA barcodes. Results showed all adult flies reared from the burial site, as well as the larvae collected from the skull were identified as Eristalinus arvorum (Fabricius, 1787) (Diptera: Syrphidae). Here, we report the colonization of E. arvorum larvae on a human corpse for the first time.     

The Effects of Sharp‐Force Thoracic Trauma on the Rate and Pattern of Decomposition

Given the multiple factors that may alter the rate of decomposition, one of the more difficult tasks that anthropologists and pathologists face is determining of the postmortem interval (PMI). While trauma has been widely accepted as being among those factors, recent published studies have contradicted this premise. However, major issues exist with these studies. Consequently, this study was designed to simulate a more realistic setting in an effort to settle this discrepancy in the literature. This study utilized eight porcine remains; three of which received incised wounds penetrating the thoracic cavity, three others received nonpenetrating wounds, and two were designated nontrauma controls. Measurements included evaluating the total body score (TBS) on temporal and accumulated degree days (ADD). Using a two‐way repeated measures ANOVA, the results of this study found that while trauma does have an influence in the pattern of decomposition, it does not influence the rate of decomposition.     

The Influence of Penetrative Trauma on the Rate of Decomposition*†

Abstract: An understanding of the factors affecting decomposition is important for the accurate estimation of postmortem interval. An experimental study on the influence of penetrating trauma on decomposition rate was carried out using the domestic pig, Sus scrofa. The results of this study were: (i) Diptera were preferentially attracted to and oviposited at natural orifices. Trauma sites were not preferentially selected for oviposition; (ii) no differences between trauma and non‐trauma groups were found in time to skeletonization, weight loss (p = 0.906), total body score (p = 0.824), body temperature (p = 0.967), or changes in soil pH (p = 0.684); and (iii) the effect of investigator disturbance was significant when decomposition was measured as weight loss (p = 0.000). This study suggests that penetrating trauma of the type used in this study cannot be considered a major factor in the rate of decomposition and time to skeletonization of a gunshot trauma victim.