Predicting Geographic Distribution of Forensically Significant Blow Flies of Subfamily Chrysomyinae (Diptera: Calliphoridae) in Northern Thailand

Spatio-Temporal Influence on the Distribution of Forensically Relevant Blowflies (Diptera: Calliphoridae) in Gyeongsangnam-do, South Korea

The study of blowfly (Diptera: Calliphoridae) biodiversity and distribution is crucial for forensic investigations. Abiotic and biotic factors, such as season and habitat type, have a significant impact on blowfly populations. However, only a few forensic entomology studies have been conducted in South Korea, particularly in the Gyeongsangnam-do region. To address this, an extensive year-long survey was conducted to analyze the compositions, habitat preferences, distribution, and seasonal abundance of forensically relevant blowflies in urban and forested habitats of Gyeongsangnam-do, with sampling conducted twice a month using mouse carcass-baited traps set for 48 h each time. A total of 3470 adult blowflies were recorded, encompassing five genera and 13 species, with a noted absence of specimens during the winter months. The predominant species was Lucilia porphyrina, accounting for 37.2% of the total sample, followed by Chrysomya pinguis (27.6%), Lucilia sericata (7.6%), and Lucilia illustris (7.1%). The species composition was consistent across all surveyed regions; however, seasonal variation in species diversity was evident, with a peak in spring and a decline in summer. Notably, certain species exhibited clear preferences for either urban (Calliphora calliphoroides and L. sericata) or forested habitats (L. porphyrina and Ch. pinguis). This pioneering study elucidates the diverse blowfly communities in Gyeongsangnam-do, highlighting significant seasonal and habitat-dependent variations. These findings enrich our understanding of blowfly ecology in this region, offering valuable insights for forensic applications and underscoring the necessity for ongoing entomological surveillance and research.

Geographical Distribution and Multimethod Species Identification of Forensically Important Necrophagous Flies on Hainan Island

Forensic entomology offers unique advantages for the minimum postmortem interval (PMImin) estimation of decomposed corpses in forensic investigations. Accurate species identification and up-to-date locality information are essential. Hainan Island has a tropical rainforest climate and a vast territory. In this study, the community structure of necrophagous flies on Hainan Island was investigated in detail according to geographical environment. The results showed that the dominant species included C. megacephala, S. peregrina, C. rufifacies, S. misera, H. ligurriens, S. sericea, S. cinerea, S. dux, C. pinguis, and M. domestica. Furthermore, C. rufifacies and C. villeneuvi were found only in the high-altitude areas of Wuzhi Mountain, while S. cinerea was distributed only in coastal areas; the latter is a representative species of Hainan Island and has not been reported before. Furthermore, a GenBank database of forensically important flies was established, whilst a high-resolution melt (HRM) curve analysis was applied to identify the common species of Hainan Island for the first time. This study enriches the database of forensically important flies in tropical rainforest regions.

Decomposition and dipteran succession on buried rabbits carcasses

The rabbit carcasses used in this study were buried at depths of 20 and 40 cm, were examined to construct a fly succession database on buried carrion in Riyadh, Saudi Arabia. Twenty-four rabbits were buried, 12 at 20 cm and 12 at 40 cm. One carcass at each depth was exhumed at 10-day intervals up to 120 days. The degradation rate varied among the carcasses. Differences in species and their colonization were also found in the superficial and exhumed carcasses. Eleven species of flies were recorded on carcasses interred at a depth of 20 cm and seven species at 40 cm, while 13 species were recorded on the carcasses over the top of the soil. Species Rhyncomya sp (Diptera: Calliphoridae), Sarcophaga dux Thomson, and Dolichotachina marginella (Wiedemann) (Diptera: Sarcophagidae) were dominant at both depths, while Chrysomya albiceps (Wiedeman), Chrysomya rufifaces (Macquart) (Diptera: Calliphoridae), Musca domestica Linnaeus, and Musca sorbens Wiedemann (Diptera: Muscidae) were dominant in surface carcasses. Megaselia scalaris (Loew) ((Diptera: Phoridae) is a common and typical forensic indicator that was found in the decay/advanced decay and dry stages at a depth of 20 cm. These findings are possibly useful in forensic investigations involving buried bodies in Riyadh, Saudi Arabia.

Chrysomya pinguis (Walker) (Diptera: Calliphoridae), blow fly of forensic importance: A review of bionomics and forensic entomology appraisal

Role of blow flies as the entomological evidence used in forensic investigations has risen dramatically worldwide. As the diverse habitats of Thailand suitably endowed with biodiversity of insects, blow flies of forensic importance need investigation in their bionomics, which are further applied in forensic investigations. Chrysomya pinguis (Walker, 1858) (Diptera: Calliphoridae) make up one of the most common blow fly species found associated with the human corpses and/or death scenes in several countries of the Asia continent. Given the major species as forensically important, this review is performed by the need for gathering information of C. pinguis from literature search in the future application in the regions where this species exists. This review deals with morphology, current knowledge on bionomics and forensic entomology involvement. Important morphological characteristics of egg, larva, puparium and adult were highlighted with illustration and/or micrographs. Search pertaining to molecular analysis used for fly identification and developmental rate of larvae were included. Furthermore, we outline potential issues and challenges of C. pinguis research that necessitate forensic applications in the future.

A preliminary study on the distribution of necrophagous flies on Hainan Island, China

To date, there have been no studies on necrophagous fly populations on Hainan Island in China. Thus, we investigated the species composition of necrophagous flies as well as their geographic distribution on Hainan Island for the first time. Ten sites in different climatic regions across the island were sampled for 7 days per location from November 1, 2018 to February 28, 2019 and from July 1, 2019 to October 31, 2019. Bottle traps made of 1.5 L soft plastic bottles were used to trap necrophagous flies. The collected individuals were identified to species. The specimens represented 5 families and 28 species. Chrysomya megacephala (Fabricius, 1794) was the most dominant species, followed by Chrysomya rufifacies (Macquart, 1843), Hemipyrellia ligurriens (Wiedemann, 1830), Boettcherisca peregrine (Robineau-Desvoidy, 1830), Parasarcophaga dux (Thomson, 1868), Parasarcophaga misera (Walker, 1849), Synthesiomyia nudiseta (Wulp, 1883), and Ophyra chalcogaster (Wiedemann, 1924). The largest collection of flies was obtained in the semiarid region. Species richness was highest in the subhumid region and was higher in summer than in winter, but there were exceptions, such as L. hainanensis (Fan,1965), Boettcherisca formosensis (Lopes, 1961), and Muscina stabulans (Fallen, 1817). Fannia pusio (Wiedemann, 1830), and Boettcherisca formosensis (Lopes, 1961) were newly recorded species on Hainan Island. Of the necrophagous flies collected during the study, we propose several predominant species based on the criteria of distribution, occurrence frequency, and resource preference. Our results not only investigate necrophagous flies on Hainan Island but also accumulate data for criminal investigations in the region.

Exploring microbial communities, assessment methodologies and applications of animal's carcass decomposition: a review

Animals are an essential part of the ecosystem, and their carcasses are the nutrient patches or hotspots where nutrients accumulate for a long time. After death, the physical and chemical properties undergo alterations inside the carcass. The animal carcass is decomposed by many decomposers such as bacteria, fungi, microeukaryotes and insects. The role of microbial symbionts in living organisms is well explored and studied, but there is a scarcity of knowledge and research related to their role in decomposing animal carcasses. Microbes play an important role in carcass decomposition. The origins of microbial communities associated with a carcass, including the internal and external microbiome, are discussed in this review. The succession and methods used for the detection and exploration of decomposition-associated microbial communities have been briefly described. Also, the applications of carcass-associated microbial taxa have been outlined. This review is intended to understand the dynamics of microbial communities associated with the carcass and pave the way to estimate postmortem interval and its role in recycling nutrients.

Microbiome in Death and Beyond: Current Vistas and Future Trends

Forensic medicine has, for a long time, been relying on biochemical, anthropologic, and histopathologic evidences in solving various investigations. However, depending on the method used, lengthy sample processing time, scanty sample, and less sensitivity and accuracy pervade these procedures. Accordingly, newer arenas such as the thanatomicrobiome have come forward to aid in its quandaries; furthermore, the parallel advances in genomic and proteomic techniques have complemented and are still emerging to be used in forensic experiments and investigations. Postmortem interval (PMI) is one of the most important aspects of medico-legal investigations. The current trend in PMI estimation is toward genomic analyses of autopsy samples. Similarly, determination of cause of death, although a domain of medical sciences, is being targeted as the next level of forensic casework. With the current trend in laboratory sciences moving to the discovery of newer disease-specific markers for diagnostic and prognostic purposes, the same is being explored for the determination of the cause of death by using techniques such as Real-Time PCR, DNA micro-array, to Next-Gen Sequencing. Establishing an individual’s biological profile has been done using medicolegal methods and anthropology as well as bar-bodies/Davidson bodies (gender determination); and in cases where the determination of age/gender is a challenge using morphological characteristics; the recent advances in the field of genomics and proteomics have played a significant role, e.g., use of mitochondrial DNA in age estimation and in maternity disputes. The major hurdle forensic medical research faces is the fact that most of the studies are conducted in animal models, which are often difficult to mimic in human and real-time scenarios. Additionally, the high accuracy required in criminal investigations to be used in a court of law as evidence has prevented these results to come out of the labs and be used to the optimum. The current review aims at giving a comprehensive and critical account of the various molecular biology techniques including “thanatogenomics,” currently being utilized in the veritable fields of forensic medicine.

Temperature-dependent development of the blow fly Chrysomya pinguis and its significance in estimating postmortem interval

Chrysomya pinguis (Walker) (Diptera: Calliphoridae) is an endemic Asiatic blow fly species of forensic importance. Chrysomya pinguis is one of the first species to colonize a corpse, especially in high altitude areas during spring and autumn when the ambient temperature is lower. Despite its potential for forensic investigations to estimate the minimum postmortem interval (PMImin), little is known about the development of C. pinguis. In this study, C. pinguis was collected from the Yangtze River Delta region of China and reared at seven constant temperatures between 16°C and 34°C to investigate the effect of temperature on development duration, accumulated degree hours and larval body length of C. pinguis. Isomorphen and isomegalen diagrams for C. pinguis were generated using the results, and equations describing the variation in larval body length during development and the temperature-induced variation in development time were also obtained. Chrysomya pinguis can complete its life cycle at 16-34°C. The mean (±s.d.) developmental durations of C. pinguis from egg to adult at 16°C, 19°C, 22°C, 25°C, 28°C, 31°C and 34°C were 811.0 ± 3.8, 544.8 ± 2.0, 379.8 ± 1.8, 306.7 ± 2.4, 250.0 ± 2.8, 203.2 ± 2.1 and 185.3 ± 1.6 h, respectively. The mean (±s.e.) developmental threshold temperature D0 and the thermal summation constant K of the whole developmental process of C. pinguis were estimated as 10.88 ± 0.21°C and 4256.50 ± 104.50 degree hours, respectively. This study provides fundamental development data for the use of C. pinguis to estimate PMImin.

A eukaryotic community succession based method for postmortem interval (PMI) estimation of decomposing porcine remains

Recent, short-term studies on porcine and human models (albeit with few replicates) demonstrated that the succession of the microbial community of remains may be used to estimate time since death. Using a porcine model (N=6) over an extended period of time (1703 ADD, or two months), this study characterized the eukaryote community of decomposing remains. Skin microbial samples were collected from the torso of each set of remains every day during the first week, on alternate days during the second week, and once a week for the remainder of the 60-day period; all collection intervals were recorded in accumulated degree days (ADD). The eukaryote community of each sample was determined using 18S ribosomal DNA (rDNA) MiSeq high throughput sequencing; data were analyzed in the Mothur pipeline (v1.39.5) and in IBM SPSS and R statistical packages. The relative abundance of eukaryote taxa across ADD/Days and an Analysis of Molecular Variance (AMOVA) indicated similarities between sequential ADD/Days, but significant differences in the eukaryote communities as broad stage 'milestones' of decomposition were reached. Fresh remains (0-57 ADD/0-2 Days; exhibiting a total body score (TBS) of 0-10) were characterized by the combined presence of Saccharomycetaceae, Debaryomycetaceae, Trichosporonaceae, Rhabditida, and Trichostomatia. During bloat and active decay (87-209 ADD/3-7 Days; exhibiting TBS of 11-20), Diptera was the most abundant eukaryotic taxa. During advanced decay stage (267-448 ADD/9-15 Days; exhibiting TBS of 21-25), Rhabditida was the most dominant eukaryote. Dry/skeletal remains (734-1703 ADD/26-61 Days; TBS≥26) were dominated by fungal families Dipodascaceae, Debaryomycetaceae, Trichosporonaceae, and Sporidiobolaceae. Using the family-level eukaryote taxonomic data for the entire study, random forest modelling explained 89.58% of the variation in ADD/Days, with a root mean square error (RMSE) of 177.55 ADD (≈6 days). Overall, these results highlight the importance of the microbial eukaryote community during the process of decomposition and in estimation of PMI.

Spatial Distribution of Forensically Significant Blow Flies in Subfamily Luciliinae (Diptera: Calliphoridae), Chiang Mai Province, Northern Thailand: Observations and Modeling Using GIS

Blow flies of the subfamily Luciliinae (Diptera: Calliphoridae) are one of the main forensically important subfamilies globally. In addition to being used to estimate the minimum post-mortem interval (PMI_min), assuming colonization occurred after death, blow fly specimens found infesting a human corpse are used to determine if the corpse was relocated or if the individual ingested narcotics prior to death. The presence of these blow flies in a given area is strongly influenced by abiotic and biotic factors, such as temperature, elevation, and habitat. Having this information, along with geographical distributions and the characteristics of preferred habitats, is necessary to better understand the biology of this group. This study aimed to characterize the spatial distribution of Luciliinae throughout 18 sampling sites within six ecozones (disturbed mixed deciduous forest, mixed deciduous forest, mixed orchard, paddy field, lowland village, and city/town) in central Chiang Mai Province, northern Thailand over one year (May 2009–May 2010). The purpose of the study was to elucidate the relationship of blow fly species composition with environmental abiotic factors (e.g., temperature, relative humidity, light intensity), and to predict the distribution of the common species within this subfamily using GIS. Adult collections were performed biweekly, baited with one-day-old beef offal. A total of 2331 Luciliinae flies trapped, comprising eight species, of which the four predominant species were Hemipyrellia ligurriens (Wiedemann) (n = 1428; 61.3%), Lucilia porphyrina (Walker) (n = 381; 16.3%), Hemipyrellia pulchra (Wiedemann) (n = 293; 12.6%), and Lucilia papuensis Macquart (n = 129; 5.5%). Population density across species varied seasonally, peaking in August 2009 coinciding with the rainy season. Predicting population composition was based on a model developed with ArcGIS 9.2, which utilized environmental variables (temperature, relative humidity, and light intensity) in conjunction with abundance data. Models indicated H. ligurriens had the most widespread geographic distribution, while H. pulchra was predicted to occur largely in mixed orchards and lowland villages. Lucilia porphyrina and L. papuensis were less widespread, restricted mainly to mixed deciduous forest. This model, along with knowledge of forensic information, may be useful under certain investigations where the corpse may have been relocated.