The Food Preferences of the Blow Fly Lucilia cuprina Offered Human Blood,Semen and Saliva,and Various Nonhuman Foods Sources

As human DNA profiles can be obtained from blow fly artifacts, this study aimed to establish the feeding preferences of Lucilia cuprina (Wiedemann) blow flies when offered human biological fluids and nonhuman food sources. One‐day‐old and 3‐day‐old blow flies of both sexes were simultaneously offered human blood, semen and saliva, pet food, canned tuna and honey, and the number and length of visits documented over 6 h. One‐day‐old flies visited pet food and honey most often, but stayed longest on honey and semen. Three‐day‐old flies visited semen and pet food most often, and stayed longest on these food sources. Blood and saliva were the least preferred options for all flies. Overall, flies preferred dry blood and semen to the wet forms. These findings demonstrate that even when other food sources are available, flies at a crime scene may feed on human biological fluids if present, potentially transferring human DNA.     

The Morphology of Fecal and Regurgitation Artifacts Deposited by the Blow Fly Lucilia cuprina Fed a Diet of Human Blood

Fly feces and regurgitation deposits may be mistaken for bloodstain patterns at a crime scene, potentially compromising event reconstruction and/or misdirecting police resources. In some instances, these artifacts contain sufficient human biological material to generate a full DNA profile, sometimes 2 years after deposition. Clearly, it is important that investigators can make the distinction between artifacts and bloodstains. This study examined 6645 artifacts deposited on a smooth, nonporous surface after Lucilia cuprina were fed human blood. Artifacts were also compared with bloodstains on a variety of other surfaces. Both similarities and differences were found between artifacts and bloodstains, highlighting the need for an identification system to assist personnel with little training in bloodstain pattern analysis. The morphology of the artifacts has been described so that these deposits may be more clearly distinguished from bloodstains, targeted by crime scene personnel as potential sources of human DNA, and/or identified as potential evidence contaminants. Flowcharts have been devised to facilitate the analysis.     

The Use of Forensic Tests to Distinguish Blowfly Artifacts from Human Blood,Semen, and Saliva

This study investigated whether routinely used forensic tests can distinguish 3‐day‐old or 2‐week‐old fly artifacts, produced after feeding on human blood, semen, or saliva, from the biological fluid. Hemastix^®, Hemident^?, and Hemascein^? were unable to distinguish blood from artifacts. Hemastix^® returned false positives from negative controls. ABAcard^® Hematrace^® and Hexagon OBTI could distinguish blood from 3‐day‐old artifacts, but not 2‐week‐old artifacts. Phadebas^® and SALIgAE^® were unable to distinguish saliva from artifacts. RSID^?‐Saliva was able to distinguish saliva from 3‐day‐old artifacts, but not 2‐week‐old artifacts. Semen tests Seminal Acid Phosphatase, RSID^?‐Semen, and ABAcard^® p30 were all able to distinguish semen from 3‐day‐old artifacts, but not 2‐week‐old artifacts. The tests investigated cannot be relied upon to distinguish artifacts from biological fluids. However, if an artifact is identified by its morphology, a positive result may indicate which biological fluid the fly consumed, and this knowledge may prove useful for investigators searching for DNA.     

Alteration of expirated bloodstain patterns by Calliphora vicina and Lucilia sericata (Diptera: Calliphoridae) through ingestion and deposition of artifacts

Abstract: Bloodstain pattern analysis can provide insight into a sequence of events associated with a violent crime. However, bloodstain pattern analysis can be confounded by the feeding activity of blow flies. We conducted two laboratory experiments to investigate the relationships between Lucilia sericata (green bottle fly) and Calliphora vicina (blue bottle fly), expirated bloodstains, and pooled bloodstains on a range of surfaces (linoleum, wallpaper, textured paint). C. vicina and L. sericata changed bloodstain pattern morphology through feeding and defecation. They also deposited artifacts in rooms where blood was not present originally. Chemical presumptive tests (Hemastix^®, phenolphthalein, leucocrystal violet, fluorescein) were not able to differentiate between insect artifacts and bloodstains. Thus, C. vicina and L. sericata can confound bloodstain pattern analysis, crime scene investigation, and reconstruction. Crime scene investigators should be aware of these fundamental behaviors, and the effects that blow flies can have on expirated and pooled bloodstain patterns.     

Morphological Features of Regurgitate and Defecatory Stains Deposited by Five Species of Necrophagous Flies are Influenced by Adult Diets and Body Size

The morphological characteristics of artifacts from five species of necrophagous flies were examined following feeding on several types of diets. Four types of insect stains were produced by each species: regurgitate, defecatory, translocation, and tarsal tracks. Regurgitate was the most frequent type deposited (70.9 ± 2.4%), followed by defecatory (19.8 ± 4.0%), tarsal tracks (8.6 ± 1.2%), and translocation (0.7 ± 0.1%). Artifact shapes, sizes, and color were highly variable and species and diet specific. Calliphora vicina and Sarcophaga bullata consistently deposited the largest artifacts after feeding, whereas Chrysomya rufifacies and Ch. megacephala produced more tarsal tracks than the other species examined. Artifacts with tails were infrequently observed (4.1 ± 0.6% of all stains) but occurred as either defecatory or regurgitate stains. The widely variable morphologies of all types of fly artifacts underscores the view that insect stains cannot be distinguished from human bloodstains based on morphology alone.     

The transfer of human DNA by Lucilia cuprina (Meigen) (Diptera: Calliphoridae)

Blowflies leave deposits, termed artefacts, through the processes of excretion and regurgitation. To date, little consideration has been given to the possibility of adult blowflies consuming biological material and subsequently acting as vectors of human DNA through these artefacts. In this study, Lucilia cuprina (Meigen) (Diptera: Calliphoridae) were fed either human blood or human semen ad libitum and their artefacts were analysed for human DNA content. Samples containing 1, 10, 30 and 50 artefacts were tested. Quantifiable and typeable levels of human DNA were found in samples derived from both food sources, and even in samples containing a single artefact. Semen-derived artefacts contained significantly more human DNA than artefacts produced after a blood meal. Consequently a smaller number of artefacts was required to collect sufficient DNA for genotyping. These findings are forensically important as it provides investigators with another potential source of DNA at a crime scene where a body has been moved, or an attempt has been made to clean up biological material. They also highlight how fly artefacts could potentially contaminate and compromise evidence.     

An Experiment to Characterize the Decomposer Community Associated with Carcasses (Sus scrofa domesticus) on Oahu,Hawaii

Pig (Sus scrofa domesticus) carcasses were decomposed on the soil surface of a terrestrial habitat on the island of Oahu, Hawaii to begin characterizing the decomposer community. Results showed that carcasses can decompose rapidly on Oahu, primarily due to the activity of fly larvae, with ~80% of mass lost by 8 days (~220 ADD) postmortem. Scavenging was conducted exclusively by the small Indian mongoose (Herpestes javanicus), first feeding on larvae then feeding on the remains. Carcasses were habitats of warm temperature, little to no oxygen, slightly acidic/neutral pH, and high sodium concentration. Larval masses selected for a microbial community comprised of multiple bacterial taxa from phyla Firmicutes and Proteobacteria, particularly genera Clostridium, Proteus, and Providencia. These larval masses were well established from 3 to 8 days (~90 to ~220 ADD) postmortem. These data provide helpful, novel insight into the structure and activity of carcass decomposer communities on Oahu.     

Distinction of bloodstain patterns from fly artifacts

Forensic scientists may encounter blood spatter at a scene which may be pure or a mixture of fly artifacts and human bloodstains. It is important to be able to make an informed identification, or at least advanced documentation of such stains since the mechanics of production of fly artifacts are not determinable to the crime scene reconstructionist from regular police forces. We describe three cases in which experiments and crime scene reconstruction led to additional information. Case 1: Above the position of a victim, numerous blood stains of the low-high-velocity type were found. Exclusion of these stains being caused by force (but instead caused by the activity of adult blow flies) by use of the following observations that were confirmed in experiments: (a) sperm-/tadpole-like structure with length > width, (b) random directionality, and (c) mixture of round symmetrical and teardrop shaped stains. Case 2: A reddish spatter field was found on a fan chain two rooms away from the place where a dead woman was found. Localization of the spatter on the bottom end of the surface hinted strongly towards fly activity. Case 3: Double homicide; submillimeter stains were found on a lamp between the two corpses. Activity of flies was less likely compared to alternative scenario of moving lampshade and violent stabbing.     

青岛地区常见嗜尸性蝇种及其季节性分布研究

目的观察青岛地区嗜尸性蝇种季节性演替规律,为死亡时间推断提供参考。方法在室外设立田间观察场所,2012年4月1日开始至2013年4月1日,每月第1天6时放置猪尸,20min后开始观察,至18时,期间每小时观察1次;第3天以后,分别于7时、12时、18时各观察1次。观察时记录尸体上出现的昆虫种类、虫态、数量并采集相应标本,进行分类鉴定。结果可以观察到有嗜尸性蝇类侵袭尸体的月份为4月至11月,共发现3科23种蝇类,其中丝光绿蝇、大头金蝇和亮绿蝇数量位列前三,分别占全部观察数量的40.71%、31.95%和7.12%。丝光绿蝇、大头金蝇中午时段出现的数量显著多于早上和傍晚。一年中各种蝇类在中午出现的数量均多于早上及晚上。4月上旬,蝇类早、晚与中午出现的数量相差显著;而在7、8月份差别较小。大部分嗜尸性蝇种集中在新鲜期和肿胀期。结论本文观察数据可为利用嗜尸性蝇类演替规律进行法医学死亡时间推断,以及建立地区嗜尸性蝇种类数据提供参考。     

A Test of a Recently Devised Method of Estimating Skeletal Age at Death using Features of the Adult Acetabulum

Estimation of age at death from adult skeletal remains is highly problematic, due in great part to interpopulation variability in skeletal age changes. Thorough testing of aging methods is therefore of key importance. A method recently devised by Calce (Am J Phys Anthropol 148 (2012): 11–23) for placing adult skeletons into three broad age at death classes (17–39, 40–64, 65+ years) on the basis of acetabular morphology is tested on a collection of 18–19th century AD skeletons (N = 185) of documented age at death from London. Results showed that 45% were correctly assigned to age class using this method. This compares with 81% reported by Calce on 20th century North American material. This indicates significant interpopulation differences in the relationship between the Calce acetabular variables and age, even between populations of European ancestry. Until the sources of this variation are better understood, caution should be used before applying this method to estimate age in unknown skeletons.     

Effect of Temperature on Six Different Developmental Landmarks within the Pupal Stage of the Forensically Important Blowfly Calliphora vicina (Robineau‐Desvoidy) (Diptera: Calliphoridae)

This study investigates the pupal development times of the blow fly Calliphora vicina, which were studied in the laboratory at six different constant temperatures (15, 20, 23, 25, 28, and 30°C each ± 1°C). Lower thresholds (t_L) for development were estimated from the linear regression of the developmental rates on each temperature. These data have made it possible to calculate the accumulated degree days (ADD) necessary for C. vicina to complete the larval stage and to achieve adult emergence. The minimal duration of development from oviposition to adult emergence was found to be inversely related to temperature. Additionally, six landmarks in pupal development are showed, and for each of the landmarks, the ADD value was calculated for every rearing temperature involved. These data assist in calculating the duration of the pupal stage based on morphological characteristics and would be of great value for future forensic entomological casework.     

Forensic Entomology and the Estimation of the Minimum Time Since Death in Indoor Cases

Eight cases that occurred indoors in which the insects played an important role in the mPMI estimation are presented. The bodies of socially isolated people and old people living alone were discovered in central Italy between June and November. mPMI ranged from a few days to several weeks. Insects were collected during the body recovery and the postmortem. Climatic data were obtained from the closest meteorological stations and from measurements performed on the site. Sarcophagidae and Calliphoridae species were present in 75% of the cases with Lucilia sericata and Chrysomya albiceps collected in 50% of the cases. Chrysomya albiceps was always found in association with Lucilia species. Scuttle flies (Phoridae) were found in 37.5% of the cases, confirming the ability of these species in indoor body colonization. We show that if sealed environment may delay, the insect arrival dirty houses may create the environment where sarcosaprophagous insects are already present.     

Variation in Developmental Time for Geographically Distinct Populations of the Common Green Bottle Fly,Lucilia sericata (Meigen)*

Abstract: Time between death and discovery of remains, or postmortem interval (PMI), can be assessed using blow fly maggot age. Forensic entomologists rely on published, often nonlocal, species‐specific developmental tables to determine maggot age. In a series of common garden experiments, we investigated the developmental rate variation between populations of Lucilia sericata collected from Sacramento, CA, San Diego, CA, and Easton, MA at 16°C, 26°C, and 36°C. For the 16°C trial the time measurement started at egg hatch, while for the higher temperatures the experiment began at oviposition; the wandering stage signified the endpoint for all experiments. The distribution of developmental times differed significantly (ANOVA, p < 0.001) between the three populations within each temperature treatment. We discovered that regional variation of developmental times within a blow fly species exists. This study demonstrates the importance of assembling local population‐specific developmental tables when estimating larval age to determine PMI.     

Species Identification of Cannabis sativa Using Real‐Time Quantitative PCR (qPCR),

Most narcotics‐related cases in the United States involve Cannabis sativa. Material is typically identified based on the cystolithic hairs on the leaves and with chemical tests to identify of the presence of cannabinoids. Suspect seeds are germinated into a viable plant so that morphological and chemical tests can be conducted. Seed germination, however, causes undue analytical delays. DNA analyses that involve the chloroplast and nuclear genomes have been developed for identification of C. sativa materials, but they require several nanograms of template DNA. Using the trnL 3′ exon‐trnF intragenic spacer regions within the C. sativa chloroplast, we have developed a real‐time quantitative PCR assay that is capable of identifying picogram amounts of chloroplast DNA for species determination of suspected C. sativa material. This assay provides forensic science laboratories with a quick and reliable method to identify an unknown sample as C. sativa.     

DNA Barcoding Identifies all Immature Life Stages of a Forensically Important Flesh Fly (Diptera: Sarcophagidae)

Carrion‐breeding insects, such as flesh flies (Diptera: Sarcophagidae), can be used as evidence in forensic investigations. Despite their considerable forensic potential, their use has been limited because morphological species identification, at any life stage, is very challenging. This study investigated whether DNA could be extracted and cytochrome oxidase subunit I (COI) barcode sequences obtained for molecular identification of each immature life stage of the forensically important Australian flesh fly, Sarcophaga (Sarcorohdendorfia) impatiens (Walker). Genomic DNA extracts were prepared from all larval instars and puparia. Amplification of the barcoding region was successful from all extracts, but puparia amplicons were weak. All sequences were identified as S. impatiens with 99.95% confidence using the Barcoding of Life Database (BOLD). Importantly, crop removal was necessary to eliminate PCR inhibition for specimens from late second and early third instars. Similar results are expected for immatures of other carrion‐breeding species, enhancing the use of evidence from immature flies in forensic investigations.     

Investigation of nocturnal oviposition by necrophilous flies in central Texas

The need to accurately estimate the postmortem interval (PMI) has prompted research into factors affecting fly oviposition (i.e., oviposition and/or larviposition) on a corpse. Research efforts have focused on whether or not diurnally active flies oviposit during nighttime hours. This study reports that nocturnal oviposition (defined as occurring between 2100-0600 h CDST (Central Daylight Savings Time)) did not occur on freshly killed white rats or mice, on beef (fresh or aged up to 48 h), on freshly thawed pigs, nor, usually, on thawed pigs that were aged for up to 48 h. Limited oviposition did occur between 2100 and 2120 h on one bloated pig at a lighted rural site. Necrophilous flies were present and active at lighted and dark sites (urban and rural) before and immediately after sunset, but fly activity on the bait ceased within 50 min postsunset and did not resume until after 0600 h. These observations support other studies reporting that diurnally active flies do not oviposit during the nighttime.     

Temperature‐dependent Development of Parasarcophaga similis (Meade 1876) and its Significance in Estimating Postmortem Interval

Flesh flies are commonly found insects on decaying corpses that appears slightly later than blowflies, and their development patterns are significant indicators for minimum postmortem interval (PMI_min) estimation. In this study, the flesh fly Parasarcophaga similis (Meade 1876) was reared at nine constant temperatures ranging from 15°C to 35°C to examine indicators for estimating their age. We generated three development models, including isomorphen diagram, isomegalen diagram, and thermal summation model. Larval body length at different rearing temperatures was fit into an L = a + bT + cT² + dT³ equation with which the relationship between the larval body length (L) and the time after larviposition (T) was confirmed. The pupal stage was categorized into 13 substages according to intrapuparial morphological changes, and a detailed table was generated of the pupal developmental stages at five rearing temperatures, 15°C, 20°C, 25°C, 30°C, and 35°C. This study provides fundamental data in supporting P. similis as an indicator for PMI_min estimation.     

Taphonomic Marks on Pig Tissue Due to Cadaveric Coleoptera Activity Under Controlled Conditions

The aim of this work was to study taphonomic marks that cadaveric coleopteran can produce under controlled conditions. To evaluate this, pig trotters were initially exposed to adults of Dermestes maculatus De Geer at 21 ± 5°C and a 12:12‐h day/night cycle. Observations were made and photographs taken every 4–5 days for 9 months. When feeding and reproducing, D. maculatus produced, in both adult and larvae stages, different types of marks such as holes, striations, scratches, and pits in several kinds of tissue such as integumental, connective, and muscular, in both their fresh and dried stages. Bite marks were also evident. The results in this study provide not only taphonomic but also biological and forensic information. This is the first time that this kind of experiment has been performed.     

Diurnal and Nocturnal Flight Activity of Blow Flies (Diptera: Calliphoridae) in a Rainforest Fragment in Brazil: Implications for the Colonization of Homicide Victims

Nocturnal flight of blow flies (Diptera: Calliphoridae) is a controversial issue in forensic entomology. We performed two field experiments to investigate the diurnal and nocturnal activity of six blow fly species in a rainforest fragment in Brazil. Initially, nocturnal (17:30–05:30) versus diurnal (05:30–17:30) flight activity was investigated. Only 3.9% of adults were collected at night, mostly the native species Mesembrinella bicolor, and nocturnal oviposition did not occur. In the second experiment, collection of adults took place at the following intervals: 05:30–08:30, 08:30–11:30, 11:30–14:30, and 14:30–17:30. The proportions of adults did not differ significantly among the four diurnal intervals, except for Hemilucilia segmentaria, which was captured more frequently in the early morning. Calliphoridae has predominantly diurnal behavior, not laying eggs in darkness. The association of the native species M. bicolor, Hemilucilia semidiaphana, and H. segmentaria to forested areas reinforces the forensic relevance of data on their flight pattern.     

利用COI序列序列鉴定常见嗜尸性蝇种

目的 检测嗜尸性蝇类线粒体DNA(mtDNA)细胞色素氧化酶辅酶Ⅰ(COI)中278bp序列,鉴定蝇科3属5种嗜尸性蝇,解决其形态学种类鉴定的难题,为死亡时间推断提供技术支持.方法 从15省、市(地区)室外草地家兔尸体上采集蝇科3属5种共计18个蝇类成蝇样本,提取mtDNA进行PCR扩增,序列测定且上传GENBANK,...