Research

6118 KiB

Open AccessFeature PaperArticle

Connecting the Dots: From an Easy Method to Computerized Species Determination

by Senta Niederegger, Klaus-Peter Döge, Marcus Peter, Tobias Eickhölter and Gita Mall

Insects 2017, 8(2), 52; https://doi.org/10.3390/insects8020052 - 18 May 2017

Cited by 4 | Viewed by 4369

Differences in growth rate of forensically important dipteran larvae make species determination an essential requisite for an accurate estimation of time since colonization of the body. Interspecific morphological similarities, however, complicate species determination. Muscle attachment site (MAS) patterns on the inside of the [...] Read more.

Differences in growth rate of forensically important dipteran larvae make species determination an essential requisite for an accurate estimation of time since colonization of the body. Interspecific morphological similarities, however, complicate species determination. Muscle attachment site (MAS) patterns on the inside of the cuticula of fly larvae are species specific and grow proportionally with the animal. The patterns can therefore be used for species identification, as well as age estimation in forensically important dipteran larvae. Additionally, in species where determination has proven to be difficult—even when employing genetic methods—this easy and cheap method can be successfully applied. The method was validated for a number of Calliphoridae, as well as Sarcophagidae; for Piophilidae species, however, the method proved to be inapt. The aim of this article is to assess the utility of the MAS method for applications in forensic entomology. Furthermore, the authors are currently engineering automation for pattern acquisition in order to expand the scope of the method. Automation is also required for the fast and reasonable application of MAS for species determination. Using filters on digital microscope pictures and cross-correlating them within their frequency range allows for a calculation of the correlation coefficients. Such pattern recognition permits an automatic comparison of one larva with a database of MAS reference patterns in order to find the correct, or at least the most likely, species. This facilitates species determination in immature stages of forensically important flies and economizes time investment, as rearing to adult flies will no longer be required. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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1208 KiB

Open AccessFeature PaperArticle

Factors Affecting Species Identifications of Blow Fly Pupae Based upon Chemical Profiles and Multivariate Statistics

by William Kranz, Clinton Carroll, Darren A. Dixon, John V. Goodpaster and Christine J. Picard

Insects 2017, 8(2), 43; https://doi.org/10.3390/insects8020043 - 11 Apr 2017

Cited by 6 | Viewed by 4741

Abstract

Alternative methods for the identification of species of blow fly pupae have been developed over the years that consist of the analyses of chemical profiles. However, the effect of biotic and abiotic factors that could influence the predictive manner for the tests have [...] Read more.

Alternative methods for the identification of species of blow fly pupae have been developed over the years that consist of the analyses of chemical profiles. However, the effect of biotic and abiotic factors that could influence the predictive manner for the tests have not been evaluated. The lipids of blowfly pupae (Cochliomyia macellaria, Lucilia cuprina, Lucilia sericata, and Phormia regina) were extracted in pentane, derivatized, and analyzed by total-vaporization solid phase microextraction gas chromatography-mass spectrometry (TV-SPME GC-MS). Peak areas for 26 compounds were analyzed. Here we evaluated one biotic factor (colonization) on four species of blow flies to determine how well a model produced from lipid profiles of colonized flies predicted the species of flies of offspring of wild-caught flies and found very good species identification following 10 generations of inbreeding. When we evaluated four abiotic factors in our fly rearing protocols (temperature, humidity, pupation substrate, and diet), we found that the ability to assign the chemical profile to the correct species was greatly reduced. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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3825 KiB

Open AccessFeature PaperArticle

Post-Colonization Interval Estimates Using Multi-Species Calliphoridae Larval Masses and Spatially Distinct Temperature Data Sets: A Case Study

by Courtney R. Weatherbee, Jennifer L. Pechal, Trevor Stamper and M. Eric Benbow

Insects 2017, 8(2), 40; https://doi.org/10.3390/insects8020040 - 04 Apr 2017

Cited by 16 | Viewed by 6361

Abstract

Common forensic entomology practice has been to collect the largest Diptera larvae from a scene and use published developmental data, with temperature data from the nearest weather station, to estimate larval development time and post-colonization intervals (PCIs). To evaluate the accuracy of PCI [...] Read more.

Common forensic entomology practice has been to collect the largest Diptera larvae from a scene and use published developmental data, with temperature data from the nearest weather station, to estimate larval development time and post-colonization intervals (PCIs). To evaluate the accuracy of PCI estimates among Calliphoridae species and spatially distinct temperature sources, larval communities and ambient air temperature were collected at replicate swine carcasses (N = 6) throughout decomposition. Expected accumulated degree hours (ADH) associated with Cochliomyia macellaria and Phormia regina third instars (presence and length) were calculated using published developmental data sets. Actual ADH ranges were calculated using temperatures recorded from multiple sources at varying distances (0.90 m–7.61 km) from the study carcasses: individual temperature loggers at each carcass, a local weather station, and a regional weather station. Third instars greatly varied in length and abundance. The expected ADH range for each species successfully encompassed the average actual ADH for each temperature source, but overall under-represented the range. For both calliphorid species, weather station data were associated with more accurate PCI estimates than temperature loggers associated with each carcass. These results provide an important step towards improving entomological evidence collection and analysis techniques, and developing forensic error rates. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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5956 KiB

Open AccessFeature PaperArticle

Spectral Signatures of Immature Lucilia sericata (Meigen) (Diptera: Calliphoridae)

by Jodie-A. Warren, T. D. Pulindu Ratnasekera, David A. Campbell and Gail S. Anderson

Insects 2017, 8(2), 34; https://doi.org/10.3390/insects8020034 - 23 Mar 2017

Cited by 5 | Viewed by 4343

Abstract

Hyperspectral remote sensing is an innovative technology with applications in many sciences and is a non-destructive method that may offer more precise aging within development stages. Hyperspectral reflectance measurements from the anterior, midsection, and posterior of Lucilia sericata (Meigen) larvae and pupae were [...] Read more.

Hyperspectral remote sensing is an innovative technology with applications in many sciences and is a non-destructive method that may offer more precise aging within development stages. Hyperspectral reflectance measurements from the anterior, midsection, and posterior of Lucilia sericata (Meigen) larvae and pupae were conducted daily from samples of the developing insects beginning at second instar. Only midsection measurements were conducted on second instar larvae due to their size, to ensure that the measurement was not of reflective surroundings. Once measured, all insects were washed with deionized water, blotted with filter paper, and re-measured. Daily age prediction during the post-feeding stage was not impacted by the unwashed insect measurements and was best predicted based on posterior measurements. The second and third instar larvae, which move about their food source, had different contributing coefficients to the functional regression model for the hyperspectral measurements of the washed compared with unwashed specimens. Although washing did not affect the daily prediction within these stages, it is still encouraged in order to decrease the effect of food source on spectral reflectance. Days within the intra-puparial period were best predicted based on anterior measurements and were not well distinguished from one another in the first few days based on midsection and posterior measurements. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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2765 KiB

Open AccessArticle

Comparison of Faunal Scavenging of Submerged Carrion in Two Seasons at a Depth of 170 m, in the Strait of Georgia, British Columbia

by Gail S. Anderson and Lynne S. Bell

Insects 2017, 8(1), 33; https://doi.org/10.3390/insects8010033 - 13 Mar 2017

Cited by 13 | Viewed by 6008

Abstract

The taphonomy of carcasses submerged in the ocean is little understood, yet it is extremely important ecologically and forensically. The objectives of this study were to determine the fate of pig carcasses as human proxies in the Strait of Georgia at 170 m [...] Read more.

The taphonomy of carcasses submerged in the ocean is little understood, yet it is extremely important ecologically and forensically. The objectives of this study were to determine the fate of pig carcasses as human proxies in the Strait of Georgia at 170 m in spring and fall. Using Ocean Networks Canada’s Victoria Experimental Network Underseas (VENUS) observatory, two carcasses per season were placed under a cabled platform hosting a webcam and instruments measuring water chemistry. Two minutes of video were recorded every 15 min. In spring, Lyssianassidae amphipods and Pandalus platyceros were immediately attracted and fed on the carcasses, the amphipods removed the bulk of the soft tissue from the inside whilst the shrimp shredded the skin and tissue. The carcasses were skeletonized on Days 8 and 10. In fall, Metacarcinus magister was the major scavenger, removing most of the soft tissue from one carcass. Amphipods did not arrive in large numbers until Day 15, when they skeletonized the scavenged carcass by Day 22 and the less scavenged carcass by Day 24. Amphipods remained for some days after skeletonization. This skeletonization was very different from previous experiments at different depths and habitats. Such data are very valuable for predicting preservation, planning recoveries, and managing family expectations. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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Review

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1655 KiB

Open AccessFeature PaperReview

Abiotic and Biotic Factors Regulating Inter-Kingdom Engagement between Insects and Microbe Activity on Vertebrate Remains

by Heather R. Jordan and Jeffery K. Tomberlin

Insects 2017, 8(2), 54; https://doi.org/10.3390/insects8020054 - 24 May 2017

Cited by 33 | Viewed by 44060

Abstract

Abstract: A number of abiotic and biotic factors are known to regulate arthropod attraction, colonization, and utilization of decomposing vertebrate remains. Such information is critical when assessing arthropod evidence associated with said remains in terms of forensic relevance. Interactions are not [...] Read more.

Abstract: A number of abiotic and biotic factors are known to regulate arthropod attraction, colonization, and utilization of decomposing vertebrate remains. Such information is critical when assessing arthropod evidence associated with said remains in terms of forensic relevance. Interactions are not limited to just between the resource and arthropods. There is another biotic factor that has been historically overlooked; however, with the advent of high-throughput sequencing, and other molecular techniques, the curtain has been pulled back to reveal a microscopic world that is playing a major role with regards to carrion decomposition patterns in association with arthropods. The objective of this publication is to review many of these factors and draw attention to their impact on microbial, specifically bacteria, activity associated with these remains as it is our contention that microbes serve as a primary mechanism regulating associated arthropod behavior. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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697 KiB

Open AccessFeature PaperReview

Insect Artifacts Are More than Just Altered Bloodstains

by David Rivers and Theresa Geiman

Insects 2017, 8(2), 37; https://doi.org/10.3390/insects8020037 - 28 Mar 2017

Cited by 23 | Viewed by 8849

Abstract

The bases for forensic entomology are that insects and their arthropod relatives can serve as evidence in criminal, medical and civil legal matters. However, some of the very same species that provide utility to legal investigations can also complicate crime scenes by distorting [...] Read more.

The bases for forensic entomology are that insects and their arthropod relatives can serve as evidence in criminal, medical and civil legal matters. However, some of the very same species that provide utility to legal investigations can also complicate crime scenes by distorting existing body fluid evidence (e.g., bloodstains, semen, saliva) and/or depositing artifacts derived from the insect alimentary canal at primary or secondary crime scenes. The insect contaminants are referred to as insect stains, artifacts, specks or spots, and are most commonly associated with human bloodstains. This review will discuss the different types of insect artifacts that have been described from crime scenes and laboratory experiments, as well as examine insect contaminates (non-blood based artifacts, transfer patterns, meconium, and larval fluids) that have received little research or case attention. Methods currently used for distinguishing insect stains from human body fluids will also be discussed and compared to presumptive tests used for identification of human body fluids. Since all available methods have severe limitations, areas of new research will be identified for the purpose of development of diagnostic techniques for detection of insect artifacts. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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Other

Jump to: Research, Review

713 KiB

Open AccessFeature PaperPerspective

The Role of a PMI-Prediction Model in Evaluating Forensic Entomology Experimental Design, the Importance of Covariates, and the Utility of Response Variables for Estimating Time Since Death

by Jeffrey Wells and Lynn LaMotte

Insects 2017, 8(2), 47; https://doi.org/10.3390/insects8020047 - 01 May 2017

Cited by 15 | Viewed by 7348

Abstract

The most common forensic entomological application is the estimation of some portion of the time since death, or postmortem interval (PMI). To our knowledge, a PMI estimate is almost never accompanied by an associated probability. Statistical methods are now available for calculating confidence [...] Read more.

The most common forensic entomological application is the estimation of some portion of the time since death, or postmortem interval (PMI). To our knowledge, a PMI estimate is almost never accompanied by an associated probability. Statistical methods are now available for calculating confidence limits for an insect-based prediction of PMI for both succession and development data. In addition to it now being possible to employ these approaches in validation experiments and casework, it is also now possible to use the criterion of prediction performance to guide training experiments, i.e., to modify carrion insect development or succession experiment design in ways likely to improve the performance of PMI predictions using the resulting data. In this paper, we provide examples, derived from our research program on calculating PMI estimate probabilities, of how training data experiment design can influence the performance of a statistical model for PMI prediction. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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176 KiB

Open AccessTechnical Note

Comparing Species Composition of Passive Trapping of Adult Flies with Larval Collections from the Body during Scene-Based Medicolegal Death Investigations

by Michelle R. Sanford

Insects 2017, 8(2), 36; https://doi.org/10.3390/insects8020036 - 24 Mar 2017

Cited by 12 | Viewed by 3564

Abstract

Collection of insects at the scene is one of the most important aspects of forensic entomology and proper collection is one of the biggest challenges for any investigator. Adult flies are highly mobile and ubiquitous at scenes, yet their link to the body [...] Read more.

Collection of insects at the scene is one of the most important aspects of forensic entomology and proper collection is one of the biggest challenges for any investigator. Adult flies are highly mobile and ubiquitous at scenes, yet their link to the body and the time of colonization (TOC) and post-mortem interval (PMI) estimates is not well established. Collection of adults is widely recommended for casework but has yet to be rigorously evaluated during medicolegal death investigations for its value to the investigation. In this study, sticky card traps and immature collections were compared for 22 cases investigated by the Harris County Institute of Forensic Sciences, Houston, TX, USA. Cases included all manner of death classifications and a range of decomposition stages from indoor and outdoor scenes. Overall, the two methods successfully collected at least one species in common only 65% of the time, with at least one species unique to one of the methods 95% of the time. These results suggest that rearing of immature specimens collected from the body should be emphasized during training to ensure specimens directly associated with the colonization of the body can be identified using adult stages if necessary. Full article

(This article belongs to the Special Issue Advances in Forensic Entomology)

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