Observations on morphology of immature Lucilia porphyrina (Diptera: Calliphoridae), a fly species of forensic importance

Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae): A potentially forgotten forensically important species in Malaysia

Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) has been collected in human forensic case work. This species is endemic in Malaysia but is not one of the most common species and is often found in outdoor cases. However, it is hypothesized that the presence of L. cuprina larvae may provide useful information in forensic case studies in Malaysia where this species has previously been ignored. This review will discuss the current background knowledge on L. cuprina, particularly when it comes to other forensic cases in Malaysia. General biology as well as key information for forensic work such as geographical distribution and developmental data will be reviewed. Finally, we discuss the potential for L. cuprina to provide beneficial and unique forensic insight into indoor cases with refuse.

Mitogenome-wise codon usage pattern from comparative analysis of the first mitogenome of Blepharipa sp. (Muga uzifly) with other Oestroid flies

Uziflies (Family: Tachinidae) are dipteran endoparasites of sericigenous insects which cause major economic loss in the silk industry globally. Here, we are presenting the first full mitogenome of Blepharipa sp. (Acc: KY644698, 15,080 bp, A + T = 78.41%), a dipteran parasitoid of Muga silkworm (Antheraea assamensis) found in the Indian states of Assam and Meghalaya. This study has confirmed that Blepharipa sp. mitogenome gene content and arrangement is similar to other Tachinidae and Sarcophagidae flies of Oestroidea superfamily, typical of ancestral Diptera. Although, Calliphoridae and Oestridae flies have undergone tRNA translocation and insertion, forming unique intergenic spacers (IGS) and overlapping regions (OL) and a few of them (IGS, OL) have been conserved across Oestroidea flies. The Tachinidae mitogenomes exhibit more AT content and AT biased codons in their protein-coding genes (PCGs) than the Oestroidea counterpart. About 92.07% of all (3722) codons in PCGs of this new species have A/T in their 3rd codon position. The high proportion of AT and repeats in the control region (CR) affects sequence coverage, resulting in a short CR (Blepharipa sp.: 168 bp) and a smaller tachinid mitogenome. Our research unveils those genes with a high AT content had a reduced effective number of codons, leading to high codon usage bias. The neutrality test shows that natural selection has a stronger influence on codon usage bias than directed mutational pressure. This study also reveals that longer PCGs (e.g., nad5, cox1) have a higher codon usage bias than shorter PCGs (e.g., atp8, nad4l). The divergence rates increase nonlinearly as AT content at the 3rd codon position increases and higher rate of synonymous divergence than nonsynonymous divergence causes strong purifying selection. The phylogenetic analysis explains that Blepharipa sp. is well suited in the family of insectivorous tachinid maggots. It's possible that biased codon usage in the Tachinidae family reduces the effective number of codons, and purifying selection retains the core functions in their mitogenome, which could help with efficient metabolism in their endo-parasitic life style and survival strategy.

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.

Morphology of immature blow fly Hypopygiopsis infumata (Bigot) (Diptera: Calliphoridae), a potential species of forensic importance

Blow flies of the genus Hypopygiopsis are forensically-important, as their larvae are commonly associated with human corpses. Within a forensic entomology context, species identification of specimens collected from human corpses is the initial mandatory step in the investigation. Without identification, complete interpretation of entomological evidence is challenged. In this study, the ultrastructures of eggs, all instars, and puparia of Hypopygiopsis infumata (Bigot) are presented based on assessment with scanning electron microscopy (SEM) and light microscopy (LM). Distinctive features used for species identification of all stages are highlighted. Eggs have a slightly widening median area extending almost the entire length. Larvae are vermiform-shaped, creamy white, and have a smooth integument. The pseudocephalon of larvae bears sensory structures (i.e., antennal dome, maxillary palpus and ventral organ). In the first instar, two tufts of cirri are observed along the dorsal margin of the mouth opening. In the second and third instars, six minute tubercles are present along the peripheral rims of the last abdominal segment. The anterior spiracle of the second, third instar, and puparia is fan-shape of single row, comprising 9-11 papillae. The cuticular spines between the 1^st and 2^nd thoracic segments of the third instar possess many rows of posteriorly-projecting acuminate spines in clusters. In puparia, at the latero-dorsal edge of the 1^st abdominal segment, a cluster of ∼92 bubble membranes is present in young puparia (20-24 h). The peristigmatic tufts adjacent to the posterior spiracle of the second instar, third instar, and puparia are heavily branches of long, fine hairs. Our results demonstrate the morphology of eggs, larvae, and puparia of H. infumata are similar to other species in Hypopygiopsis. This study highlighted the main features of cephaloskeleton of H. infumata larvae as observed under LM. Particular attention is given to oral sclerite and rough surface of dorsal cornua which can distinguish between H. infumata and H. tumrasvini.

Morphology of immature stages of blow fly, Lucilia sinensis Aubertin (Diptera: Calliphoridae), a potential species of forensic importance

Lucilia sinensis Aubertin (Diptera: Calliphoridae) is a blow fly species of potential forensic importance since adults are attracted to, and colonize, decomposing vertebrate remains. Blow fly larvae associated with human corpses can be useful evidence in forensic investigations; however, their use is dependent in most cases on proper species identification and availability of developmental data. For identification, morphological information on each life stage is traditionally used. We used scanning electron microscopy (SEM) to examine the ultrastructure of eggs, all instars, and puparia, of L. sinensis. The important characteristics used to differentiate L. sinensis from other species are provided. Distinctive features of the eggs are the slight widening median area extending almost the entire length. The last abdominal segment of the first instar bears elongated outer ventral tubercles along the rim of the last abdominal segment. These tubercles, as well as the well developed median and outer dorsal tubercles, are more prominent in the second and third instars. The surface integument of the tubercles is equipped with circular rows of microtrichia. Pairs of inner dorsal tubercle are absent. Each anterior spiracle is comprised of 9-12 papillae arrange in a single row in the second and third instars. As for the third instar, the dorsal spines between the first and second thoracic segments are delicate, narrow, small, and close together (as row or set). The peristigmatic tufts adjacent to the posterior spiracle of the third instar are moderately branches of short, fine hairs, but minute in puparia. In conclusion, the prominent outer ventral tubercle in all instars and puparia is a new diagnostic feature of L. sinensis and helpful in differentiating it from other Lucilia species that are forensically important. The description of immature L. sinensis in this study will be useful for forensic entomologists in countries where this species exists.

Malaria vector Anopheles culicifacies sibling species differentiation using egg morphometry and morphology

Background

The malaria vector Anopheles culicifacies (sensu lato) is an important malaria vector in Southeast Asia which comprises of five sibling species namely A, B, C, D and E. However, only a few forms have been identified as malaria vectors in various endemic countries. Currently, for the first time egg morphometry and morphology has been used to differentiate the three known vector sibling species of Anopheles culicifacies collected from malaria endemic Madhya Pradesh state of central India.

Methods

The adult An. culicifacies (s.l.) was collected from five districts using standard mosquito collection methods. Adult female mosquitoes were allowed to lay eggs individually. The emerged mosquitoes were identified using allele specific polymerase chain reaction (AS-PCR) to sibling species. Eggs of sibling species A, D and E were studied using scanning electron microscopy (SEM) for morphometric and morphological characteristics.

Results

Currently AS-PCR identified four known sibling species (B, C, D and E) of An. culicifacies in the study area. The surface morphology and morphometric attributes of the sibling species A, D and E eggs considerably differed from each other. An. culicifacies E had a narrow deck as compared to A and D, while An. culicifacies A had a bigger micropyle with 6–7 sectors as compared to D and E that had 6 sectors. An. culicifacies D had the smallest float (the structure present on sides of the egg surface in which air is filled that help in floating) and the number of ribs was also fewer than for An. culicifacies A and E.

Conclusions

The present study provides the first evidence that in addition to PCR assay, sibling species of An. culicifacies can also be differentiated using morphological and morphometric characteristics of the egg stage. The results also advocate that the sibling species of An. culicifacies are morphologically dissimilar and can be resolved using advanced microscopy.

Application of DNA barcoding for identifying forensically relevant Diptera from northern Thailand

In recent decades, forensic entomology has become a useful tool in criminal investigations all over the world. Species-specific identification of flies plays an important role in this field and is obligatory for accurate calculation of the post-mortem interval. However, not all important colonizers of a corpse can be identified by common morphological keys. Due to similar morphology and the lack of keys for some taxa, especially for immature stages, DNA barcoding has become more popular during the last recent years. This development is particularly important for countries like Thailand, in which forensic entomology is a newly developing research area and which faces several challenges such as a high biodiversity of fly species. The most commonly used barcoding region in forensic entomology, the mitochondrial cytochrome oxidase subunit 1 (coI) gene, as well as a 1000-bp-long region of the 28S nuclear rRNA gene, was used to analyze and establish the molecular barcodes of 13 different species of flies of forensic relevance in northern Thailand.

Sarcophaga (Liosarcophaga) tibialis Macquart 1851 (Diptera: Sarcophagidae): micromorphology of preimaginal stages of a fly of medical and veterinary interest

Sarcophagids are a large family of Diptera, with a worldwide distribution. They are related to decomposing organic matter and are very interesting for health science and in forensic cases since many species produce myiasis and occur in human corpses. This family is considered difficult to study, particularly with regard to their immature stages, to which little attention has been paid. Genus Sarcophaga Meigen, 1826 is composed of species of very similar morphology, making very difficult to distinguish. Knowledge of the immature stages of this genus is important because such stages occupy the greater part of the life cycle, so that establishing a basis for their identification will increase their usefulness in systematic and applied sciences. This contribution presents a detailed study of the morphological features, both external and internal, of the preimaginal stages of Sarcophaga (Liosarcophaga) tibialis Macquart, 1851, providing a taxonomical context for the correct identification of Liosarcophaga species of forensic interest in the Iberian Peninsula. Both light and scanning electron microscopy were applied. Complete descriptions of every stage are provided and illustrated, and their usefulness for species comparison, taking into account our uneven knowledge of morphologically immature stages of this subgenus, is indicated. Features of the cephalopharyngeal skeleton, such as the shape of the mouth hook and the intermediate and basal sclerites, and external morphology, such as the pattern of spinose band and anterior and posterior spiracles, proved useful for separating species. Finally, tentative identification keys based on light microscopy observation to distinguish S. (L.) tibialis from other species of forensic interest belonging to Liosarcophaga subgenus are proposed for every immature stage.

Species identification of Middle Eastern blowflies (Diptera: Calliphoridae) of forensic importance

The lack of reliable tools for species identification of necrophagous blowflies of the Middle East is a serious obstacle to the development of forensic entomology in the majority of countries of this region. Adding to the complexity of diagnosing the regional fauna is that species representing three different zoogeographical elements exist in sympatry. In response to this situation, a high-quality key to the adults of all species of forensically relevant blowflies of the Middle East has been prepared. Thanks to the modern technique of image-stack stereomicroscopy and high-quality entomological materials, this new key can be easily applied by investigators inexperienced in the taxonomy of blowflies. The major technical problems relating to the species identification of necrophagous blowflies of the Middle East are also discussed.

Rapid discrimination of maggots utilising ATR-FTIR spectroscopy

Entomological evidence is used in forensic investigations to indicate time since death. The species and age of maggots or flies that are present at the scene can be used when estimating how much time has passed since death. Current methods that are used to identify species and developmental stage of larvae and fly samples are highly subjective, costly and often time consuming processes and require the expertise of an entomologist or species identification via DNA analysis. The use of vibrational spectroscopy, as an alternative identification method, would allow for a quicker, cheaper and less subjective technique and would allow entomological evidence to be used more commonly in the forensic process. This proof of principle study shows the potential for using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) as a rapid tool for differentiating between various species of larvae, such as those commonly found at crime scenes. The proposed regime would provide a rapid and valuable tool resulting in reduced time for both species identification and life cycle determination, particularly in forensic situations.

Micromorphology of immature stages of Sarcophaga (Liopygia) cultellata Pandellé, 1896 (Diptera: Sarcophagidae), a forensically important fly

The Sarcophagidae are one of the most numerous groups of Diptera in the world, consisting of many species of forensic interest, whose immature stages are useful in the estimation of postmortem interval. The immature stages of some species of forensic importance still remain unknown or undescribed, like in the case of Sarcophaga (Liopygia) cultellata Pandellé, 1986, a species restricted to the Iberian Peninsula, south of France and north of Italy, which shares a ecological niche with species of the same subgenus, e.g., Sarcophaga (Liopygia) argyrostoma (Robineau-Desvoidy, 1830) and Sarcophaga (Liopygia) crassipalpis Macquart, 1839, making it necessary to lay the groundwork for a proper specific differentiation before it can be successfully applied in forensic practice. This study provides the first micromorphological description of all preimaginal stages of S. (L.) cultellata using light microscopy and scanning electron microscopy (SEM), the results of which allow the morphology of the main features to be followed during the immature life cycle. We propose a combination of features for distinguishing Liopygia from other sarcophagid subgenera, based on the current level of morphological knowledge of immature stages. S. (L.) cultellata can be differentiated from S. (L.) argyrostoma and S. (L.) crassipalpis in every immature stage by both light microscopy and SEM. The presence of tegumental warts and a fan-shaped anterior spiracle with a single row of 15-18 respiratory papillae allow distinguishing the third instar larvae of S. (L.) cultellata from other Sarcophaga species described hitherto by SEM. Identification keys based on light microscopy observations are provided, covering all the immature stages of Liopygia subgenus occurring in the Iberian Peninsula.

Adhesive attachments of the endangered botfly, Portschinskia magnifica (Diptera: Oestridae)

Portschinskia magnifica (Diptera: Oestridae) is an endangered subcutaneous parasitic fly that is mainly distributed in Eurasia. The external morphology of the main adhesive attachments that include the pretarsus and tarsus is studied using scanning electron microscopy. Two types of tenent setae that are characterised as spoon-like tip and pointed-like tip, which can increase the contact points for attachment to a surface, are described in this study. Hairs around the bristle of the empodium in P. magnifica are much denser than those of other flies, and thus, we proposed that the dense hairs around the empodium may be a more efficient way to perform the sensory function. Compared with saprophagous flies that are reported previously, the microsculpture of the unguitractor plate is obviously different in that microplates are scale-like and similar to those of the water bug, Ranatra linearis. In addition, microtrichia found in the lateral region of the unguitractor plate provides stronger fixation between two surfaces. These results provide anatomical information that allows us to understand the role of the pretarsus as an attachment device.

Morphology of the first instar larva of obligatory traumatic myiasis agents (Diptera: Calliphoridae, Sarcophagidae)

There are only three fly species that are obligate agents of traumatic myiasis of humans and livestock: a single species of flesh fly, Wohlfahrtia magnifica (Sarcophagidae), and two species of blow flies, Chrysomya bezziana and Cochliomyia hominivorax (Calliphoridae). The morphology of their first instar larvae is thoroughly and consistently documented here with light microscopy photographs and scanning electron microscopy micrographs. The following morphological structures are documented: pseudocephalon, antennal complex, maxillary palpus, oral ridges, thoracic and abdominal spinulation, spiracular field, posterior spiracles and cephaloskeleton. New diagnostic features drawn from the cephaloskeleton and the spinulation of abdominal segments, including the anal pad, are discovered and extensively described. Earlier descriptions in the literature are revisited, and major discrepancies between these and the results of the current study are discussed. The present results allow clarification, correction and, especially, complementation of information provided by earlier authors. The relatively distant taxonomic position of all three species is evidence that obligatory myiasis has arisen independently, and the extensively similar morphology in the first instar larvae of Chrysomya bezziana, Cochliomyia hominivorax and W. magnifica in comparison to necrophagous species, especially the enhancement of the anterior part of the cephaloskeleton and the segmental spinulation, is therefore best interpreted as homoplasic adaptations to a life strategy as obligate vertebrate parasites. An identification key for first instar larvae of all obligatory traumatic myiasis agents of mammals is provided.

Ultrastructure of preimaginal stages of Piophila megastigmata McAlpine, 1978 (Diptera, Piophilidae): a fly of forensic importance

Piophila Fallén, 1810 is a genus of small flies composed of two species: Piophila casei (P. casei ) (Linnaeus, 1758), worldwide distributed, and Piophila megastigmata (P. megastigmata ) McAlpine, 1978, recently referred in the Palaearctic Region, from the Iberian Peninsula. Both species share ecological niche and are very interesting for forensic purposes, since they are present in carrion in advance stages of decay and have been found to be related to human corpses. The immature stages of P. megastigmata have ever been described, so this paper gives the ultrastructural morphologies of all preimaginal stages of P. megastigmata studied by light microscopy and scanning electron microscopy (SEM). Particular attention is given to pseudocephalon features—antenna, maxillary palps, facial mask, etc.—cephalopharyngeal skeleton, anterior and posterior spiracles, tegumentary sculpturing, and anal division among others. A comparative analysis of the main distinguishing features is made in order to understand how those features evolve along the developmental process, while larvae II and III are morphologically similar to each other, the larva I shows particular features. Larvae of all stages and pupae are easily distinguishable from other Diptera of forensic importance just based on the presence of trichoid sensilla associated to respiratory slits, instead of peristigmatig tufts, as well as on thewell-known disposition of anal papillae. The shapes of both dorsal edge at the basal part of mouthhook and dorsal bridge of cephalopharyngeal skeleton, and the tegumental ornamentationmay be considered as good features to distinguish the Piophila species, especially for P. megastigmata and P. casei . At the SEM level, shape, number, and arrangement of oral combs, oral ridges, sensilla of maxillary palpus, papillae of anterior spiracle, scales of spiracular field, and posterior spiracles represent good features to distinguish P. megastigmata from P. casei, but further studies will be necessary in West-Paleartic specimens of latter species. The key for identifying third instar larvae of forensically important Piophilidae in the Iberian Peninsula has been updated to include P. megastigmata.

Marked for life: muscle attachment site patterns in blowfly larvae are constant throughout development

The muscular attachment sites (MAS) of blowfly larvae can be visualised as "dots" by removing and staining the cuticle. Each segment bears several rows of MAS. The silhouettes of a subset of those rows in the second, third, and fourth segments were previously shown to be specific for four species of L3 blowfly larvae. In this investigation, the MAS patterns are described for a fifth species (Protophormia terraenovae) and throughout larval development of Calliphora vicina and Calliphora vomitoria. The patterns of P. terraenovae show considerable differences to those of the Calliphora species (larger MAS, characteristic "M" shape in row 4A), thus providing further evidence for the viability of the method as tool for species determination. Larvae with a body length of only 3 mm already show a complete set of MAS expressing identical pattern characteristics as L3 larvae with maximal body length. These characteristics are largely unchanged throughout development. Plotting the row length as a function of the body length throughout development reveals a linear correlation. Therefore, in case of requirement (e.g. fragmentation), not only the species but also the approximate larval age can be calculated with this method.