Publications by authors named "Villet M"

Article Synopsis
  • * The study details the morphology of the Canarian copper fly (Calliphora splendens) and compares it to other Calliphora species found in Africa, the Iberian Peninsula, and Macaronesia.
  • * Genetic analysis shows a close connection between C. splendens and several other Calliphora species, while its ability to produce unisexual offspring and its association with the endemic laurel forest habitat highlight its relict nature.
View Article and Find Full Text PDF

Forensic entomologists use the maturity of necrophagous larvae to estimate the minimum post-mortem interval (PMI), ideally taking account of effects that xenobiotics in the corpse may have on insect maturation. Forensic toxicologists may employ larvae to detect drugs in drug-related deaths when human samples are unavailable. Yet current pre-analytical practices of these two professions differ significantly, impeding the successful use of the same samples.

View Article and Find Full Text PDF

The rat dorsomedial (DMS) and dorsolateral striatum (DLS), equivalent to caudate nucleus and putamen in primates, are required for goal-directed and habit behaviour, respectively. However, it is still unclear whether and how this functional dichotomy emerges in the course of learning. In this study, we investigated this issue by recording DMS and DLS single neuron activity in rats performing a continuous spatial alternation task, from the acquisition to optimized performance.

View Article and Find Full Text PDF

Nutrient composition in obesogenic diets may influence the severity of disorders associated with obesity such as insulin-resistance and chronic inflammation. Here we hypothesized that obesogenic diets rich in fat and varying in fatty acid composition, particularly in omega 6 (ω6) to omega 3 (ω3) ratio, have various effects on energy metabolism, neuroinflammation and behavior. Mice were fed either a control diet or a high fat diet (HFD) containing either low (LO), medium (ME) or high (HI) ω6/ω3 ratio.

View Article and Find Full Text PDF

Blowfly larvae are the insects primarily responsible for the active stage of decomposition of exposed vertebrate remains and are the most frequently collected entomological evidence during forensic investigations of death. The necrophagous calliphorids in continental Africa that consistently develop on large vertebrate carrion include 11 species belonging to four genera: Calliphora, Chrysomya, Hemipyrellia and Lucilia. Most of these species are widespread in Africa and frequently reported on large animal carcasses and carrion and human corpses.

View Article and Find Full Text PDF

Background: Rhiniinae (Diptera, Calliphoridae) is a taxon of nearly 400 known species, many of them termitophilous. Approximatelly 160 valid species in 16 genera are Afrotropical, with over 60 of them occurring in South Africa. The taxonomy of this group is outdated, as most studies of the South African taxa were conducted 40 to 70 years ago (mostly by Salvador Peris and Fritz Zumpt).

View Article and Find Full Text PDF

Contamination of a genetic sample with DNA from one or more nontarget species is a continuing concern of molecular phylogenetic studies, both Sanger sequencing studies and next-generation sequencing studies. We developed an automated pipeline for identifying and excluding likely cross-contaminated loci based on the detection of bimodal distributions of patristic distances across gene trees. When contamination occurs between samples within a data set, a comparison between a contaminated sample and its contaminant taxon will yield bimodal distributions with one peak close to zero patristic distance.

View Article and Find Full Text PDF

Background: Many flies have specially evolved feeding mechanisms to imbibe liquids of specific viscosities. Observations of feeding on atypical liquids are notable because of their rarity.

New Information: We report the first record of intrusive fluid feeding on vertebrate carrion by .

View Article and Find Full Text PDF

Reactive blending of immiscible polymers is an important process for synthesizing polymer blends with superior properties. We use a phase-field model to understand reaction dynamics and morphology evolution by diffusive transport in layered films of incompatible, end-reactive polymers. We thoroughly investigate this phenomenon over a large parameter space of interface shapes, layer thicknesses, reaction rates specified by a Damkohler number (Da), and Flory-Huggins interaction parameter (), under static conditions with no external fields.

View Article and Find Full Text PDF

A facile way to generate compatibilized blends of immiscible polymers is through reactive blending of end-functionalized homopolymers. The reaction may be reversible or irreversible depending on the end-groups and is affected by the immiscibility and transport of the reactant homopolymers and the compatibilizing copolymer product. Here we describe a phase-field framework to model the combined dynamics of reaction kinetics, diffusion, and multi-component thermodynamics on the evolution of the microstructure and reaction rate in reactive blending.

View Article and Find Full Text PDF

The taxonomy of the genus Enterobacter can be confusing and has been considerably revised in recent years. We propose a PCR and amplicon sequencing technique based on a partial sequence of the gene for species assignment consistent with DNA-DNA digital hybridization (dDDH) and pairwise average nucleotide identity (ANI). We performed a validation of the method by comparing the type strains of each species, sequences obtained from the GenBank database, and clinical specimens.

View Article and Find Full Text PDF

Accurate age estimates of immature necrophagous insects associated with a human or animal body can provide evidence of how long the body has been dead. These estimates are based on species-specific details of the insects' aging processes, and therefore require accurate species identification and developmental stage estimation. Many professionals who produce or use identified organisms as forensic evidence have little training in taxonomy or metrology, and appreciate the availability of formalized principles and standards for biological identification.

View Article and Find Full Text PDF

The taxonomy and diversity of Zumpt, 1958, an exclusive Afrotropical genus, had not been reviewed recently. The genus included six nominal species, but the status of several of them was debated. Identification of most species depends on characters of the male terminalia; females are poorly known and, in several cases, are not adequately diagnosed.

View Article and Find Full Text PDF

This study investigates genetic diversity in three species of Ephemeroptera, one eurytopic and therefore widespread () and two stenotopic and thus endemic ( and ) species, all of which co-occur in the southern Great Escarpment, South Africa. Mitochondrial DNA was analysed to compare the genetic diversity between the habitat generalist and the two habitat specialists. showed no indication of population genetic structure due to geographic location, while both species revealed clear genetic differentiation between geographic localities and catchments, evident from phylogenetic analyses and high F values from AMOVA.

View Article and Find Full Text PDF

Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857.

View Article and Find Full Text PDF

Most studies of decomposition in forensic entomology and taphonomy have used non-human cadavers. Following the recommendation of using domestic pig cadavers as analogues for humans in forensic entomology in the 1980s, pigs became the most frequently used model cadavers in forensic sciences. They have shaped our understanding of how large vertebrate cadavers decompose in, for example, various environments, seasons and after various ante- or postmortem cadaver modifications.

View Article and Find Full Text PDF

African horse sickness (AHS), a disease of equids caused by the AHS virus, is of major concern in South Africa. With mortality reaching up to 95% in susceptible horses and the apparent reoccurrence of cases in regions deemed non-endemic, most particularly the Eastern Cape, epidemiological research into factors contributing to the increase in the range of this economically important virus became imperative. The vectors, Culicoides (Diptera: Ceratopogonidae), are considered unable to proliferate during the unfavourable climatic conditions experienced in winter in the province, although the annual occurrence of AHS suggests that the virus has become established and that vector activity continues throughout the year.

View Article and Find Full Text PDF

An upsurge in African horse sickness (AHS) in the Eastern Cape, South Africa, from 2006 led to an epidemiological reassessment of the disease there. Light trapping surveys carried out near horses, donkeys and zebras in 2014-2016 collected 39 species of Culicoides midge (Diptera: Ceratopogonidae) that are potential vectors of AHS. To establish if these midges fed on equids, DNA sequences were obtained from the gut contents of 52 female midges (35 freshly blood-fed, 13 gravid and four parous), representing 11 species collected across 11 sites.

View Article and Find Full Text PDF

The seasonal activity of adults of eight forensically important blow fly species [Calliphora croceipalpis (Diptera: Calliphoridae), Jaennicke, Lucilia sericata (Meigen) (Diptera: Calliphoridae), L. cuprina (Wiedemann) (Diptera: Calliphoridae), Chrysomya chloropyga (Wiedemann) (Diptera: Calliphoridae), Ch. albiceps (Wiedemann) (Diptera: Calliphoridae), Ch.

View Article and Find Full Text PDF

(Fabricius, 1794) occurs on every continent and is closely associated with carrion and decaying material in human environments. Its abilities to find dead bodies and carry pathogens give it a prominence in human affairs that may involve prosecution or litigation, and therefore forensic entomologists. The identification, geographical distribution and biology of the species are reviewed to provide a background for approaches that four branches of forensic entomology (urban, stored-product, medico-criminal and environmental) might take to investigations involving this fly.

View Article and Find Full Text PDF

A molecular phylogeny and a review of family-group classification are presented for 137 species (ca. 125 genera) of the insect family Cicadidae, the true cicadas, plus two species of hairy cicadas (Tettigarctidae) and two outgroup species from Cercopidae. Five genes, two of them mitochondrial, comprise the 4992 base-pair molecular dataset.

View Article and Find Full Text PDF

The genus Chondrocyclus Ancey, 1898 contains the majority of southern African members of the Cyclophoridae, a large family of operculate land snails. We present the first molecular phylogeny of the genus based on two mitochondrial genes (16S and CO1) and complement this with an appraisal of morphological characters relating to the shell and soft parts. Worn shells on which some descriptions and records of different species were based appear to be indistinguishable morphologically, creating taxonomic confusion.

View Article and Find Full Text PDF

Necrophagous blowflies can provide an excellent source of evidence for forensic entomologists and are also relevant to problems in public health, medicine, and animal health. However, access to useful information about these blowflies is constrained by the need to correctly identify the flies, and the poor availability of reliable, accessible identification tools is a serious obstacle to the development of forensic entomology in the majority of African countries. In response to this need, a high-quality key to the adults of all species of forensically relevant blowflies of Africa has been prepared, drawing on high-quality entomological materials and modern focus-stacking photomicroscopy.

View Article and Find Full Text PDF