Dataset Information

First record of Culicoides oxystoma Kieffer and diversity of species within the Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) biting midges in Senegal.

ABSTRACT: The Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) is distributed throughout Africa to northern Asia and Australasia and includes several potential vector species of livestock pathogens. The taxonomy of the species belonging to this species group is confounded by the wide geographical distribution and morphological variation exhibited by many species. In this work, morphological and molecular approaches were combined to assess the taxonomic validity of the species and morphological variants of the Schultzei group found in Senegal by comparing their genetic diversity with that of specimens from other geographical regions. The species list for Senegal was updated with four species: Culicoides kingi, C. oxystoma, C. enderleini and C. nevilli being recorded. This is the first record of C. oxystoma from Africa south of Sahara, and its genetic relationship with samples from Israel, Japan and Australia is presented. This work provides a basis for ecological studies of the seasonal and spatial dynamics of species of this species group that will contribute to better understanding of the epidemiology of the viruses they transmit.

SUBMITTER: Bakhoum MT

PROVIDER: S-EPMC3875552 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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First record of Culicoides oxystoma Kieffer and diversity of species within the Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) biting midges in Senegal.

Bakhoum Mame T MT Fall Moussa M Fall Assane G AG Bellis Glenn A GA Gottlieb Yuval Y Labuschagne Karien K Venter Gert J GJ Diop Mariame M Mall Iba I Seck Momar T MT Allène Xavier X Diarra Maryam M Gardès Laëtitia L Bouyer Jérémy J Delécolle Jean-Claude JC Balenghien Thomas T Garros Claire C

PloS one 20131230 12

The Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) is distributed throughout Africa to northern Asia and Australasia and includes several potential vector species of livestock pathogens. The taxonomy of the species belonging to this species group is confounded by the wide geographical distribution and morphological variation exhibited by many species. In this work, morphological and molecular approaches were combined to assess the taxonomic validity of the species and morphol ...[more]

PMID: 24386366

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Project description:BackgroundCulicoides imicola Kieffer and Culicoides bolitinos Meiswinkel (Diptera: Ceratopogonidae) are both of veterinary importance, being vectors of Schmallenberg, bluetongue and African horse sickness (AHS) viruses. Within South Africa, these Culicoides species show a marked difference in their abundances according to altitude, with C. imicola highly abundant in lower altitudes, but being replaced as the dominant species by C. bolitinos in cooler, high-altitude regions.MethodsThe thermal physiology of field collected adults of each species was determined to evaluate whether it could account for differences in their distribution and abundance. Critical thermal maxima (CTmax) and minima (CTmin), as well as upper and lower lethal temperatures (ULT and LLT) were assessed after acclimation temperatures of 19'C, 24'C and 29'C. Critical thermal limits were determined using an ecologically relevant rate of temperature change of 0.06'C x min(-1).ResultsSignificant differences in CTmin and CTmax were found between acclimation temperatures for C. imicola and C. bolitinos. In C. bolitinos, the LLT of individuals acclimated at 24'C was significantly improved (LLT50 = -6.01'C) compared with those acclimated at the other temperatures (LLT50 = -4'C). Acclimation had a weak (difference in LLT50 of only 1'C) but significant effect on the LLT of C. imicola. When CTmin, CTmax, LLT and ULT were superimposed on daily maximum and minimum temperature records from locations where each tested Culicoides species is dominant, it was found that temperatures frequently declined below the CTmin and LLT of C. imicola at the location where C. bolitinos was dominant.ConclusionsThe distribution and abundance of C. imicola is likely directly constrained by their relatively poor tolerance of lower temperatures. Results for C. bolitinos suggest that the adult phase is hardy, and it is hypothesised that the thermal biology of other life stages could determine their range.

Project description:BackgroundInvestigations of Culicoides fauna, including inventories, were carried out in Morocco at different periods after the country had faced major bluetongue and African horse sickness outbreaks. However, no comprehensive reference publication has provided a clear overview of the Culicoides species diversity. This study reviewed available data on Culicoides biting midge species in Morocco from 1968 to 2015 (published and grey literature in French and English) in order to revise the current checklist, in light of state of the art taxonomic and systematic knowledge, and confirmed the checklist with morphological and molecular identifications of specimens collected from the region of Rabat.MethodsLiterature related to Culicoides collections in Morocco was collated. Authors were contacted to obtain raw data and additional information for the collections. Fresh Culicoides material was collected and examined from two sites around Rabat, the capital of Morocco. Each collected individual was examined and morphologically identified, if possible, to the species level. In addition, molecular identification was performed to separate closely related species, to confirm difficult morphological identifications and to confirm new species records.ResultsA total of 6121 individuals of Culicoides spp. were collected and analyzed and at least 17 species were identified: C. cataneii/C. gejgelensis, C. circumscriptus, C. fagineus, C. festivipennis, C. imicola, C. jumineri, C. kingi, C. longipennis, C. montanus, C. newsteadi, C. obsoletus, C. paolae, C. parotti, C. puncticollis, C. sahariensis, C. scoticus and C. subfagineus. Seven species were confirmed using phylogenetic analyses. Two new species records for Morocco are reported: C. paolae and C. subfagineus.ConclusionsThe Moroccan fauna of Culicoides now includes 54 valid species. Further work would certainly increase this total, as one of the clades we identified was not affiliated to any described and valid species.

Project description:BackgroundHost preference studies in haematophagous insects e.g. Culicoides biting midges are pivotal to assess transmission routes of vector-borne diseases and critical for the development of veterinary contingency plans to identify which species should be included due to their risk potential. Species of Culicoides have been found in almost all parts of the world and known to live in a variety of habitats. Several parasites and viruses are transmitted by Culicoides biting midges including Bluetongue virus and Schmallenberg virus. The aim of the present study was to determine the identity and diversity of blood meals taken from vertebrate hosts in wild-caught Culicoides biting midges near livestock farms.MethodsBiting midges were collected at weekly intervals for 20 weeks from May to October 2009 using light traps at four collection sites on the island Sealand, Denmark. Blood-fed female biting midges were sorted and head and wings were removed for morphological species identification. The thoraxes and abdomens including the blood meals of the individual females were subsequently subjected to DNA isolation. The molecular marker cytochrome oxidase I (COI barcode) was applied to identify the species of the collected biting midges (GenBank accessions JQ683259-JQ683374). The blood meals were first screened with a species-specific cytochrome b primer pair for cow and if negative with a universal cytochrome b primer pair followed by sequencing to identify mammal or avian blood meal hosts.ResultsTwenty-four species of biting midges were identified from the four study sites. A total of 111,356 Culicoides biting midges were collected, of which 2,164 were blood-fed. Specimens of twenty species were identified with blood in their abdomens. Blood meal sources were successfully identified by DNA sequencing from 242 (76%) out of 320 Culicoides specimens. Eight species of mammals and seven species of birds were identified as blood meal hosts. The most common host species was the cow, which constituted 77% of the identified blood meals. The second most numerous host species was the common wood pigeon, which constituted 6% of the identified blood meals.ConclusionsOur results suggest that some Culicoides species are opportunistic and readily feed on a variety of mammals and birds, while others seems to be strictly mammalophilic or ornithophilic. Based on their number, dispersal potential and blood feeding behaviour, we conclude that Culicoides biting midges are potential vectors for many pathogens not yet introduced to Denmark.

Project description:BackgroundWithin the genus Culicoides (Diptera: Ceratopogonidae), the subgenus Avaritia is of particular interest as it contains a significant number of economically important vector species. Disagreements about the systematic classification of species within this subgenus have resulted in a taxonomic imbroglio.MethodsA molecular phylogeny of the subgenus Avaritia was conducted to test the existing systematic classification, which is based on phenetic assessment of morphological characters. Three nuclear ribosomal markers, internal transcribed spacer 1 and 2 (ITS1, ITS2), 5.8S, and three mitochondrial markers, cytochrome c oxidase subunit 1 and 2, and cytochrome b (cox1, cox2 and cytb), were obtained for 37 species of the subgenus Avaritia from all six biogeographical regions. Phylogenetic reconstructions using these genes independently and in combination were implemented using Bayesian inference analysis and maximum likelihood methods.ResultsPhylogenetic reconstructions gave strong support to several monophyletic groups within the subgenus Avaritia. Both C. actoni and C. pusillus formed a single clade with C. grahamii so their respective groups, the Actoni and Pusillus groups, have been merged with the Grahamii group. Some support was provided for the Boophagus and Jacobsoni groups. A group of species currently placed into the Orientalis group clustered in a clade with poor support. The Obsoletus group was defined as a sister clade to all other Avaritia groups. The clade including the Imicola group was well supported based on phylogenetic criteria.ConclusionsThis phylogenetic study combining five distinct molecular markers has provided meaningful insights into the systematic relationships of Culicoides (Avaritia) and highlighted future directions to continue the study of this subgenus. While the cox2 marker appeared to be useful to investigate closely related species, the 5.8S marker was highly conserved and uninformative. Further investigations including species absent from this work are needed to confirm the proposed systematic scheme. However, this systematic scheme can now serve as a foundation to investigate cryptic species affiliation within the subgenus. We advocate that future studies employ a combination of morphological and molecular analyses.

Project description:BackgroundIn Senegal, the last epidemic of African horse sickness (AHS) occurred in 2007. The western part of the country (the Niayes area) concentrates modern farms with exotic horses of high value and was highly affected during the 2007 outbreak that has started in the area. Several studies were initiated in the Niayes area in order to better characterize Culicoides diversity, ecology and the impact of environmental and climatic data on dynamics of proven and suspected vectors. The aims of this study are to better understand the spatial distribution and diversity of Culicoides in Senegal and to map their abundance throughout the country.MethodsCulicoides data were obtained through a nationwide trapping campaign organized in 2012. Two successive collection nights were carried out in 96 sites in 12 (of 14) regions of Senegal at the end of the rainy season (between September and October) using OVI (Onderstepoort Veterinary Institute) light traps. Three different modeling approaches were compared: the first consists in a spatial interpolation by ordinary kriging of Culicoides abundance data. The two others consist in analyzing the relation between Culicoides abundance and environmental and climatic data to model abundance and investigate the environmental suitability; and were carried out by implementing generalized linear models and random forest models.ResultsA total of 1,373,929 specimens of the genus Culicoides belonging to at least 32 different species were collected in 96 sites during the survey. According to the RF (random forest) models which provided better estimates of abundances than Generalized Linear Models (GLM) models, environmental and climatic variables that influence species abundance were identified. Culicoides imicola, C. enderleini and C. miombo were mostly driven by average rainfall and minimum and maximum normalized difference vegetation index. Abundance of C. oxystoma was mostly determined by average rainfall and day temperature. Culicoides bolitinos had a particular trend; the environmental and climatic variables above had a lesser impact on its abundance. RF model prediction maps for the first four species showed high abundance in southern Senegal and in the groundnut basin area, whereas C. bolitinos was present in southern Senegal, but in much lower abundance.ConclusionsEnvironmental and climatic variables of importance that influence the spatial distribution of species abundance were identified. It is now crucial to evaluate the vector competence of major species and then combine the vector densities with densities of horses to quantify the risk of transmission of AHS virus across the country.

Project description:IntroductionCulicoides biting midges (Diptera: Ceratopogonidae) are vectors of arboviral pathogens that primarily affect livestock represented by Schmallenberg virus (SBV), epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV). In Kenya, studies examining the bionomic features of Culicoides including species diversity, blood-feeding habits, and association with viruses are limited.MethodsAdult Culicoides were surveyed using CDC light traps in two semi-arid ecologies, Baringo and Kajiado counties, in Kenya. Blood-fed specimens were analysed through polymerase chain reaction (PCR) and sequencing of cytochrome oxidase subunit 1 (cox1) barcoding region. Culicoides pools were screened for virus infection by generic RT-PCR and next-generation sequencing (NGS).ResultsAnalysis of blood-fed specimens confirmed that midges had fed on cattle, goats, sheep, zebra, and birds. Cox1 barcoding of the sampled specimens revealed the presence of known vectors of BTV and epizootic hemorrhagic disease virus (EHDV) including species in the Imicola group (Culicoides imicola) and Schultzei group (C. enderleni, C. kingi, and C. chultzei). Culicoides leucostictus and a cryptic species distantly related to the Imicola group were also identified. Screening of generated pools (11,006 individuals assigned to 333 pools) by generic RT-PCR revealed presence of seven phylogenetically distinct viruses grouping in the genera Goukovirus, Pacuvirus and Orthobunyavirus. The viruses showed an overall minimum infection rate (MIR) of 7.0% (66/333, 95% confidence interval (CI) 5.5-8.9). In addition, full coding sequences of two new iflaviruses, tentatively named Oloisinyai_1 and Oloisinyai_2, were generated by next-generation sequencing (NGS) from individual homogenate of Culicoides pool.ConclusionThe results indicate a high genetic diversity of viruses in Kenyan biting midges. Further insights into host-vector-virus interactions as well as investigations on the potential clinical significance of the detected viruses are warranted.

Dataset Information

First record of Culicoides oxystoma Kieffer and diversity of species within the Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) biting midges in Senegal.

Publications

First record of Culicoides oxystoma Kieffer and diversity of species within the Schultzei group of Culicoides Latreille (Diptera: Ceratopogonidae) biting midges in Senegal.

Similar Datasets

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