Description of Culicoides (Culicoides) bysta n. sp., a new member of the Pulicaris group (Diptera: Ceratopogonidae) from Slovakia

Occurrence of Biting Midges (Diptera: Culicoides) on Dairy Farms in Eastern Slovakia in Relation to Abiotic Factors

Within the scope of our research, we have performed 59 trapping sessions and collected 15,756 biting midges from 20 species at four farms (Kluknava, Ostrov, Turňa nad Bodovou and Zemplínska Teplica), The most frequent types of captured insects were representatives of the Avaritia subgenus, C. obsoletus/C. scoticus, representing on average 85.1 % (13,295 individuals) of the fauna of the biting midges, with the exception of the farm in Ostrov where this group represented only 41.7 % of the fauna. At this particular farm, the most frequently trapped insects belonged to the Culicoides subgenus (54.1 %), in particular the C. bysta, C. lupicaris, C. newsteadi, C. Pulicaris and C. Punctatus species. During the trapping sessions, we monitored factors affecting the number of trapped biting midges, such as the temperature, relative air humidity and airflow rate: the air temperature during the trapping of the biting midges ranged from 9.8 to 26.2 °C; the relative air humidity ranged from 35.1 to 100 %; and the air flow rate ranged from no wind to a wind velocity of 8.2 m.s-1. However, in the final evaluation, we failed to observe a statistically significant correlation between the air flow and the number of trapped biting midges. The largest amounts of biting midges were trapped at temperatures ranging from 15.8 to 24.6 °C and at a relative air humidity ranging from 54.2 % to 68.6 %. While monitoring the seasonal dynamics of the physiological conditions of biting midge females at the selected farms, we confirmed that during the period from June to August, the most frequently trapped females were parous (50.1 %; 7,826 individuals). In addition, nulliparous females comprised 43.8 % (6,842 individuals) and were continuously trapped throughout the season (April— November).

Identifying potential candidate Culicoides spp. for the study of interactions with Candidatus Cardinium hertigii

Culicoides biting midges (Diptera: Ceratopogonidae) are vectors responsible for the transmission of several viruses of veterinary importance. Previous screens of Culicoides have described the presence of the endosymbiont Candidatus Cardinium hertigii (Bacteroidetes). However, any impacts of this microbe on vectorial capacity, akin to those conferred by Wolbachia in mosquitoes, are yet to be uncovered and await a suitable system to study Cardinium-midge interactions. To identify potential candidate species to investigate these interactions, accurate knowledge of the distribution of the endosymbiont within Culicoides populations is needed. We used conventional and nested PCR assays to screen Cardinium infection in 337 individuals of 25 Culicoides species from both Palearctic and Afrotropical regions. Infections were observed in several vector species including C. imicola and the Pulicaris complex (C. pulicaris, C. bysta, C. newsteadi and C. punctatus) with varying prevalence. Phylogenetic analysis based on the Gyrase B gene grouped all new isolates within 'group C' of the genus, a clade that has to date been exclusively described in Culicoides. Through a comparison of our results with previous screens, we suggest C. imicola and C. sonorensis represent good candidates for onward study of Cardinium-midge interactions.

Blood meal analysis: host-feeding patterns of biting midges (Diptera, Ceratopogonidae, Culicoides Latreille) in Slovakia

Biting midges of the genus Culicoides are vectors of important pathogens affecting domestic and wild animals and have played a major role in the re-emergence of new outbreaks of bluetongue (BTV) and Schmallenberg (SBV) viruses in Europe. To determine vector-host specificity, trophic preference from blood meal analysis is of major importance in the surveillance of arthropod-borne diseases. Of 28,752 specimens collected, we identified 17 Culicoides species and investigated a total of 48 host sequences from the blood meals. Culicoides obsoletus/C. scoticus, C. dewulfi, C. pulicaris, C. lupicaris, C. punctatus, C. newsteadi, C. riethi, and C. furcillatus were found to feed on mammals (cattle, horses, and humans), birds (domestic chickens), small rodents (Apodemus flavicollis), and hares (Lepus europaeus). To our knowledge, this is the first study investigating trophic preferences of Culicoides spp. in Slovakia. This study demonstrated that Culicoides species are able to feed on domesticated host vertebrates as well as birds, rodents, and humans.

Comprehensive characterisation of Culicoides clastrieri and C. festivipennis (Diptera: Ceratopogonidae) according to morphological and morphometric characters using a multivariate approach and DNA barcode

Biting midges are widespread around the world and play an essential role in the epidemiology of over 100 veterinary and medical diseases. For taxonomists, it is difficult to correctly identify species because of affinities among cryptic species and species complexes. In this study, species boundaries were examined for C. clastrieri and C. festivipennis and compared with six other Culicoides species. The classifiers are partial least squares discriminant analysis (PLS-DA) and sparse partial least squares discriminant analysis (sPLS-DA).The performance of the proposed method was evaluated using four models: (i) geometric morphometrics applied to wings; (ii) morphological wing characters, (iii) "Full wing" (landmarks and morphological characters) and (iv)  "Full model" (morphological characters-wing, head, abdomen, legs-and wing landmarks). Double cross-validation procedures were used to validate the predictive ability of PLS-DA and sPLS-DA models. The AUC (area under the ROC curve) and the balanced error rate showed that the sPLS-DA model performs better than the PLS-DA model. Our final sPLS-DA analysis on the full wing and full model, with nine and seven components respectively, managed to perfectly classify our specimens. The C. clastrieri and C. festivipennis sequences, containing both COI and 28S genes, revealed our markers' weak discrimination power, with an intraspecific and interspecific divergence of 0.4% and 0.1% respectively. Moreover, C. clastrieri and C. festivipennis are grouped in the same clade. The morphology and wing patterns of C. clastrieri and C. festivipennis can be used to clearly distinguish them. Our study confirms C. clastrieri and C. festivipennis as two distinct species. Our results show that caution should be applied when relying solely on DNA barcodes for species identification or discovery.

Towards modernizing the taxonomy of Mediterranean Culicoides using classical morphology, mtDNA barcoding, and MALDI-TOF MS protein profiling

Culicoides biting midges (Diptera: Ceratopogonidae) are a highly successful group of small (1-3 mm) hematophagous flies, infamous for the role they play as biological vectors for numerous pathogens of veterinary significance. The principal aim of the national animal disease surveillance program of Israel is to be able to rapidly sort and identify live field-captured insects including Culicoides for arbovirus screening. In this exploratory study, three identification methods-classical morphology, DNA barcoding, and MALDI-TOF MS-were applied simultaneously to individuals of 10 Culicoides species that commonly attack livestock in Israel. The strengths and limitations of the three methods are compared and evaluated. In essence, the CO1 barcoding and MALDI-TOF MS results closely matched those of classical morphology. Furthermore, at a higher level and in strong accordance with recognized subgenera, the 10 species, in the reconstructed phylogenies, coalesced into multiple deeper-branched monophyletic clades. However, some discrepancies between the molecular and protein profiling results did occur and proved difficult to assess in terms of taxonomic significance. This difficulty underscores how tricky it is to establish clear species limits when methods involving borderline cutoff values and similarity indices are used as a taxonomic aid. An added shortcoming of the pluralistic triple-method approach is that a significant percentage of the species-level depositions in the GenBank and BOLD databases are misidentified, hindering structured comparison and interpretation of the morphological and molecular results obtained. Aspects of the unresolved taxonomy of various biting midge assemblages within the Mediterranean basin, including minor changes to the Israeli Culicoides checklist, are discussed in light of the methods applied. It is observed that the direct access that classical morphology provides to the external environment (or species niche) is indispensable to the full and correct interpretation (and application) of concomitant molecular and protein profiling results. The Culicoides taxonomy of the future ought to be fully integrative, during which the assimilation of modern methodological advances should strengthen-rather than undermine-the morphological foundations laid down during the 260-year Linnaean epoch.

Update of the Culicoides (Diptera: Ceratopogonidae) species checklist from Algeria with 10 new records

BACKGROUND

The Culicoides fauna of Algeria has been historically investigated, leading to the description of many new species by Kieffer in the 1920s, Clastrier in the 1950s or Callot in the 1960s and to a comprehensive inventory by Szadziewski in the 1980s. The emergence of bluetongue in the late 1990s enhanced Culicoides collections made in the country over the last two decades, but information remained mostly unpublished. The aim of this study is therefore to provide a comprehensive and updated checklist of Culicoides biting midge species in Algeria.

METHODS

The literature (published and grey, in French and in English) from 1920 to date on Culicoides collections in Algeria was collected and analyzed in the light of the current taxonomic and systematic knowledge and methods. Fresh Culicoides material was also analyzed using light/suction trap collections carried out from November 2015 to September 2018 in nine localities of the 'wilayah' of Tiaret (northwestern Algeria). Slide mounted specimens were identified morphologically using the interactive identification key IIKC and original descriptions. Specimens were then compared with non-type material originating from different countries and partly with type material.

RESULTS

A total of 13,709 Culicoides, belonging to at least 36 species within 10 subgenera, were examined leading to 10 new records in Algeria, including C. chiopterus, C. dewulfi, C. navaiae, C. grisescens, C. paradoxalis, C. shaklawensis, C. simulator, C. univittatus, C. achrayi and C. picturatus. These new records and all previous records provided by the literature review were discussed.

CONCLUSIONS

We propose a Culicoides checklist for the Algerian fauna of 59 valid species, including species mainly with a large Palaearctic distribution and a specific Mediterranean distribution, and only a few species from the Afrotropical region. Among them, several species, mainly of the subgenera Avaritia and Culicoides, are confirmed or probable vectors of arboviruses important in animal health.

Barcoding of the Genus Culicoides (Diptera: Ceratopogonidae) in Austria-An Update of the Species Inventory Including the First Records of Three Species in Austria

Ceratopogonidae are small nematoceran Diptera with a worldwide distribution, consisting of more than 5400 described species, divided into 125 genera. The genus Culicoides is known to comprise hematophagous vectors of medical and veterinary importance. Diseases transmitted by Culicoides spp. Such as African horse sickness virus, Bluetongue virus, equine encephalitis virus (Reoviridae) and Schmallenberg virus (Bunyaviridae) affect large parts of Europe and are strongly linked to the spread and abundance of its vectors. However, Culicoides surveillance measures are not implemented regularly nor in the whole of Austria. In this study, 142 morphologically identified individuals were chosen for molecular analyses (barcoding) of the mitochondrial cytochrome c oxidase subunit I gene (mt COI). Molecular analyses mostly supported previous morphologic identification. Mismatches between results of molecular and morphologic analysis revealed three new Culicoides species in Austria, Culicoidesgornostaevae Mirzaeva, 1984, which is a member of the Obsoletus group, C. griseidorsum Kieffer, 1918 and C. pallidicornis Kieffer, 1919 as well as possible cryptic species. We present here the first Austrian barcodes of the mt COI region of 26 Culicoides species and conclude that barcoding is a reliable tool with which to support morphologic analysis, especially with regard to the difficult to identify females of the medically and economically important genus Culicoides.

Blood-meal analysis of Culicoides (Diptera: Ceratopogonidae) reveals a broad host range and new species records for Romania

BACKGROUND

Culicoides biting midges are potential vectors of different pathogens. However, especially for eastern Europe, there is a lack of knowledge on the host-feeding patterns of this vector group. Therefore, this study aimed to identify Culicoides spp. and their vertebrate hosts collected in a wetland ecosystem.

METHODS

Culicoides spp. were collected weekly from May to August 2017, using Biogents traps with UV light at four sites in the Danube Delta Biosphere Reserve, Romania. Vectors and hosts were identified with a DNA barcoding approach. The mitochondrial cytochrome c oxidase subunit 1 was used to identify Culicoides spp., while vertebrate hosts were determined targeting cytochrome b or 16S rRNA gene fragments. A maximum likelihood phylogenetic tree was constructed to verify the biting midge identity against other conspecific Palaearctic Culicoides species. A set of unfed midges was used for morphological confirmation of species identification using slide-mounted wings.

RESULTS

Barcoding allowed the species identification and detection of corresponding hosts for 1040 (82.3%) of the 1264 analysed specimens. Eight Culicoides spp. were identified with Culicoides griseidorsum, Culicoides puncticollis and Culicoides submaritimus as new species records for Romania. For 39 specimens no similar sequences were found in GenBank. This group of unknown Culicoides showed a divergence of 15.6-16.3% from the closest identified species and clustered in a monophyletic clade, i.e. a novel species or a species without reference sequences in molecular libraries. For all Culicoides spp., nine mammalian and 24 avian species were detected as hosts. With the exception of C. riethi (n = 12), at least one avian host was detected for all Culicoides spp., but this host group only dominated for Culicoides kibunensis and the unknown Culicoides sp.. The most common host group were mammals (n = 993, 87.6% of all identified blood sources) dominated by cattle (n = 817, 70.6%).

CONCLUSIONS

Most Culicoides spp. showed a broad host-feeding pattern making them potential bridge vectors. At the same time, new records of biting midge species for Romania, as well as a potentially unknown Culicoides species, highlight the lack of knowledge regarding the biting midge species and their genetic diversity in eastern Europe.

Genetic diversity of Culicoides species within the Pulicaris complex (Diptera: Ceratopogonidae) in Turkey inferred from mitochondrial COI gene sequences

Identification of Culicoides (Diptera: Ceratopogonidae) biting midges to species has become important due to their potential role in the transmission of arboviruses such as bluetongue virus, bovine ephemeral fever virus, Akabane virus, African horse sickness virus, epizootic haemorrhagic disease virus and Schmallenberg virus. In several studies, molecular tools, used for the identification of biting midges, revealed the presence of cryptic and undescribed species especially within Pulicaris complex. The presence of cryptic species within species complexes raise questions about their role in viral disease transmission as there are apparent differences in the vectorial capacity between closely related species. In this study, we analyzed the mitochondrial DNA cytochrome oxidase I (COI) gene sequences of species within the Pulicaris complex present in Turkey and determined their phylogenetic relationships. Twenty-one haplotypes within the already described species C. pulicaris P1, C. lupicaris, C. lupicaris L2, C. newsteadi, C. newsteadi N1, C. punctatus, C. fagineus F2 and C. flavipulicaris were determined from the study areas. The molecular analysis revealed further two haplotypes belonging to new non-described cryptic species named as C. lupicaris L3 and Culicoides WBS corresponding to C. lupicaris and Fagineus complex which diverged by 17.9% to 25.7% and 18.7% to 31.8%, respectively from other species in the subgenus Culicoides. Genetic divergence within species was <2.0% and phylogenetic analyses of the COI dataset revealed 22 different monophyletic separate clades within two major cluster. The results of this study emphasize the applicability of COI sequences as a diagnostic marker for differentiating Culicoides species and revealing cryptic species.