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

BACKGROUND: Species of the genus Culicoides Latreille, 1809 (Diptera: Ceratopogonidae) are mainly known as vectors of arboviruses such as bluetongue (BTV) and Schmallenberg (SBV). Among the known vectors, few species within the subgenus Culicoides Latreille, 1809 have been implicated in the transmission of BTV and SBV. Nevertheless, phylogenetic studies had revealed the presence of cryptic and undescribed species in Europe, raising questions about their vectorial role. A previous integrative study, associating morphology and barcode data, raised the hypothesis of the presence of undescribed species in Slovakia. The present study, combining morphological and molecular approaches, is aimed to support the hypothesis and a description of Culicoides bysta n. sp. is provided. METHODS: Series of male and female specimens were dissected and several of them were sequenced for the barcode region of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). Bayesian inference phylogenetic analyses based on 72 cox1 sequences of the species belonging to the Pulicaris group of the subgenus Culicoides, were carried out and the frequencies of intra/interspecific variations were analyzed. The morphology of abundant material of the new species (31 females and 12 males) was examined and compared with the paratypes of Culicoides boyi Nielsen, Kristensen & Pape, 2015 and with specimens of Culicoides pulicaris Linnaeus, 1758. For females, suture distances on the eyes were newly evaluated as a diagnostic character and for males we assessed a new measurement on the ninth tergite and on the apicolateral processes. RESULTS: Both phylogenetic analysis and barcode distances supported the distinct status of the new species, Culicoides bysta n. sp. described as a member of the Pulicaris group based on the morphology of males and females. The new species is closely related to C. boyi and C. pulicaris but can be distinguished on the basis of the wing pattern and the ratio between the two eye sutures. Both newly evaluated characters, i.e. eyes in females and male genitalia appeared to be diagnostic for distinguishing the new species described herein. CONCLUSIONS: The vector potential of the recently described species C. boyi and C. bysta n. sp. to transmit arboviruses, such as BTV and SBV, is unknown. When considering these two species as being close to C. pulicaris, the previous data, such as the vector implication for C. pulicaris in BTV transmission, should be revaluated in future.

First insights into indoor and outdoor Culicoides activity related to the risk period for Bluetongue virus transmission in Eastern Slovakia.

The epizootic of Bluetongue virus (BTV) throughout Europe in 2006 revealed insufficient knowledge regarding seasonal activities, endo/exophilic and endo/exophagic behaviour of the species of the Culicoides genus (Diptera: Ceratopogonidae). Although several studies have been carried out in Western Europe, bringing new knowledge of the above mentioned topics, there was still a gap to fill in Central Europe. Therefore, this study investigated seasonal variations in the indoor/outdoor Culicoides activity observed in the south-eastern Slovakia from 2012 to 2014, using a light-trapping method. In total, 52,741 Culicoides were collected and identified; majority of them were caught outdoors (82.6%), with the highest activity period being mid-June. The C. obsoletus/C. scoticus and C.punctatus species predominated, altogether representing 88.8 and 94.1% of the total indoor and outdoor collections, respectively. Positive correlation was observed between the temperature and the abundance, whereas no correlation with other studied factors was detected. In autumn, Culicoides activity was observed outdoors at temperatures ranging between-1.5°C and 9.3°C, whereas the indoor activity was detected at temperatures ranging between-3.9°C and 0°C. This demonstrated that the most significant BTV vectors in the studied area are C. obsoletus/C. scoticus. The C. dewulfi and C. chiopterus vectors appeared to be of lower significance. The period with the highest risk of the BTV transmission in Eastern Slovakia appeared to be mid-June. The autumnal Culicoides activity inside the cowsheds may be important for the assessment of virus overwintering. This study is the first to provide the data on indoor/outdoor behaviour of biting midges in Slovakia.

Morphological and molecular analysis of the genus Culicoides (Diptera: Ceratopogonidae) in Slovakia with five new records.

The biodiversity of Culicoides from eastern Slovakia was investigated by light trapping. An integrative taxonomy approach combining DNA barcode sequence and morphological analyses was used to accurately identify specimens. Five species were newly recorded from Slovakia: Culicoides picturatus Kremer & Deduit, C. gejgelensis Dzhafarov, C. clastrieri Callot et al., C. griseidorsum Kieffer and C. odiatus Austen. The checklist of the Culicoides species recorded from SK has been updated to 63 species and barcode sequence data is provided for 8 species not previously available on GenBank. Conflict between results from molecular and morphological analyses resulted in the discovery of some potentially new cryptic species and the inability of DNA barcodes to distinguish C. festivipennis Kieffer from C. clastrieri, C. salinarius Kieffer from C. manchuriensis Tokunaga and C. pallidicornis Kieffer from C. subfasciipennis Kieffer. These conflicts suggest further study is required to clarify the status of these species. 

Culicoides midges (diptera: ceratopogonidae) as vectors of orbiviruses in Slovakia.

In recent years, rapid spread of Culicoides-borne pathogens such as bluetongue (BT) and Schmallenberg viruses have been reported in Europe. In this study we examined the Culicoides populations in farms with wild and domestic ruminants in Eastern Slovakia with the aim to confirm the presence of biting midges serving as potential vectors of important pathogens. The main vector complexes were the Obsoletus complex (54%; n=4,209) and the Pulicaris complex (23%; n=1,796). To estimate the relative abundance of the cryptic species of the Obsoletus complex (Culicoides obsoletus, Culicoides scoticus and Culicoides montanus), we performed the multiplex polymerase chain reaction (PCR) based on ITS-2 and ITS-1 segments, on 125 midges randomly sampled. The relative abundance of C. obsoletus ranged from 5.26% in the farm with wild ruminants to 85.71% in another farm with cattle and sheep. A total of 112 pools of parous and gravid females belonging to the Obsoletus and Pulicaris complexes were tested for virus detection by the real-time reverse transcription polymerase chain reaction (RT-PCR) for BT virus, as well as for the Epizootic Hemorrhagic Disease Virus (EHDV), with negative results.