Species composition and relative abundance of the genus Culicoides (Diptera: Ceratopogonidae) in Romania

Background: Culicoidesbiting midges are vectors involved in the biological transmission cycle of important animal diseases such as bluetongue and African horse sickness. In Romania, the first outbreaks of bluetongue were reported in 2014, leading to increased activities within the existing entomological surveillance network. The main goals of the surveillance activities were the establishment of the vector free period in relation to animal trade and the identification ofCulicoidesspecies involved in the transmission of the pathogen. This study was conducted on the composition and relative abundance of the species belonging to the genusCulicoides(Diptera: Ceratopogonidae) in certain regions of Romania and provided the opportunity to update the existing checklist ofCulicoidesspecies of this country. Methods: The study was conducted in 33 of the 42 administrative units (counties), including a total of 659 catches, in 102 locations. The collections were carried out with UV blacklight suction traps (OVI type). The collected insects were preserved in 70% ethanol. Morphological insect identification was carried out using a stereomicroscope, according to established identification keys. In ten localities the relative abundance of the cryptic species of the Obsoletus complex was determined by multiplex PCR assay based on the ITS2 segment. The identification of theCulicoides chiopterus(Meigen) species by morphological examination was confirmed by PCR assay based on the ITS1 segment. Results: Eleven species were identified using morphological and PCR tools. The rest of the individuals were separated into five taxa. The species of the Obsoletus complex (grouping Culicoides obsoletus(Meigen) and Culicoides scoticus Downes & Kettle) were the most abundant, accounting for 59% of the total number of captured Culicoidesspp. Three of the identified species are mentioned, according to our knowledge, for the first time in Romania:Culicoides newsteadi Austen,Culicoides flavipulicaris Dzhafarov and Culicoides bysta Sarvasova, Kocisova, Candolfi & Mathieu. Conclusions: Our study demonstrates that theCulicoidesspecies most commonly cited as being involved in the transmission of arboviruses in Europe (i.e. bluetongue and Schmallenberg viruses) make up a high proportion of adultCulicoidestrapped in Romania.