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Groschupp S, Kampen H, Werner D. Occurrence of putative Culicoides biting midge vectors (Diptera: Ceratopogonidae) inside and outside barns in Germany and factors influencing their activity. Parasit Vectors 2023; 16:307. [PMID: 37653421 PMCID: PMC10472570 DOI: 10.1186/s13071-023-05920-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 08/09/2023] [Indexed: 09/02/2023] Open
Abstract
BACKGROUND After several years without bluetongue disease, a ruminant illness caused by Culicoides-borne bluetongue virus (BTV), two new autochthonous cases were reported in 2018 in Germany. By contrast, Schmallenberg virus (SBV), another Culicoides-borne virus pathogenic to ruminants, has continuously circulated in Germany since its first emergence in 2011. The disease outbreaks have triggered numerous studies on the biology of the Culicoides vectors, but many ecological details are still obscure. METHODS Culicoides biting midge species were collected with UV-light traps on 10 farms in Germany, with one trap inside and one trap outside barns on each of the farms. Traps were run once a week for 24 h from January to December 2019. Collected biting midges were morphologically identified, counted and statistically evaluated, with a focus on the Obsoletus Group and the Pulicaris Complex of the ceratopogonid genus Culicoides, which are believed to contain the major virus vectors. Temperature and relative humidity recorded at each trap were linked to the quantity of caught Culicoides. Correlations between relative Culicoides abundance and presence of livestock or type of husbandry were also investigated. RESULTS A total of 38,886 Culicoides biting midges were trapped, with most of them belonging to the Obsoletus Group (51.0%) and the Pulicaris Complex (38.8%). The majority of captured specimens were collected in traps inside the barns. Obsoletus Group individuals were caught from late January to the last week of December while Pulicaris Complex individuals were captured from the end of March to early December. The lowest average temperatures at which members of the two groups were collected were 10.7 °C and 12.8 °C, respectively. While temperature had a statistically significant effect on the activity of both the Obsoletus Group and the Pulicaris Complex, relative humidity only significantly affected the activity of the latter. The presence of livestock significantly influenced the number of captured Obsoletus Group, but not of Pulicaris Complex specimens. Inside the barns, no statistical difference was found between numbers of caught Obsoletus Group and Pulicaris Complex specimens in livestock holdings with deep litter and manure scraper or slatted floor husbandry systems. CONCLUSIONS The almost year-round presence of Obsoletus Group biting midges and the demonstrated high relative abundance of other potential Culicoides vector species inside barns suggest a high risk of indoor virus transmission to ruminants should BTV or SBV circulate locally. Appropriate structural, organisational and vector control measures to reduce biting midge exposure should be implemented.
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Affiliation(s)
- Sarah Groschupp
- Research Area 2 “Landscape Use and Governance”, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, 15374 Müncheberg, Germany
| | - Helge Kampen
- Friedrich-Loeffler-Institut–Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald, Germany
| | - Doreen Werner
- Research Area 2 “Landscape Use and Governance”, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, 15374 Müncheberg, Germany
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Kluiters G, Pagès N, Carpenter S, Gardès L, Guis H, Baylis M, Garros C. Morphometric discrimination of two sympatric sibling species in the Palaearctic region, Culicoides obsoletus Meigen and C. scoticus Downes & Kettle (Diptera: Ceratopogonidae), vectors of bluetongue and Schmallenberg viruses. Parasit Vectors 2016; 9:262. [PMID: 27146157 PMCID: PMC4857416 DOI: 10.1186/s13071-016-1520-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 04/20/2016] [Indexed: 11/10/2022] Open
Abstract
Background Some Palaearctic biting midge species (subgenus Avaritia) have been implicated as vectors of bluetongue virus in northern Europe. Separation of two species (C. obsoletus and C. scoticus) is considered difficult morphologically and, often, these female specimens are grouped in entomological studies. However, species-specific identification is desirable to understand their life history characteristics, assess their roles in disease transmission or measure their abundance during arboviral outbreaks. This study aims to investigate whether morphometric identification techniques can be applied to female C. obsoletus and C. scoticus individuals trapped at different geographical regions and time periods during the vector season. Methods C. obsoletus and C. scoticus were collected using light-suction traps from the UK, France and Spain, with two geographical locations sampled per country. A total of 759 C. obsoletus/C. scoticus individuals were identified using a molecular assay based on the cytochrome c oxidase subunit I gene. Fifteen morphometric measurements were taken from the head, wings and abdomen of slide-mounted specimens, and ratios calculated between these measurements. Multivariate analyses explored whether a combination of morphometric variables could lead to accurate species identification. Finally, Culicoides spp. collected in France at the start, middle and end of the adult vector season were compared, to determine whether seasonal variation exists in any of the morphometric measurements. Results The principal component analyses revealed that abdominal characteristics: length and width of the smaller and larger spermathecae, and the length of the chitinous plates and width between them, are the most reliable morphometric characteristics to differentiate between the species. Seasonal variation in the size of each species was observed for head and wing measurements, but not abdominal measurements. Geographical variation in the size of Culicoides spp. was also observed and is likely to be related to temperature at the trapping sites, with smaller individuals trapped at more southern latitudes. Conclusions Our results suggest that female C. obsoletus and C. scoticus individuals can be separated under a stereomicroscope using abdominal measurements. Although we show the length and width of the spermathecae can be used to differentiate between the species, this can be time-consuming, so we recommend undertaking this using standardized subsampling of catches. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1520-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- G Kluiters
- Liverpool University Climate and Infectious Diseases of Animals (LUCINDA) Group, Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Neston, Cheshire, CH64 7TE, UK.
| | - N Pagès
- Centre de Recerca en Sanitat 26 Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.,Present address: CIRAD, UMR CMAEE, F-97170, Petit-Bourg, Guadeloupe, France
| | - S Carpenter
- Vector-borne Viral Disease Programme, The Pirbright Institute, Woking, GU24 0NF, UK
| | - L Gardès
- Cirad, UMR15 CMAEE, F-34398, Montpellier, France.,INRA, UMR1309 CMAEE, F-34398, Montpellier, France
| | - H Guis
- Cirad, UMR15 CMAEE, F-34398, Montpellier, France.,INRA, UMR1309 CMAEE, F-34398, Montpellier, France
| | - M Baylis
- Liverpool University Climate and Infectious Diseases of Animals (LUCINDA) Group, Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Neston, Cheshire, CH64 7TE, UK.,National Institute for Health Research, Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, UK
| | - C Garros
- Cirad, UMR15 CMAEE, F-34398, Montpellier, France.,INRA, UMR1309 CMAEE, F-34398, Montpellier, France
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