title: Colonization of the Mediterranean basin by the vector biting midge species Culicoides imicola: an old story.
abstract: Understanding the demographic history and genetic make-up of colonizing species is critical for inferring population sources and colonization routes. This is of main interest for designing accurate control measures in areas newly colonized by vector species of economically important pathogens. The biting midge Culicoides imicola is a major vector of orbiviruses to livestock. Historically, the distribution of this species was limited to the Afrotropical region. Entomological surveys first revealed the presence of C. imicola in the south of the Mediterranean basin by the 1970s. Following recurrent reports of massive bluetongue outbreaks since the 1990s, the presence of the species was confirmed in northern areas. In this study, we addressed the chronology and processes of C. imicola colonization in the Mediterranean basin. We characterized the genetic structure of its populations across Mediterranean and African regions using both mitochondrial and nuclear markers, and combined phylogeographical analyses with population genetics and approximate Bayesian computation. We found a west/east genetic differentiation between populations, occurring both within Africa and within the Mediterranean basin. We demonstrated that three of these groups had experienced demographic expansions in the Pleistocene, probably because of climate changes during this period. Finally, we showed that C. imicola could have colonized the Mediterranean basin in the Late Pleistocene or Early Holocene through a single event of introduction; however, we cannot exclude the hypothesis involving two routes of colonization. Thus, the recent bluetongue outbreaks are not linked to C. imicola colonization event, but rather to biological changes in the vector or the virus.
authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.|CNRS, UMR 5290 Maladies Infectieuses & Vecteurs-Ecologie, Génétique, Ecologie, Contrôle (MIVEGEC), Université de Montpellier, Montpellier, France.|IRD, UR 224 MIVEGEC, BP 64501, Agropolis, 34394, Montpellier Cedex 5, France.
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authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
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authors.affiliation: Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester, UK.
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authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
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authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
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authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
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authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.|Plateforme de recherche CYROI, CRVOI, Sainte Clotilde, La Réunion, France.
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authors.affiliation: Department of Clinical Microbiology, Umea University, Umea, Sweden.
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authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
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authors.affiliation: Cirad, UPR AGIRs, RP-PCP, Harare, Zimbabwe.|Cirad, UPR AGIRs, Montpellier, France.|Department of Biological Sciences, Entomology, University of Zimbabwe, PO Box MP 167, Mount Pleasant, Harare, Zimbabwe.
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authors.affiliation: ISRA-LNERV, BP 2057, Dakar, Senegal.
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authors.affiliation: Kenya Agricultural and Livestock Research Organization Sericulture, PO Box 7816, Code 01000, Thika, Kenya.
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authors.affiliation: Departamento de Patología Animal, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain.
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authors.affiliation: UR Hortsys, Cirad, Montpellier, France.|Plant Health Department, ICIPE, Nairobi, Kenya.
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authors.affiliation: Medicine Faculty, Institute of Parasitology and Tropical Pathology (IPPTS), EA7292, 67000, Strasbourg, France.|EID Méditerranée, 34184, Montpellier, France.
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authors.affiliation: Laboratory of Zoology, University of Balearics (UIB), Palma de Mallorca, Spain.
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authors.affiliation: INRA UMR1309 CMAEE, 34398, Montpellier, France.|Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra (Cerdanyola del Vallès), Spain.|CIRAD, UMR CMAEE, 97170, Petit Bourg, Guadeloupe, France.
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authors.affiliation: Faculdade de Medicina Veterinária, CIISA, ULisboa, 1300-477, Lisboa, Portugal.
authors.forename: I
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authors.affiliation: Faculdade de Medicina Veterinária, CIISA, ULisboa, 1300-477, Lisboa, Portugal.
authors.forename: D W
authors.initials: DW
authors.lastname: Ramilo
authors.affiliation: CNRS, UMR 5175 CEFE, Université de Montpellier, Montpellier, France.|EPHE Campus CNRS, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
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authors.affiliation: EID Méditerranée, 34184, Montpellier, France.
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authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
authors.forename: F
authors.initials: F
authors.lastname: Stachurski
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authors.forename: G
authors.initials: G
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authors.lastname: Zimba
authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
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authors.lastname: Balenghien
authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
authors.forename: H
authors.initials: H
authors.lastname: Guis
authors.affiliation: CNRS, UMR 5290 Maladies Infectieuses & Vecteurs-Ecologie, Génétique, Ecologie, Contrôle (MIVEGEC), Université de Montpellier, Montpellier, France.|IRD, UR 224 MIVEGEC, BP 64501, Agropolis, 34394, Montpellier Cedex 5, France.
authors.forename: C
authors.initials: C
authors.lastname: Chevillon
authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.|ISRA-LNERV, BP 2057, Dakar, Senegal.
authors.forename: J
authors.initials: J
authors.lastname: Bouyer
authors.affiliation: CIRAD UMR15 CMAEE, 34398, Montpellier, France.|INRA UMR1309 CMAEE, 34398, Montpellier, France.
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mesh_terms: D000349:Africa; D000818:Animals; D001499:Bayes Theorem; D002467:Cell Nucleus / Q000235:genetics; D002519:Ceratopogonidae / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D005819:Genetic Markers; D005828:Genetics, Population; D007303:Insect Vectors / Q000235:genetics*; D019083:Mediterranean Region; D018895:Microsatellite Repeats; D008957:Models, Genetic; D058974:Phylogeography; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial; D005819:Genetic Markers
keywords: Culicoides imicola; approximate Bayesian computation; colonization; microsatellites; mitochondrial genes