title: Assessment of population genetic structure in the arbovirus vector midge, Culicoides brevitarsis (Diptera: Ceratopogonidae), using multi-locus DNA microsatellites.
abstract: Bluetongue virus (BTV) is a major pathogen of ruminants that is transmitted by biting midges (Culicoides spp.). Australian BTV serotypes have origins in Asia and are distributed across the continent into two distinct episystems, one in the north and another in the east. Culicoides brevitarsis is the major vector of BTV in Australia and is distributed across the entire geographic range of the virus. Here, we describe the isolation and use of DNA microsatellites and gauge their ability to determine population genetic connectivity of C. brevitarsis within Australia and with countries to the north. Eleven DNA microsatellite markers were isolated using a novel genomic enrichment method and identified as useful for genetic analyses of sampled populations in Australia, northern Papua New Guinea (PNG) and Timor-Leste. Significant (P < 0.05) population genetic subdivision was observed between all paired regions, though the highest levels of genetic sub-division involved pair-wise tests with PNG (PNG vs. Australia (FST = 0.120) and PNG vs. Timor-Leste (FST = 0.095)). Analysis of multi-locus allelic distributions using STRUCTURE identified a most probable two-cluster population model, which separated PNG specimens from a cluster containing specimens from Timor-Leste and Australia. The source of incursions of this species in Australia is more likely to be Timor-Leste than PNG. Future incursions of BTV positive C. brevitarsis into Australia may be genetically identified to their source populations using these microsatellite loci. The vector's panmictic genetic structure within Australia cannot explain the differential geographic distribution of BTV serotypes.
authors.affiliation: CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia. Maria.Onyango@csiro.au.|School of Medicine, Deakin University, 75 Pidgons Road, Waurn Ponds, Victoria, 3216, Australia. Maria.Onyango@csiro.au.
authors.forename: Maria G
authors.initials: MG
authors.lastname: Onyango
authors.affiliation: School of Biological Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia. Nigel.Beebe@csiro.au.|CSIRO Health & Biosecurity Ecosciences Precinct, 41, Boggo Road, Dutton Park, Queensland, 4102, Australia. Nigel.Beebe@csiro.au.
authors.forename: Nigel W
authors.initials: NW
authors.lastname: Beebe
authors.affiliation: NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, PMB, Wagga Wagga, New South Wales, 2650, Australia. david.gopurenko@dpi.nsw.gov.au.|Graham Centre for Agricultural Innovation, Locked Bag 588, Wagga Wagga, New South Wales, 2678, Australia. david.gopurenko@dpi.nsw.gov.au.
authors.forename: David
authors.initials: D
authors.lastname: Gopurenko
authors.affiliation: Northern Australia Quarantine Strategy, 1 Pederson Road, Marrara, Northern Territory, 0812, Australia. glenn.bellis@agriculture.gov.au.
authors.forename: Glenn
authors.initials: G
authors.lastname: Bellis
authors.affiliation: Graham Centre for Agricultural Innovation, Locked Bag 588, Wagga Wagga, New South Wales, 2678, Australia. Adrian.nicholas@dpi.nsw.gov.au.
authors.forename: Adrian
authors.initials: A
authors.lastname: Nicholas
authors.affiliation: International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya. M.ogugo@cgiar.org.
authors.forename: Moses
authors.initials: M
authors.lastname: Ogugo
authors.affiliation: International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya. A.Djikeng@cgiar.org.|Biosciences eastern and central Africa - ILRI Hub (BecA-ILRI Hub), ILRI, PO Box 30709, 00100, Nairobi, Kenya. A.Djikeng@cgiar.org.
authors.forename: Appolinaire
authors.initials: A
authors.lastname: Djikeng
authors.affiliation: International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya. s.kemp@cgiar.org.
authors.forename: Steve
authors.initials: S
authors.lastname: Kemp
authors.affiliation: CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia. Peter.Walker@csiro.au.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Walker
authors.affiliation: CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia. Jean-Bernard.Duchemin@csiro.au.
authors.forename: Jean-Bernard
authors.initials: JB
authors.lastname: Duchemin
mesh_terms: D000818:Animals; D001315:Australia; D001820:Bluetongue virus / Q000502:physiology; D002519:Ceratopogonidae / Q000235:genetics*; D004247:DNA / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population / Q000379:methods*; D007303:Insect Vectors / Q000235:genetics*; D018895:Microsatellite Repeats; D010219:Papua New Guinea; D049648:Timor-Leste
chemical_list: D004247:DNA