Journal of Medical Entomology (2005) 42, 1026-1034

N. Pagès and V. Sarto i Monteys (2005)
Differentiation of Culicoides obsoletus and Culicoides scoticus (Diptera: Ceratopogonidae) based on mitochondrial cytochrome oxidase subunit I
Journal of Medical Entomology 42 (6), 1026-1034
Abstract: Culicoides obsoletus (Meigen) and Culicoides scoticus Downes and Kettle (Diptera: Ceratopogonidae) are sibling species of the Obsoletus group. This group comprises species of biting midges that are suspect vectors of bluetongue virus (family Reoviridae, genus Orbivirus, BTV) and African horse sickness virus (family Reoviridae, genus Orbivirus, AHSV). BTV and AHSV have been isolated several times from females of this group, although it has not been possible to determine the particular species harboring the virus, because of the inability to clearly identify the females of each species based on morphology. Both sexes of C. obsoletus and C. scoticus midges from Catalonia and the Balearics (Spain) were sequenced for the mitochondrial gene cytochrome oxidase subunit I (COI), and these sequences were analyzed to determine intra- and interspecific genetic variability. Species-specific primers for C. obsoletus and C. scoticus were designed and a polymerase chain reaction (PCR)-based diagnostic assay based on the COI gene and using a hemi-nested PCR technique was developed for reliably distinguishing the females of both species. The species-specific PCR diagnostic was compared with morphological discrimination of C. obsoletus and C. scoticus females. The morphologic characters were not fully reliable.

Culicoides obsoletus (Meigen) y Culicoides scoticus Downes and Kettle (Diptera: Ceratopogonidae) son especies gemelas del grupo Obsoletus. Este grupo comprende especies de mosquitos ceratopogónidos sospechosos de actuar como vectores del virus de la lengua azul (familia Reoviridae, género Orbivirus, BTV) y del virus de la peste equina africana (AHSV). BTV y AHSV han sido aislados varias veces de hembras de este grupo, aunque no ha sido posible determinar qué especie concreta albergaba el virus, debido a la incapacidad de identificar con certeza las hembras de cada especie en base a su morfología. Ambos sexos de C. obsoletus y C. scoticus procedentes de Cataluña y de las islas Baleares (España) fueron secuenciados para el gen mitocondrial citocromo oxidasa subunidad I (COI) y se analizaron estas secuencias para determinar su variabilidad genética intra- e interespecífica. Se diseñaron cebadores específicos a nivel de especie para C. obsoletus y C. scoticus y se desarrolló un ensayo de diagnóstico mediante PCR basado en el gen COI y usando una técnica de PCR semianidada para distinguir con fiabilidad las hembras de ambas especies. Se comparó el diagnóstico de PCR con la discriminación morfológica de las hembras de C. obsoletus y C. scoticus. Los caracteres morfológicos no resultaron ser completamente fiables.
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Research topic(s) for pests/diseases/weeds:
identification/taxonomy

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Culicoides obsoletus		Spain (continental)
	Culicoides scoticus		Spain (continental)