Molecular Identification of Western European Species of Obsoletus Complex (Diptera: Ceratopogonidae) by an Internal Transcribed Spacer-1 rDNA Multiplex Polymerase Chain Reaction Assay

Abstract

In southern Europe, orbiviral diseases such as bluetongue (BT) have been assumed to have been largely transmitted by the classical Afro-Asian vector Culicoides imicola Kieffer (Diptera: Ceratopogonidae). Recent outbreaks have occurred in regions where C. imicola is normally absent, supporting the theory that other species belonging to the Obsoletus or Pulicaris complexes may play a role in BT virus transmission. Investigations of the ecology of the species within the former group are hampered by females of member species being extremely difficult to separate by classical morphology. To allow straightforward separation of these species in France, a multiplex polymerase chain reaction-based on internal transcribed spacer (ITS)-1 rDNA was developed to distinguish between Culicoides chiopterus Meigen, Culicoides dewulfi Goetghebuer, Culicoides montanus Shakirjanova, Culicoides obsoletus Meigen, and Culicoides scoticus Downes & Kettle. This tool will be useful in defining both the vector role and larval biotopes of these species in Europe.

Molecular differentiation of Culicoides biting midges (Diptera: Ceratopogonidae) from the subgenus Culicoides Latreille in Denmark

“…To ensure correct species identification, studies were initiated to develop molecular tools to identify different species within the subgenera Avaritia and Culicoides. Species of these two subgenera include the most common species in Northern Europe and are expected to include some of the potential bluetongue disease vectors (Gomulski et al 2005;Pagès and Sarto i Monteys 2005;Nolan et al 2007;Mathieu et al 2007;Pagès et al 2009;Nielsen and Kristensen 2011).…”

Changes of the abundance of Culicoides obsoletus s.s. and Culicoides scoticus in Southwest Germany identified by a PCR-based differentiation

“…Sequencing the ITS1 rDNA of 32 species of Culicoides for a phylogenetic analysis, C obsoletus, C. scoticus, and C. imicola clustered together, clearly separated from C. nubeculosus, C. puncticollis, and C. variipennis, the latter being classified as members of the Obsoletus complex or as members of the subgenus Monoculicoides (Perrin et al 2006). The ITS1 sequence has also been used in a multiplex PCR to distinguish Western European species of the Obsoletus complex from France (Mathieu et al 2007). …”

Bluetongue in Europe: vectors, epidemiology and climate change

“…and C. scoticus) cannot be consistently differentiated from one another on the basis of morphology (Pagès and Sarto I Monteys 2005), making estimation of the competence of the individual species difficult. The recent development of molecular techniques to differentiate the C. obsoletus group species (Mathieu et al 2007;Nolan et al 2007) promises to enable the measurement of BTV competence at the species level. The involvement of additional European Culicoides species in the transmission of BTV remains a possibility, and further work is required in this area.…”