Occurrence of Culicoides species (Diptera: Ceratopogonidae) in the Khomas region of Namibia during the winter months

Abstract

Although African horse sickness (AHS) is considered to be endemic in Namibia, limited data on its Culicoides midge vector (Diptera: Ceratopogonidae) are available. The principal study objective was to determine the presence, species composition and the richness and diversity of Culicoides adults during the colder and drier months in the Khomas region of central Namibia. Five sites were selected, ranging from relatively high to low altitudes with high to low annual rainfall. Onderstepoort suction UV-light traps were used for Culicoides species collection and were run during the winter from 6 July to 21 September 2009. A relatively high diversity of 25 species from 9 091 Culicoides individuals were collected in 34 collections. The abundance of the proven vector of AHS virus, Culicoides imicola, varied from 94% near Windhoek at a high altitude and relatively higher annual rainfall, to 12% at the site situated farthest south-west, with the lowest altitude and annual rainfall. This relatively high Culicoides midge abundance, coupled with the presence of a cycling host (zebra) in the area, imply that AHS virus may overwinter in the Khomas region of Namibia.