Stabling and the protection of horses from Culicoides bolitinos (Diptera :Ceratopogonidae), a recently identified vector of African horse sickness

The stabling of horses at night reportedly offers protection from African h orse sickness and the most significant vector of the disease, Culicoides im icola Kieffer, has been shown to be exophilic. In certain high-lying region s of South Africa, however, C. bolitinos Meiswinkel, may be the major vecto r of the disease but its entry behaviour into stables is unknown. According ly, in the eastern Free State province of South Africa, light trap catches of C. bolitinos inside stables and outside, were compared. Two horse-baited stables, one traditional, and one modern, were used and combinations of st able (old/new), ceiling fans (on/off) and accessibility to Culicoides (stab le doors open/closed or windows gauzed/ungauzed) were investigated as treat ments. A total of 111,452 Culicoides of 26 species was collected on 60 trap nights; C. bolitinos was dominant (89.1% overall) with C. imicola second i n abundance (2.9%) . Outside catches were greater on warmer, drier, evening s but were suppressed by high wind speeds. Catches of C. imicola inside sta bles with doors open, or with windows ungauzed, were less than the numbers captured outside. In contrast, more C. bolitinos were caught in open stable s than outside, i.e. open structures may protect horses from the exophilic C. imicola, but may increase attack rates from the endophilic C. bolitinos. The closing of doors and the gauzing of windows, however, led to a 14-fold reduction in numbers of C. bolitinos and C. imicola entering stables. A we ll-gauzed 'traditional' stable was as effective as a closed 'modern' stable . Ceiling fans had no suppressant effect.