Seasonal dynamics of Culicoides (Diptera: Ceratopogonidae) biting midges, potential vectors of African horse sickness and bluetongue viruses in the Niayes area of Senegal

Abstract

BackgroundThe African horse sickness epizootic in Senegal in 2007 caused considerable mortality in the equine population and hence major economic losses. The vectors involved in the transmission of this arbovirus have never been studied specifically in Senegal. This first study of the spatial and temporal dynamics of the Culicoides (Diptera: Ceratopogonidae) species, potential vectors of African horse sickness in Senegal, was conducted at five sites (Mbao, Parc Hann, Niague, Pout and Thies) in the Niayes area, which was affected by the outbreak.MethodsTwo Onderstepoort light traps were used at each site for three nights of consecutive collection per month over one year to measure the apparent abundance of the Culicoides midges.ResultsIn total, 224,665 specimens belonging to at least 24 different species (distributed among 11 groups of species) of the Culicoides genus were captured in 354 individual collections. Culicoides oxystoma, Culicoides kingi, Culicoides imicola, Culicoides enderleini and Culicoides nivosus were the most abundant and most frequent species at the collection sites. Peaks of abundance coincide with the rainy season in September and October.ConclusionsIn addition to C. imicola, considered a major vector for the African horse sickness virus, C. oxystoma may also be involved in the transmission of this virus in Senegal given its abundance in the vicinity of horses and its suspected competence for other arboviruses including bluetongue virus. This study depicted a site-dependent spatial variability in the dynamics of the populations of the five major species in relation to the eco-climatic conditions at each site.

Host preferences and circadian rhythm of Culicoides (Diptera: Ceratopogonidae), vectors of African horse sickness and bluetongue viruses in Senegal

“…The predominance of C. oxystoma and C. imicola in UV-light traps and horse-baited traps has previously been reported in the region (Diarra et al, 2014;Fall et al, 2015).This study showed a host preference of C. oxystoma and Culicoides species from the Avaritia sub-genus for horse as compared to sheep. Similar host preference for horse was found by Viennet et al(2012) for Culicoides species of veterinary significance using host-baited traps in the Palearctic region.…”

“…It should also be noted that only one C. nivosus specimen -a male -was found on the horse whereas 3 females, 2 of which were engorged, were found on sheep. During a previous study performed with a horse-baited trap (Fall et al, 2015), no engorged female of this species was found despite a high abundance in light-trap collections in the area (Diarra et al, 2014).…”

“…This stud farm was located in a forested area. This season was selected as optimal for Culicoides abundance, and this site was selected because C. imicola and C. oxystoma were both abundant (Diarra et al, 2014).The city of Thiès is in the Niayes area; it is characterised by depressions between dunes that flooded during the rainy season. These depressions are located from Dakar in the south to the Senegal River Delta in the north.…”

“…This species is abundant in light-traps in the Niayes area (Diarra et al, 2014), a region particularly affected by the previous epizootic outbreak of AHS in 2007; it is also aggressive towards horses (Fall et al, 2015). Furthermore, these studies collected up to 41…”

Schmallenberg virus in Culicoides Latreille (Diptera: Ceratopogonidae) populations in France during 2011-2012 outbreak

“…Previous studies in Italy recorded limited number of SBV RNA in C. imicola pools (Balenghien et al., ; Goffredo et al., ) while the species is considered as the proven vector of bluetongue virus in Africa and in the Mediterranean area (Goffredo et al., ; Mellor & Wittmann, ) and being very abundant (De Liberato, Purse, Goffredo, Scholl, & Scaramozzino, ; Diarra et al., ; Goffredo & Meiswinkel, ; Jacquet et al., ). Our study found SBV in two pools of C. imicola in Corsica where the species is abundant as well and peaks between end of August and October (Venail et al., ).…”