title: Survey of blackfly (Diptera: Simuliidae) annoyance levels and abundance along the Vaal and Orange Rivers, South Africa.
abstract: Blackflies (Diptera: Simuliidae) are pests in the livestock and labour-intensive farming systems  along the major rivers in South Africa. Since 1995, blackflies have been controlled in the  Orange River with the larvicide Bacillus thuringienses var. israelensis (Bti). During 2006-2007, the views of livestock farmers concerning blackfly annoyance were determined by means of questionnaires. The results of the questionnaires were substantiated by seasonal abundance  surveys of the sub-adult stages of blackflies, conducted in 2007 at 13 sites in the Orange River  and 11 sites in the Vaal River. More than half (52%) of the 39 participating farmers along  the Orange River and 79% of the 52 participating farmers along the Vaal River stated that  they experienced severe blackfly problems. The majority of farmers were unaware of the  availability of products that could be used to protect their animals against blackfly attacks  and were willing to be involved in blackfly research. High numbers of blackfly sub-adult  stages found in both rivers supported the high annoyance levels reported by the respondents.  Simulium chutteri, Simulium damnosum s.l., Simulium hargreavesi, Simulium adersi and Simulium alcocki were identified at Christiana and Delportshoop on the Vaal River, whilst S. chutteri, S. damnosum  s.l., S. adersi,  S. alcocki and Simulium gariepense were identified at Marksdrift and Ses Bridge on the Orange River. Despite the extensive control of blackflies, farmers still experience problems and this contention is supported by surveys conducted along the rivers.
authors: Parasites, Vectors and Vector-borne Diseases, Agricultural Research Council, Onderstepoort Veterinary Institute, South Africa . debeerc@arc.agric.za
authors: Chantel J
authors: CJ
authors: de Beer
authors: Karin
authors: K
authors: Kappmeier Green
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis; D003625:Data Collection; D007299:Insect Bites and Stings / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary*; D007300:Insect Control; D007814:Larva; D058751:Livestock; D011156:Population Density; D011679:Pupa; D045483:Rivers; D012843:Simuliidae / Q000502:physiology*; D013019:South Africa / Q000453:epidemiology; D013045:Species Specificity; D011795:Surveys and Questionnaires