Cytotaxonomic identification of Simulium damnosum complex (Diptera: Simuliidae) in Oji River area of Enugu state, Nigeria

Simulium damnosum complex is the major vector of onchocerciasis in Africa. Very little is known about the S. damnosum complex sibling species in Nigeria. Cytotaxonomic studies were therefore carried out to determine the distribution of these cytospecies in Oji River Area of Enugu State, Nigeria. Larval samples were collected from eleven breeding sites. The larvae were fixed in Carnoy’s solution and chromosome preparations made in the laboratory. The cytospecies identified include S. squamosum (45.02%), S. yahense (30.58%), S. damnosum s.s. (21.65%) and S. sirbanum (2.75%). Their relative distributions were as follows: Oji Mile 2 (26.80%), Oji Ehuhe (19.59%), Oji Adu (17.18%), Oji Alum (22.34%) and Mmamu (14.09%). S. damnosum complex larval abundance was higher in the dry season (51.89%) compared to the rainy season (48.11%). This study has revealed the breeding of forest and savannah dwelling groups of S. damnosum s.l. involved in onchocerciasis transmission in the study area.