Studies on the morphometric characteristics of the Simulium damnosum complex in Uzo-Uwani, Enugu State, Nigeria

Abstract

Studies on the morphometric characteristics of the Simulium vectors of onchocerciasis were carried out in Uzo-Uwani Local Government Area (LGA), Enugu State, Nigeria, between September 2008 and January 2009, with the objectives of identifying the sibling species present in the area and comparing the result obtained with cytological studies earlier done in the area. It was also meant to relate fly types with the types of onchocerciasis present in the area. The Simulium flies were collected using human baits. Seventy-five (75) flies were subjected to morphometric examinations. The thorax length, antenna length, wing length, wing width and femur length were measured and the data obtained were transformed into ratios. The morphometric studies on the Simulium damnosum populations in Nkpologu showed a higher abundance of savanna flies (54) than forest flies (21) among those sampled. The classification was done using the thorax length/antenna length (TL/AL) ratio. Discriminate function analysis revealed that 96.0% of originally grouped cases were correctly classified. The result agreed with cytotaxonomic studies on Simulium done in the area which showed predominance of savanna flies. The implications of the results are discussed.