The Bioscientist (May 2013)
Ecology and Biting Activity of Simulium Damnosum Complex in Nigeria: A Review
Abstract
Dipterous insects of Simulium damnosum (Theobald) species complex transmit the parasite, Onchocerca volvulus which causes human onchocerciasis commonly called river blindness. S. damnosum breeds mainly in fast flowing, well-oxygenated water bodies. Its distribution is not even across Nigeria as there is correlation with basic geology. This is because the riverine conditions which create suitable breeding sites for the vector are most common where the African Precambrian basement rock is exposed to break the flow of water and create rapids. Ecological parameters such as water temperature, water pH, dissolved oxygen, ammonia content, rainfall, current velocity, relative humidity and conductivity influence the breeding of S. damnosum complex in Nigeria. Ecological factors which influence the adults include wind, humidity and light. Biting activity is highly seasonal in Nigeria. It ceases for several months in the long dry season of the northern savannas when rivers stop flowing, or are reduced to trickles and resumes only when rivers run again in the rains. On the other hand, where the climate is almost uniform throughout the year and rivers run continuously, biting activity occurs all-year round. Biting occurs outdoors at any daylight hour although each species may have its preferred time.
