Species Composition, Abundance and Population Structure of Malaria Vectors in Two Villages of Sudan

BackgroundFrequent monitoring of mosquito vector population is a strategy of great importance for reducing risks of disease occurrence. In Sudan, malaria is still a big threat to public health. Insecticide-based control has been undertaken for years, but there is no noticeable decrease of malaria infection nationwide.ObjectiveTo overcome this situation, a better understanding of the breeding ecology of the vectors is relevant. Here, we investigate the species composition of malaria vectors, seasonal abundance and population structure in two different villages.MethodologyMonthly samplings were performed in Abu Algoni (Sennar State) and Algerif West (Khartoum State) from June 2010 to May 2011. During each visit, immature stages were collected from potential breeding sites using dipping technique. In addition, adults were collected indoors from houses by aspiration and indoor pyrethrum spray methods. Mosquitoes were identified morphologically, the Anopheles gambiae complex diagnosed using PCR and the physiological status of females determined based on appropriate techniques. Environmental parameters namely temperature, rainfall and humidity were measured.ResultsA total of 4,932 mosquitoes comprising of 3047 larvae and 1885 adults (males and females combined) were sampled. Of these, 88.9% were collected from Abu Algoni while 11.1% were from Algerif West. Two species, An. rufipes and An. arabiensis were encountered. Anopheles rufipes was only found in Abu Algoni, while the latter was found in both villages, where it represented more than 99% of the total collection.Mosquitoes were found breeding in many types of places including canals, temporary pools of water, animal hooves, water from broken pipes, and water storage containers. No significant correlation was found between female and temperature (p>0.05). Significant correlation difference was observed between number of females of An. arabiensis and rainfall (p<0.05) and humidity (p<0.01).ConclusionsAnopheles arabiensis is the only member of An. gambiae complex detected in the present study. Seasonal abundance of An. arabiensis was observed with most during the wet rainy season in both villages. This could be associated with the availability of more breeding sites created by the rainfall. The majority were parous which indicates high survival rates and thus high vectorial capacity in transmitting malaria.