Spatio-Temporal Distribution and Species Composition of Malaria Mosquitoes in Selected Districts of Benishangul Gumuz Regional State, Western Ethiopia

Abstract

The highest malaria transmission risk as stratified by annual parasite incidence, appears largely in Benishangul Gumuz region, the lowland and midlands of the western border with Sudan and South Sudan. The effectiveness of malaria vector control strategy depends on knowledge of factors that determine vector density and distribution, affecting adult Anopheles vector population dynamics and malaria transmission. This study aimed to investigate the spatial-temporal distribution and species composition of Anopheles mosquitos in western Ethiopia. The study was conducted in three districts of Assosa Zone (Assosa, Homosha and Bambasi), Benishangul Gumuz regional state. Adult and larva of Anopheles mosquitoes were collected using standard techniques after the long rainy season (October 2020-December 2020) and Dry season (January to February 2021). After collection, the data were analyzed using SPSS software. A total of 2063 Anopheles mosquitoes (1745 larvae and 318 adults) were collected during the study period and categorized into five Anopheles species (An. gambiae, An. funestus, An. coustani, An. ziemanni, and An. squamosus). Among all species An. gambiae s.l. (1548, 88.7%) was the predominant species while An. squamous (14, 0.8%) was the least dominant. From the three districts, the highest Anopheles mosquito specimens were collected from Bambasi (917, 52.6% larval and 126, 39.6% adult). And out of all collection months, the highest number of larvae and adult mosquitoes was collected during October. Among larval breeding habitats, pond was highly productive for Anopheles mosquitoes. Anopheles mosquitoes prefer to breed in all breeding sites, particularly temporary and sunlit habitats. Anopheles gambiae s.l. predominantly occurs during all seasons in its immature and mature stages, suggesting that malaria is a health problem in the area.