Species composition, monthly distribution and behaviour of adult Anopheles mosquitoes in areas under elimination setting, Dembia district, Northwestern Ethiopia

Abstract Background Despite of the progress made in scaling-up of the intervention tools in Ethiopia, malaria is still a public health problem in the country. This necessitates a continuous monitoring of the local vector species composition, monthly distribution and behaviour in order to follow up effectiveness vector control strategies in place. Thus, the aim of this study was to investigate species composition, distribution, and behaviour of Anopheles mosquitoes in selected localities of Dembia district.Methods Anopheles mosquito collection was conducted from June 2018 - May 2019 in selected areas of Dembia district by using Centers for Disease Control and Prevention (CDC) light traps, pyrethrum spray catches (PSCs), artificially constructed pit shelters and mouth aspirators. The sibling species of An. gambiae s.l were identified using a polymerase chain reaction (PCR). The blood source and sporozoite infection of Anopheles mosquitoes were determined using Enzyme linked immunosorbent assay (ELISA). The data were analyzed using SPSS version 20. ResultsAnopheles mosquitoes belonging to 11 species were identified from 2,055 field collected adult specimens during this study: An. pharoensis, An. arabiensis, An. coustani, An. demeilloni, An. cinereus, An. funestus, An. ardensis, and An. squamosus were identified from both Guramba Bata and Arebiya study sites while An. garnhami, An. christyi and An. nili were identified only from Guramba Bata. Anopheles pharoensis was the dominant species identified in both Arebiya and Guramba Bata study sites comprising 46.4%, whereas An. arabiensis were also comparably dominant in both study sites (38.3%). The density of outdoor host seeking and resting Anopheles mosquitoes were higher than indoor host seeking and resting Anopheles mosquitoes, however the difference was not statistically significant (p ≥ 0.05). The human blood indexes (HBI) of indoor and outdoor host seeking An. arabiensis were 17.4% and 15.3%, respectively. The overall sporozoite rate of An. arabiensis, An. pharoensis and An. coustani was 0.3%, 0.9% and 5.9% respectively.ConclusionsAnopheles pharoensis and An. arabiensis were the dominant species identified in the study area. Anopheles mosquitoes showed an exophagic, exophilic and zoophilic tendency in the study area. Vector control strategies targeting outdoor host seeking and resting Anopheles mosquitoes should be sought to achieve the desired malaria control and elimination program in the study area.