Species composition, blood meal sources and insecticide susceptibility status of Culex mosquitoes from Jimma area, Ethiopia

Abstract

Different species of Culex mosquitoes are present in high numbers in many other countries in addition to sub-Saharan Africa and Asian countries. Culex mosquitoes are serious nuisance which also transmit a range of pathogens including several viruses such as West Nile virus, Saint Louis encephalitis, and Rift Valley fever, as well as parasites such as avian malaria, and filarial worms. In Ethiopia, unlike Anopheles mosquitoes, little effort was given to study habitat, species composition, blood meal sources and insecticide susceptibility status of Culex mosquitoes. Therefore, this study aimed to assess the species composition, their blood meal source and insecticide susceptibility status of Culex mosquitoes to some of selected insecticides in Jimma town southwest Ethiopia. Culicine mosquito larvae were collected using a standard dipper (by dipping) from a range of breeding sites and reared to adults. Species identification was carried out using standard keys. Bioassay tests were performed on adults to assess the susceptibility of Culex mosquitoes to insecticide-impregnated papers with Dichlorodiphenyltrichloroethane (DDT (4%), mlathion (5%), bendiocarb (0.1%), propoxur (0.1%), deltamethrin (0.05%) and pirimiphos-methyl (0.25) following World Health Organization Pesticide Evaluation Scheme (WHOPES) guideline. Moreover, 184 blood fed (BF) Culex mosquitoes were collected using aspirator from indoor and outdoor resting and assayed to assess blood meal sources using Enzyme-Linked Immunosorbent Assay (ELISA). The result of the study showed that among the collected Culex moquitoes, two species were identified as Culex quinquefasciatus and Cx antennatus whereas the remaining one could not be identified to species level. Culex mosquitoes were found to be resistant to DDT, malathion, bendiocarb, propoxur, and deltamethrin whereas susceptible to pirimiphos-methyl. The blood meal source analysis using Enzyme-Linked Immunosorbent Assay (ELISA) showed higher blood source of human (33.2%) than bovine (15.2%). Thus, the observed resistance to the most of the insecticides coupled with higher human blood meal source calls further studies to be carried out in Culex mosquito populations of Ethiopia.

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“…The transmission of diseases is caused by infected female mosquitoes, including dengue fever, malaria, filariasis, Japanese encephalitis, West Nile fever, and Zika. Dengue, chikungunya, zika, and yellow fever are all spread by Aedes aegypti mosquitoes [ 7 ], Wuchereria is spread primarily by Culex quinquefasciatus mosquitoes [ 8 ], and malaria is spread mainly through Anopheles stephensi mosquitoes [ 2 ]. The only known way to prevent or control these deadly illnesses is via efficient vector management [ 9 , 10 , 11 ].…”