Culicine Mosquito Species Diversity, Host Feeding Preferences and Insecticide Resistance Status in Taita-Taveta County, Kenya
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Date
2020
Authors
Ngami, Munyao Vanessa
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Culicine mosquitoes are vectors of human disease-causing pathogens like lymphatic filariasis and several arboviruses such as dengue fever, chikungunya virus and so on. Due to intensifying land use land cover (LULC) with increasing pressure on natural environments because of urbanization and agricultural activities, there has been an increasing risk of mosquito-human contact leading to transmission of vector borne diseases. In recent years, along the coastal region, Kenya, there have been increased occurrences of emerging and re-emerging vector borne diseases, with subsequent social -economic concerns implications. Therefore, this study determined Culicine mosquito species abundance, diversity and their host feeding preferences in Taita -Taveta County, Coastal Kenya. A Cross sectional study design was adopted in this study. Entomological sampling was done in the months of March and October 2018, which are dry and wet season respectively. Adult mosquitoes were collected indoors and outdoors using CDC light traps and Backpack aspiration. The collected mosquitoes were sorted according to their sub-families as Anopheline and Culicine. The Culicine mosquitoes were identified morphologically into species and categorized according to their physiological status. The fully blood fed mosquitoes were tested for blood meal sources using Enzyme Linked Immunosorbent Assay (ELISA) for different hosts found within the peri -domestic environment mainly human, goat, chicken and bovine. For insecticide resistance characterization, mosquito larvae were collected using dipping sampling method, the mosquito larvae were reared into adults. The 3-5 old emergent mosquitoes were exposed to pyrethroids using WHO protocol. Three thousand two hundred and seventy-eight (3,278) mosquitoes were collected indoors (22.5%, n=738) and outdoors (77.5%, n=2,540). The collected Culicine mosquitoes were identified to be consisting of eighteen (18) species including; Aedes (7 species), Culex (8 species), Mansonia (2 species), Coquilletadia (1 species). Culex quinquefasciatus (69.1%) was the predominant species observed in all the six sites, though varied across the sites (χ2=85.5, df=5, P<0.001). Culex straitipes and Cx. Culicioma (0.03%) had the lowest numbers of mosquitoes. Overall, there was high mosquito species diversity (H) in outdoors (H = 2.4339) than in indoors (H =2.2523) with even distribution (EH) being higher in indoors (EH =0.9064) than outdoors (EH =0.8266). Of the mosquitoes collected, 1,241 mosquitoes were tested for blood meal sources. Majority of the blood meals sources identified were from multiple blood meal sources (51.6%), single hosts (41.3%) and least were unidentified (7.2%). There was significant difference of Human Blood Index between indoor and outdoor for Cx. Quinquefasciatus species (χ2=19.40, df=1, P<0.0001). Culex quinquefasciatus showed some existence of resistance to bediocarb, deltamethrin, DDT and fenitrothion, but were found to be susceptible to Permethrin. The study demonstrated that Culicine mosquitoes were highly zoophilic. It is therefore essential to evaluate the impact of zooprophylaxis on arboviruses transmission. There is a need for more studies on species distribution and abundance beyond what this study has accomplished and conduct vector competence and blood meal assays for a comprehensive assessment of lymphatic filariasis and arboviruses risk to public health in Taita-Taveta, Kenya.
Description
Research Thesis Submitted in Partial Fulfillment for the Award of Degree of Master of Science in Infectious Diseases (Parasitology) in the School of Medicine, Kenyatta University. March, 2020
Keywords
Culicine Mosquito, Species Diversity, Host Feeding Preferences, Insecticide Resistance Status, Taita-Taveta County, Kenya