Feeding behavior of Aedes (Aedimorphus) vexans arabiensis, a Rift valley fever virus vector in the Ferlo pastoral ecosystem of Senegal

Abstract

25Host-vector contact is a key factor in vectorial capacity assessment and thus the 26 transmission of mosquito-borne viruses such as Rift Valley Fever (RVF), an emerging zoonotic 27 disease of interest in West Africa. The knowledge of the host-feeding patterns of vector species 28 constitutes a key element in the assessment of their epidemiological importance in a given 29 environment. The aim of this work was to identify the blood meal origins of Aedes vexans 30 arabiensis Patton (Diptera: Culicidae), the main vector of RVF virus in the Ferlo pastoral 31 ecosystem of Senegal. Engorged female mosquitoes were collected in Younouféré in the 32 pastoral ecosystem in the Ferlo region during the 2014 rainy season. CDC light CO2-baited 33 traps were set at six sites for two consecutive nights every month from July to November. 34 Domestic animals present around traps were identified and counted for each trapping session. 35 Blood meal sources of engorged mosquitoes were identified using a vertebrate-specific 36 multiplexed primer set based on cytochrome b. Blood meal sources were successfully identified 37 for 319 out of 416 blood-fed females (76.68%), of which 163 (51.1%) were single meals, 146 38 (45.77%) mixed meals from two different hosts and 10 (3.13%) mixed meals from three 39 different hosts. Aedes vexans arabiensis fed preferentially on mammals especially on horse 40 compared to other hosts (P < 0.001). Proportions of single and mixed meals showed significant 41 temporal (P < 0.001) and spatial variations (P < 0.001) according to hosts availability. Aedes 42 vexans arabiensis shows an opportunistic feeding behavior depending on the host availability. 43 Results were discussed in relation with the Rift valley fever virus transmission and vector 44 involvement as well as its primary hosts. 45 Keywords: Rift valley fever, blood meal origins, Aedes vexans arabiensis, vertebrate-specific 46 multiplexed primers, Senegal. 47 Introduction 3 48 Rift Valley Fever (RVF) is an emerging zoonotic vector-borne viral infection [1] considered 49 as a major problem of public and veterinary health as evidenced by various outbreaks in Africa 50 [2-6]. This disease causes significant economic gaps in terms of animal deaths and economic 51 losses in the affected countries [7-9]. Mosquitoes of the genera Aedes and Culex are the main 52 vectors of RVF virus (RVFV) and transmission mainly occur during inter-epizootic periods [1]. 53 RVF is endemic in Senegal, especially in the Ferlo region [10, 11]. The transmission of the 54 virus is seasonal and insured by Ae. vexans arabiensis and Cx. poicilipes with peaks of 55 transmission at the end of the rainy season [12-14]. Disease control is difficult because 56 mosquito vectors are able to fly on long distances and escape the border sanitary barriers. 57 Moreover, vector control methods are not used to control RVF outbreaks because they are 58 costly and difficult to implement and could have important environmental and ecological 59 consequences. However, host such as cattle could be trea...