BACKGROUND Documentation of the species composition of Anopheles mosquitoes and characterization of larval breeding sites is of major importance for the implementation of larval control as part of malaria vector control interventions in Ethiopia. The aims of this study were to determine the Anopheles larval species composition, larval density, available habitat types and the effects of related environmental and physico-chemical parameters of habitats in the Ghibe River basin of southwestern Ethiopia. METHODS Anopheles larvae were sampled from November 2014 to October 2016 on a monthly basis and 3rd and 4th instars were identified microscopically to species. The larval habitats were characterized based on habitat perimeter, water depth, intensity of light, water current, water temperature, water pH, water turbidity, distance to the nearest house, vegetation coverage, permanence of the habitat, surface debris coverage, emergent plant coverage, habitat type and substrate type. RESULTS In total, 9277 larvae of Anopheles mosquitoes and 494 pupae were sampled from borrow pits, hoof prints, rain pools, pools at river edges, pools in drying river beds, rock pools, tire tracks and swamps. Anopheles larval density was highest in pools in drying river beds (35.2 larvae per dip) and lowest in swamps (2.1 larvae per dip) at Darge, but highest in rain pools (11.9 larvae per dip), borrow pits (11.2 larvae per dip) and pools at river edges (7.9 larvae per dip), and lowest in swamps (0.5 larvae per dip) at Ghibe. A total of 3485 late instar Anopheles mosquito larvae were morphologically identified. Anopheles gambiae sensu lato was the primary Anopheles mosquito found in all larval habitats except in swamps. Temperature at the time of sampling and emergent vegetation, were the most important variables for Anopheles mosquito larval density. Anopheles gambiae density was significantly associated with habitats that had smaller perimeters, were sunlit, had low vegetation cover, and a lack of emergent plants. Generally, Anopheles mosquito larval density was not significantly associated with water pH, water temperature, water turbidity, algal content, and larval habitat depth. CONCLUSION Different species of Anopheles larvae were identified including An. gambiae s.l., the main malaria vector in Ethiopia. Anopheles gambiae s.l. is the most abundant species that bred in most of the larval habitat types identified in the study area. The density of this species was high in sunlit habitat, absence of emergent plants, lack of vegetation near habitat and habitats closer to human habitation. Rainfall plays a great role in determining the availability of breeding habitats. The presence of rain enable to create some of the habitat types, but alter the habitats formed at the edge of the rivers due to over flooding. Controlling the occurrence of mosquito larvae through larval source management during the dry season, targeting the pools in drying river bed and pools formed at the edge of the rivers as the water receded can be very crucial to interrupt the re-emergence of malaria vectors on the onset of rainy season.

中文翻译：

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埃塞俄比亚西南部吉贝河盆地两个地方的按蚊幼虫物种组成和繁殖栖息地的特征。

背景技术记录蚊子的按蚊种类组成和幼虫繁殖场所的特征对于在埃塞俄比亚实施幼虫控制作为疟疾媒介控制干预措施的一部分具有重要意义。这项研究的目的是确定埃塞俄比亚西南部吉卜河流域的按蚊幼虫的种类组成，幼虫密度，可用的生境类型以及相关生境的环境和理化参数的影响。方法2014年11月至2016年10月，按月对按蚊幼虫进行采样，并在显微镜下鉴定出3龄和4龄幼虫。根据栖息地的周长，水深，光照强度，水流，水温，水的pH值，水的浊度，到最近房屋的距离，植被覆盖率，栖息地的永久性，表面碎片覆盖率，紧急植物覆盖率，栖息地类型和基质类型。结果总共从借坑，蹄印，雨水池，河边的水池，干河床的水池，岩石水池，轮胎履带和沼泽中取样了9277只蚊子幼虫和494个p。在达格河中，河床干燥时，按蚊的幼虫密度最高（每浸35.2幼虫），在沼泽中最低（每浸2.1幼虫），但在雨水池中（每浸11.9幼虫），借坑（每浸11.2幼虫）最高。河流边缘的水池（每只幼虫7.9尾），吉贝河的沼泽中最低（每只幼虫0.5尾）。从形态学上共鉴定出3485只晚龄按蚊的幼虫。冈比亚按蚊是除沼泽以外在所有幼虫生境中发现的主要按蚊。采样时的温度和出现的植被是按蚊蚊虫幼虫密度的最重要变量。冈比亚按蚊的密度与周长较小，日光照射，植被覆盖率低和缺乏萌芽植物的栖息地显着相关。通常，按蚊的幼虫密度与水的pH值，水温，水的浊度，藻类含量和幼虫的栖息深度没有显着相关。结论确定了不同种类的按蚊幼虫，包括An。gambiae sl，埃塞俄比亚的主要疟疾传播媒介。冈比亚按蚊sl是在研究区域确定的大多数幼虫栖息地类型中繁殖的最丰富的物种。在阳光下的栖息地中，该物种的密度很高，没有出苗的植物，栖息地附近和靠近人类居住的栖息地都没有植被。降雨在确定繁殖栖息地的可用性方面起着重要作用。降雨的存在能够创造一些生境类型，但由于洪水泛滥，会改变河流边缘形成的生境。在枯水期通过幼虫源管理控制蚊虫幼虫的发生，以干燥的河床中的水池和河流边缘形成的水池为目标，因为水的后退对于中断疟疾媒介在地上的重新出现可能是非常关键的。雨季来临。降雨在确定繁殖栖息地的可用性方面起着重要作用。降雨的存在能够创造一些生境类型，但由于洪水泛滥，会改变河流边缘形成的生境。在枯水期通过幼虫源管理控制蚊虫幼虫的发生，以干燥的河床中的水池和河流边缘形成的水池为目标，因为水的后退对于中断疟疾媒介在地上的重新出现可能是非常关键的。雨季来临。降雨在确定繁殖栖息地的可用性方面起着重要作用。降雨的存在能够创造一些生境类型，但由于洪水泛滥，会改变河流边缘形成的生境。在枯水期通过幼虫源管理控制蚊虫幼虫的发生，以干燥的河床中的水池和河流边缘形成的水池为目标，因为水的后退对于中断疟疾媒介在地上的重新出现可能是非常关键的。雨季来临。