Marubini Elliot, Musekiwa Alfred, Maposa Innocent, Mazarire Theresa, Sekgele Windy, Mabaso Nondumiso, Dlamini Dumsani, Mdose Hetani, Kuonza Lazarus, Munhenga Givemore
South African Field Epidemiology Training Programme, National Institute for Communicable Diseases, Johannesburg, South Africa.
School of Health Systems and Public Health, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.
Malar J. 2025 Feb 20;24(1):52. doi: 10.1186/s12936-025-05287-9.
The South African government is now implementing winter larviciding as a supplementary vector control tool. To achieve effective larviciding programme there is a need to understand the distribution of the breeding sites of vectors and their corresponding ecology. This study aimed to determine larval breeding sites of anophelines and characterize the physicochemical properties of water that promote the proliferation of Anopheles arabiensis immature stages.
A desktop survey of water bodies was carried out followed by a physical search of potential Anopheles breeding sites. Anopheline larvae were sampled from breeding sites in January and April 2021. At each breeding site, physicochemical characteristics of the water, including pH, electrical conductivity, total dissolved solids, salinity and turbidity, were measured. The collected Anopheles larvae were reared to adults and identified to genus and species level using morphological and molecular techniques. Factors associated with the presence of An. arabiensis larvae in the breeding sites were determined.
Out of the 72 water bodies identified using desktop survey only 53% (n = 38/72) were identified through physical search. Of these 84% (n = 32/38) were positive for Anopheles larvae. A total of 598 Anopheles larvae were collected, of which 59.4% (n = 355/598) emerged into adults. Morphological identification of these adults, showed that the Anopheles gambiae complex accounted for 70% (n = 250/355) of the collections. From the 250 An. gambiae complex collected, 94% (235/250) were identified to species level by PCR and 6% (n = 15/250) failed to amplify. Of the 235 An. gambiae complex that were identified to species level, 62.5% (n = 147/235) were from January collections and 37.4% (n = 88/235) were from April collections. Molecular identification of the An. gambiae complex to species level showed predominance of An. arabiensis in April, 91% (n = 80/88). All physicochemical parameters differed significantly between the breeding site classes (p < 0.05 in all instances), except for electrical conductivity (p = 0.07). The aquatic habitats surveyed showed that the impermanency of the water bodies, neutral to alkaline pH, moderate salinity and low total dissolved solids were associated with the occurrence of An. arabiensis larvae.
This study showed that An. arabiensis primarily breed in small temporary water bodies characterized by neutral pH.
南非政府目前正在实施冬季灭蚊幼虫措施，作为一种辅助病媒控制工具。为了实现有效的灭蚊幼虫计划，有必要了解病媒繁殖地点的分布及其相应的生态环境。本研究旨在确定按蚊幼虫的繁殖地点，并描述促进阿拉伯按蚊幼虫阶段增殖的水体理化特性。
先对水体进行桌面调查，随后实地搜索潜在的按蚊繁殖地点。于2021年1月和4月从繁殖地点采集按蚊幼虫。在每个繁殖地点，测量水体的理化特性，包括pH值、电导率、总溶解固体、盐度和浊度。将采集到的按蚊幼虫饲养至成虫，并使用形态学和分子技术鉴定到属和种的水平。确定与繁殖地点中阿拉伯按蚊幼虫存在相关的因素。
在通过桌面调查确定的72个水体中，只有53%（n = 38/72）通过实地搜索被确认。其中84%（n = 32/38）的水体按蚊幼虫呈阳性。共采集到598只按蚊幼虫，其中59.4%（n = 355/598）羽化为成虫。对这些成虫的形态学鉴定表明，冈比亚按蚊复合体占采集总数的70%（n = 250/355）。在采集到的250只冈比亚按蚊复合体中，94%（235/250）通过PCR鉴定到种的水平，6%（n = 15/250）未能扩增。在鉴定到种水平的235只冈比亚按蚊复合体中，62.5%（n = 147/235）来自1月的采集样本，37.4%（n = 88/235）来自4月的采集样本。将冈比亚按蚊复合体鉴定到种水平的分子鉴定结果显示，4月阿拉伯按蚊占优势，为91%（n = 80/88）。除电导率外（p = 0.07），所有理化参数在不同繁殖地点类别之间均存在显著差异（所有情况下p < 0.05）。所调查的水生栖息地表明，水体的临时性、中性至碱性pH值、适度盐度和低总溶解固体与阿拉伯按蚊幼虫的出现有关。
本研究表明，阿拉伯按蚊主要在pH值为中性的小型临时性水体中繁殖。
