Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
Acta Trop. 2010 Jul-Aug;115(1-2):90-4. doi: 10.1016/j.actatropica.2010.02.008. Epub 2010 Feb 18.
Anopheles funestus is one of the major vectors of malaria in sub-saharan Africa. Because of several cycles of recurrent drought events that have occurred in the sahelian zone, this species had disappeared from this area since the 1970s following a disappearance of its specific breeding sites. Its comeback was, however, recently observed particularly in the Senegal River basin following the implementation of two dams. Because the implementation of hydro-agricultural and irrigation settings are suspected to be involved in the reestablishment of An. funestus populations and that paracentric inversions are involved in the adaptation to various environments, the present study was undertaken in 3 villages of the Senegal River basin (Keur Mbaye, Mbilor and Gankette Balla), (i) to study the chromosomal polymorphism of the newly established An. funestus populations in the Senegal River basin using paracentic inversions from ovarian nurse cells and (ii) their relationship with other populations of this species located in different environmental contexts (Dielmo in sudanian zone, Sankagne and Kouvar in northern sudano-guinean zone and Ngari in southern sudano-guinean zone) in order to know the key factors leading to their reestablishment in this area. Our results showed that the newly established An. funestus populations' exhibit low level of chromosomal polymorphism with two chromosomal inversions (the fixed 2Rs and the polymorphic 3La) out of the 9 paracentric inversions described up to now in An. funestus in Senegal. At population level, no significant deviation from Hardy-Weinberg equilibrium was observed for almost all inversions. Furthermore, significant genetic differentiation was revealed between the populations from the Senegal River basin and those from the sudanian and southern sudano-guinean zones and was not linked to geographical distance. However, the populations from the Senegal River basin were close or slightly differentiated to those from the northern sudano-guinean zone located within or near irrigated cultures. These observations suggest that the hydro-agricultural settings following the implementation of dams in the Senegal River were probably responsible to the comeback and the reestablishment of the An. funestus populations in this zone.
致倦库蚊是撒哈拉以南非洲地区疟疾的主要传播媒介之一。由于萨赫勒地区发生了几轮反复干旱事件，自 20 世纪 70 年代以来，由于其特定繁殖地的消失，该物种已从该地区消失。然而，最近在塞内加尔河盆地实施了两座大坝之后，这种物种又重新出现了。由于怀疑水利农业和灌溉设施的实施参与了致倦库蚊种群的重新建立，并且旁侧倒位涉及到对各种环境的适应，因此，本研究在塞内加尔河盆地的 3 个村庄（Keur Mbaye、Mbilor 和 Gankette Balla）中进行了研究，（i）使用卵巢滋养细胞中的旁侧倒位来研究塞内加尔河盆地新建立的致倦库蚊种群的染色体多态性，以及（ii）它们与位于不同环境背景下的该物种的其他种群（在苏丹区的 Dielmo、在北苏丹-几内亚区的 Sankagne 和 Kouvar 以及在南苏丹-几内亚区的 Ngari）之间的关系，以了解导致它们在该地区重新建立的关键因素。我们的结果表明，新建立的致倦库蚊种群的染色体多态性水平较低，只有两种染色体倒位（固定的 2Rs 和多态的 3La），而在塞内加尔的致倦库蚊中，目前已经描述了 9 种旁侧倒位。在种群水平上，几乎所有倒位都没有偏离 Hardy-Weinberg 平衡。此外，塞内加尔河盆地的种群与苏丹区和南苏丹-几内亚区的种群之间存在显著的遗传分化，与地理距离无关。然而，塞内加尔河盆地的种群与位于灌溉区或附近的北苏丹-几内亚区的种群密切相关或略有分化。这些观察结果表明，塞内加尔河实施大坝后进行的水利农业设置可能是导致该地区致倦库蚊种群重新出现和重新建立的原因。
