Institut de Recherche pour le Développement (IRD), UM1-CNRS 5290-IRD 224: Maladies Infectieuses et Vecteurs-Ecologie-Génétique, Evolution et Contrôle (MIVEGEC), Montpellier-France.
Parasit Vectors. 2011 Jun 27;4:121. doi: 10.1186/1756-3305-4-121.
An often confounding facet of the dynamics of malaria vectors is the aquatic larval habitat availability and suitable conditions under which they can thrive. Here, we investigated the impact of environmental factors on the temporal and spatial distribution of larval habitats of Anopheles arabiensis in different locations on La Reunion Island.
A retrospective examination was made from archival data which provided the complete enumeration of An. arabiensis breeding habitats in three distinct geographic zones--extending North-east, West and South of the island over 14 years, from January 1996 to December 2009. Data on the occurrence and the number of active larval habitats at each of a total of 4376 adjacent ellipsoid grid cells (216,506 square meters each) were used (1) to provide the geographic extent of breeding site availability from year to year and (2) to analyze associations with prevailing environmental factors, habitat types, and locations.
Anopheles arabiensis utilized a spectrum of man-made and natural aquatic habitats, most of which were concentrated primarily in the rock pools located in ravines and river fringes, and also in the large littoral marshes and within the irrigated agricultural zones. The numbers of breeding site per sampling grid differed significantly in different parts of the island. In contrast to an originally more widespread distribution across the island in the 1950s, detailed geographic analyses of the data obtained in the period extending from 1996-2009 showed an intriguing clustered distribution of active breeding sites in three discontinuous geographic zones, in which aquatic habitats availability fluctuates with the season and year. Seasonality in the prevalence of anopheles breeding sites suggests significant responsiveness to climatic factors.
The observed retreat of An. arabiensis distribution range to lower altitudinal zones (< 400 m) and the upward shift in the most remote littoral areas in the northeast and southwest regions suggest the possible influence of biogeographic factors, changes in land use and control operations. The results of this study would allow for a more rational implementation of control strategies across the island.
疟疾媒介动态的一个经常令人困惑的方面是水生生境的可用性以及它们能够茁壮成长的适宜条件。在这里，我们调查了环境因素对留尼汪岛不同地点阿拉伯按蚊幼虫栖息地的时空分布的影响。
从档案数据中进行了回顾性检查，这些数据提供了 1996 年 1 月至 2009 年 12 月 14 年间，在三个不同地理区域——岛的东北、西部和南部——完全列举的阿拉伯按蚊滋生地的数据。在总共 4376 个相邻的椭圆网格单元（每个单元 216506 平方米）中的每一个中出现和活跃幼虫栖息地数量的数据被用来：（1）提供年复一年繁殖地点可用性的地理范围；（2）分析与流行的环境因素、栖息地类型和位置的关联。
阿拉伯按蚊利用了一系列人造和自然水生栖息地，其中大部分主要集中在峡谷和河流边缘的岩石池中，也集中在大型沿海沼泽地和灌溉农业区。每个采样网格的滋生地数量在岛屿的不同地区有显著差异。与 20 世纪 50 年代在岛上更广泛分布的情况相反，对 1996-2009 年期间获得的数据进行的详细地理分析显示，活跃滋生地的分布呈三个不连续地理区域的有趣聚类分布，其中水生栖息地的可用性随季节和年份而波动。疟蚊滋生地流行的季节性表明对气候因素有显著的反应。
观察到阿拉伯按蚊分布范围退缩到较低海拔地区（<400 米），以及东北部和西南部最偏远沿海地区的上升，这表明可能受到生物地理因素、土地利用变化和控制行动的影响。这项研究的结果将使在整个岛屿上更合理地实施控制策略成为可能。
