Center for Environmental Research Leiden, Department of Environmental Biology, Leiden University, Einsteinweg 2, 2333 CC, Leiden, The Netherlands.
Division of Inland Water Systems, Deltares, 177, 2600 MH, Delft, The Netherlands.
Parasit Vectors. 2024 Jun 10;17(1):251. doi: 10.1186/s13071-024-06268-8.
Salinity, exacerbated by rising sea levels, is a critical environmental cue affecting freshwater ecosystems. Predicting ecosystem structure in response to such changes and their implications for the geographical distribution of arthropod disease vectors requires further insights into the plasticity and adaptability of lower trophic level species in freshwater systems. Our study investigated whether populations of the mosquito Culex pipiens, typically considered sensitive to salt, have adapted due to gradual exposure.
Mesocosm experiments were conducted to evaluate responses in life history traits to increasing levels of salinity in three populations along a gradient perpendicular to the North Sea coast. Salt concentrations up to the brackish-marine transition zone (8 g/l chloride) were used, upon which no survival was expected. To determine how this process affects oviposition, a colonization experiment was performed by exposing the coastal population to the same concentrations.
While concentrations up to the currently described median lethal dose (LD) (4 g/l) were surprisingly favored during egg laying, even the treatment with the highest salt concentration was incidentally colonized. Differences in development rates among populations were observed, but the influence of salinity was evident only at 4 g/l and higher, resulting in only a 1-day delay. Mortality rates were lower than expected, reaching only 20% for coastal and inland populations and 41% for the intermediate population at the highest salinity. Sex ratios remained unaffected across the tested range.
The high tolerance to salinity for all key life history parameters across populations suggests that Cx. pipiens is unlikely to shift its distribution in the foreseeable future, with potential implications for the disease risk of associated pathogens.
海平面上升加剧了盐度，这是影响淡水生态系统的一个关键环境线索。预测生态系统对这些变化的结构响应及其对节肢动物病媒地理分布的影响，需要进一步了解淡水系统中较低营养级物种的可塑性和适应性。我们的研究调查了通常被认为对盐敏感的蚊子 Culex pipiens 种群是否因逐渐暴露而适应了盐度。
在三个种群中进行了中观实验，以评估对盐度增加的生活史特征的反应，这些种群沿垂直于北海海岸的梯度排列。使用了高达咸淡水过渡区（8 g/l 氯化物）的盐浓度，在此浓度下预计不会有存活。为了确定这一过程如何影响产卵，通过将沿海种群暴露于相同浓度来进行殖民化实验。
尽管在产卵过程中，高达目前描述的半数致死剂量（LD）（4 g/l）的浓度令人惊讶地受到青睐，即使是最高盐浓度的处理也意外地被殖民化。种群之间的发育率存在差异，但盐度的影响仅在 4 g/l 及以上时才明显，仅导致 1 天的延迟。死亡率低于预期，在最高盐度下，沿海和内陆种群的死亡率仅为 20%，中间种群的死亡率为 41%。在测试范围内，性别比例不受影响。
所有关键生活史参数对盐度的高耐受性表明，Cx. pipiens 不太可能在可预见的未来改变其分布，这可能对相关病原体的疾病风险产生影响。
