Department of Entomology and Plant Pathology, Auburn University, AL 36849, USA.
Biol Lett. 2012 Aug 23;8(4):567-9. doi: 10.1098/rsbl.2012.0075. Epub 2012 Mar 7.
In temperate regions, seasonal epidemics of many mosquito-borne viruses are triggered when mosquito populations shift from feeding on avian to mammalian hosts. We investigated effects of temperature on the timing of bird-to-mammal shifts using an 8 year dataset of blood-meals from a mosquito (Culex erraticus) in Alabama, USA. As expected, Cx. erraticus shifted from avian to mammalian hosts each year. The timing of the shift, however, varied considerably among years. Harshness of the preceding winter (chill accumulation) explained 93 per cent of the variation in the timing of bird-to-mammal shifts, with shifts occurring later in years following harsher winters. We hypothesize that winter temperatures drive the timing of bird-to-mammal shifts through effects on host reproductive phenology. Because mosquitoes target birds during the nesting season, and bird nesting occurs later in years following colder winters, later nesting dates result in a concomitant delay in the timing of bird-to-mammal host shifts. Global increases in winter temperatures could cause significant changes in the timing of seasonal host shifts by mosquitoes, with prolonged periods of epidemic transmission of mosquito-borne diseases.
在温带地区，当蚊子的种群从以鸟类为食转变为以哺乳动物为食时，许多由蚊子传播的病毒就会引发季节性流行。我们利用美国阿拉巴马州 8 年的蚊子（Culex erraticus）血液样本数据，研究了温度对鸟类向哺乳动物转变时间的影响。正如预期的那样，Cx. erraticus 每年都会从鸟类宿主转变为哺乳动物宿主。然而，转变的时间在不同年份之间有很大的差异。前一个冬季的严酷程度（寒冷积累）解释了鸟类向哺乳动物转变时间变化的 93%，较寒冷的冬季之后的年份中，转变发生得较晚。我们假设冬季温度通过影响宿主繁殖物候学来驱动鸟类向哺乳动物转变的时间。由于蚊子在筑巢季节以鸟类为目标，并且鸟类在较寒冷的冬季之后的年份中筑巢较晚，较晚的筑巢日期导致鸟类向哺乳动物宿主转变的时间相应延迟。冬季温度的全球升高可能导致蚊子季节性宿主转变的时间发生重大变化，从而延长蚊媒疾病的流行传播期。
