Birds flyways and spread of Hyalomma ticks in Europe

This study modelled the probability of introduction of Hyalomma marginatum into Europe by predicting the potential migratory routes of 27 bird species and the probability to carry immatures of the tick. Flyways were modelled as a spatio-temporal feature, at weekly intervals, using satellite-derived data of temperature and vegetal phenology, together with cost surfaces derived from speed and direction of the wind (years 2002-2018). The probability of moulting of the engorged nymphs was modelled as a linear relationship of the daily sum of temperatures after tick introduction by birds. Positive probabilities of tick introduction extend the known northern range of permanent populations to central and west France, and large portions of central Europe. The flight of birds into an area and thence the risk of introduction of H. marginatum is very heterogeneous, sites receiving “waves” of different bird species at diverse moments of the year. Therefore, there is not a clear slice of time for introduction, as it depends on the modelled behaviour of the bird species. The probability of introduction into Baltic and Nordic countries is small. We hypothesize that conditions of warmer climate might support permanent populations of H. marginatum if a high number of immatures are introduced. Active surveys in risky territories, where the tick is not yet established, are advisable for a rapid intervention.本研究通过预测27种鸟类的潜在迁徙路线及其携带该蜱未成熟虫态的概率，构建了边缘璃眼蜱（Hyalomma marginatum）传入欧洲的风险概率模型。研究以周度时间步长将鸟类迁徙通道建模为时空特征，采用卫星遥感获取的气温与植物物候数据，结合基于2002-2018年风速与风向生成的迁徙成本曲面。饱食若蜱的蜕皮概率被建模为鸟类携带该蜱传入后，日气温累积总和的线性关系。蜱传入概率为正的区域，将该蜱永久种群的已知北部分布范围扩展至法国中西部以及欧洲中部大片区域。鸟类飞往某一区域的行为及由此引发的边缘璃眼蜱传入风险存在显著异质性：一年中不同时段，各站点会迎来不同鸟类的迁徙“浪潮”。因此不存在统一的传入时间窗口，其取决于各鸟类物种经建模得到的迁徙行为特征。波罗的海国家与北欧国家的蜱传入概率较低。我们提出假说：若有大量未成熟虫态被引入，气候变暖的环境条件或可支撑边缘璃眼蜱的永久种群定殖。建议在该蜱尚未定殖的高风险区域开展主动监测，以便实施快速干预措施。