Dry Season Ecology of Malaria Vectors

疟疾媒介的旱季生态学

• 批准号: 9161731
• 负责人: Thomas E Wellems
• 金额: $ 8.42万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9161731
• 关键词: Address; Adult; African; Applied Research; Area; Basic Science; Behavioral; Biology; Coupled; Culicidae; Diapause; Disease Vectors; Distant; Ecology; Environmental Wind; Estivation; Flying body movement; Goals; Helium; Hydrocarbons; Intercept; Investigation; Laboratory Study; Location; Malaria; Molecular; Nature; Nomads; Outcome; Pattern; Photoperiod; Physiological; Population; Population Dynamics; Population Growth; Process; Publishing; Rain; Research; Sampling; Seasons; Shelter facility; Source; Spatial Distribution; Staging; Stream; Surface; Temperature; Time; Time Series Analysis; Variant; Water; Weather; Work; base; density; design; field study; frontier; insight; malaria transmission; migration; novel; novel strategies; reproductive; research study; response; success; vector; vector control

Despite extensive research on malaria for over a century, critical gaps remain in our understanding of the vectors; gaps that also limit our success in malaria control. We address some of the most critical gaps, namely the strategies used by African malaria vectors to persist through the long dry season without surface waters for several months. Combining field and laboratory studies, our results provide compelling evidence that malaria vectors persist through the dry season by a form of dormancy (aestivation) and also engage in wind-assisted long-distance migration probably over hundreds of kilometers. These fundamental facets of vector biology have been controversial and, until now, were ignored due to insufficient evidence. Conventional and novel malaria and vector control strategies cannot afford to ignore aestivation and long-distance migration as processes that may hinder or aid the ultimate outcome. This year, Nature has published our investigation of this problem based on the vector population dynamics. Using time series analysis, we extracted and compared the seasonal components of these dynamics between the vector species. Strong species-specific pattern provided signatures for the vector strategy of persistence. For example, density peaks during the dry season, coupled with a rapid population growth closely following the first rain provided evidence for aestivation in A. coluzzii, whereas total absence throughout the dry season coupled with with 6-8 weeks delay in timing of normal population growth of A. gambiae s.s. (after than of A. coluzzii) was consistent with long-distance migration. These results extend other studies we have carried out based on mosquito mark-release-recapture experiments, variation in spatial distribution, aerial mosquito sampling (100-200 m above ground), seasonal changes in reproductive activity, flight activity, cuticular hydrocarbons, and responses to changes in photoperiod and temperature. Based on these findings, experiments designed to (i) find the hidden shelters used by aestivating A. coluzzii mosquitoes during the dry season, (ii) Sample mosquitoes flying in high altitutdes (>100 m above ground) using traps tethered to helium filled balloons, (iii) determine the weather conditions promoting long-distance mosquito flights 10--200 m above ground), among others. Over the past year, we have been able to collect dozens of mosquitoes flying in the lower jet stream among them at least 14 A. gambiae s.l. More than 20 tanks of (balloon grade) helium have been used as part of this work. These results and ongoing studies using novel approaches provide fresh insights in malariology and vector biology. The findings that Anopheline vector of malaria and other disease vectors engage in long-distance flights and some are capable of dry-season dormancy open new frontiers of basic and applied research.

尽管对疟疾进行了一个多世纪的广泛研究，但我们对媒介的理解仍然存在重大差距。差距也限制了我们在疟疾控制方面取得的成功。我们解决了一些最关键的差距，即非洲疟疾媒介在没有地表水的情况下持续几个月的漫长旱季所采用的策略。结合实地和实验室研究，我们的结果提供了令人信服的证据，表明疟疾媒介通过一种休眠（夏眠）形式在旱季持续存在，并且还进行可能超过数百公里的风助长距离迁移。媒介生物学的这些基本方面一直存在争议，并且到目前为止，由于证据不足而被忽视。传统和新型疟疾和病媒控制策略不能忽视夏眠和长途迁徙，因为它们可能阻碍或有助于最终结果。 今年，《自然》杂志发表了我们基于媒介种群动态对这一问题的研究。使用时间序列分析，我们提取并比较了媒介物种之间这些动态的季节性成分。强烈的物种特异性模式为持久性载体策略提供了特征。例如，旱季期间密度达到峰值，加上第一场雨后种群数量迅速增长，为 A. coluzzii 夏眠提供了证据，而整个旱季完全消失，加上正常种群数量延迟了 6-8 周。 A. gambiae s.s. 的生长（在 A. coluzzii 之后）与长距离迁移一致。这些结果扩展了我们基于蚊标释放-再捕获实验、空间分布变化、空中蚊子采样（距地面 100-200 m）、生殖活动的季节性变化、飞行活动、表皮碳氢化合物和反应等进行的其他研究光周期和温度的变化。 基于这些发现，实验旨在 (i) 找到在旱季夏眠的 A. coluzzii 蚊子使用的隐藏庇护所，(ii) 使用系在充氦气球上的陷阱对在高空（距地面 >100 m）飞行的蚊子进行采样，(iii) 确定促进蚊子长距离飞行（距地面 10--200 m）的天气条件）等。在过去的一年里，我们已经收集到了数十只在低急流中飞行的蚊子，其中至少有 14 只 A. gambiae s.l.。作为这项工作的一部分，使用了 20 多个（气球级）氦气罐。 这些结果和正在进行的使用新方法的研究为疟疾学和媒介生物学提供了新的见解。疟疾和其他疾病媒介的按蚊媒介能够进行长途飞行，并且有些媒介能够进行旱季休眠，这一发现开辟了基础和应用研究的新领域。