The effect of extreme environmental temperature spikes on mosquito longevity, fertility and ability to transmit viruses

背景和新颖性寿命、繁殖力和媒介能力是蚊子地理范围和它们传播的病毒的流行病学的核心因素。通常，这些特征要么在高度受控的实验室条件下进行研究，要么在没有实验的情况下在野外环境中进行更宽松的观察。在果蝇中，雄性果蝇的绝育温度通常比它们的致死极限低几度，导致环境导致它们的地理范围受到限制。相反，在叮咬蚊子的库蚊中，热浪提高了病毒的能力。在这个项目中，学生将结合现场收集和实验室实验来了解自然热波对两个英国本土物种：库蚊和Ochlerotatus detritus的影响。1)在实验室，学生将对蚊子群体实施具有英国代表性的热波热冲击，并评估其对死亡率和生育力的影响，从而能够估计热耐力。2)根据这些结果，将对群体蚊子实施亚致死(热波代表)温度。然后将用Usutu病毒攻击蚊子，以调查环境诱导的媒介能力。3)热浪过后，将从野外现场收集野生淡色库蚊和未成熟的Ochlerotatus幼虫。4)在实验停机期间，学生将接受气候建模方面的培训，并使用他们的实验结果来模拟这两个物种在英国的热范围、地理限制和病毒传播，无论是现在还是未来的气候情景。时间作为气候变化的直接结果，蚊子的生存范围目前正在迅速变化。一些热带地区的蚊子正在消失，那里的气温正在上升，降雨量正在减少。相反，温度蚊子正在向极地传播，带来了重要的动物和人类病毒。它们面临的不同环境条件将决定它们新的地理分布范围。由于气候变化，全球气温、热浪、湿度和降水模式发生了广泛而不均匀的变化，导致蚊子及其病毒普遍向极地迁移，远离一些温度过高、降雨量过低的热带地区，转向更温和的气候。例如，近年来，Usutu病毒(USUV)等人畜共患病病毒在整个欧洲大陆蔓延，2020年在英国发现了这种病毒。以前对不同昆虫的研究表明，热浪的影响截然不同，例如，与不育的雄性果蝇相比，叮咬的蚊子表现出更多的病毒传播，而雄性果蝇的不孕不育程度低于其致死极限。蚊子身上的类似效应可能会对媒介、病毒的地理范围以及谁和哪里处于危险之中产生影响。这项研究的目的是确定哪些与温度相关的性状，如寿命、生育力和媒介能力，会受到环境温度(热浪)的影响。我将在群体和野生捕获的个体中使用英国本土媒介物种库蚊和Ochlerotatus碎屑。通过对库蚊群体实施具有代表性的英国热浪热冲击，将确定温度对死亡率和生育力的影响，以评估热耐力并了解自然热浪的影响。在确定了可存活的亚致死温度后，蚊子将接受USUV的挑战，以评估环境诱导的媒介能力可能性。然后，这些发现将与现场收集的库仑和

Background and noveltyLongevity, fertility and vector competence are central factors in the geographic range of mosquitoes and the epidemiology of the viruses they transmit. Typically, these traits are studied either in highly controlled laboratory conditions, or observed more loosely in field settings without experimentation. In Drosophila, males are often sterilised by temperatures several degrees lower than their lethal limit, resulting in environment-induced restriction of their geographic range. Conversely, in Culicoides biting midges, heatwaves increase competence for viruses. If present in mosquitoes, these would have contrasting effects on the ranges of vector and virus.ObjectivesIn this project, the student will combine field collection and laboratory experimentation to understand the effect of natural heat waves on two native UK species: Culex pipiens pipiens, and Ochlerotatus detritus.1) In the lab, the student will administer UK-heatwave representative thermal-shocks to colony Culex mosquitoes and assess the effects on mortality and fertility, to enable estimation of thermal tolerance.2) Using these results, sub-lethal (heatwave representative) temperatures will be administered to colony mosquitoes. Mosquitoes will then be challenged with Usutu virus, to investigate environmentally induced vector competence.3) Wild Culex pipiens pipiens, and Ochlerotatus detritus immatures will be collected from field sites after heatwaves. Resultant adults will be assessed for fertility, mortality and challenged with Usutu virus.4) During experimental downtime, the student will be trained in climate modelling and use their experimental results to model the thermal range, geographic limitations, and virus transmission of these two species in the UK, both now and under future climate scenarios.TimelinessAs a direct consequence of climate change, the habitable range for mosquitoes is currently changing rapidly. Mosquitoes are disappearing from some tropical regions where temperatures are increasing and rainfall reducing. Conversely, temperature mosquitoes are spreading polewards, bringing with them important animal and human viruses. The different environmental conditions they face will determine their new geographic ranges.As a result of climate change, there has been extensive and uneven changes in global temperature, heatwave, humidity, and precipitation patterns leading to the general movement of mosquitoes and their viruses, poleward, away from some tropical regions where temperature is too high and rainfall too low toward more temperate climates. For example, in recent years, there has been a spread of zoonotic viruses such as Usutu virus (USUV) throughout mainland Europe, with its detection in the UK occurring in 2020. Previous studies in different insects have shown contrasting effects of heatwaves, e.g., biting midges showing increased transmission of viruses in comparison to male fruit flies that become sterile several degrees below their lethal limit. Similar effects in mosquitoes could have implications on the geographic ranges of vectors, viruses, and who and where is at risk. The aim of this study is to determine which relevant temperature-dependent traits, such as longevity, fertility, and vector competence, are affected by spikes in environmental temperature (heatwaves). I will use the native UK vector species Culex pipiens and Ochlerotatus detritus, both in colony and wild-caught individuals. By administering UK-heatwave representative thermal shocks to colony Culex mosquitoes, temperature effects on mortality and fertility will be determined to estimate thermal tolerance and understand the effect of natural heatwaves. Following the identification of survivable sub-lethal temperatures, mosquitoes will then be challenged with USUV to assess vector competence possibilities induced by the environment. These findings will then be combined with field collected Culex and