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

蚊子的寿命、繁殖力和媒介能力是蚊子的地理范围和它们传播的病毒的流行病学的核心因素。通常，这些性状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田间环境中进行更松散的观察。在果蝇中，雄性果蝇通常在低于其致死极限几度的温度下绝育，导致其地理范围受到环境诱导的限制。相反，在库蠓叮咬蠓，热浪增加病毒的能力。ObjectivesIn this project，the student will combine联合收割机实地收集和实验室实验，以了解自然热浪对两种英国本土物种的影响：尖音库蚊和碎屑黄蚊。1）在实验室中，学生将管理英国热浪代表热休克库蚊殖民地和评估对死亡率和生育力的影响，以能够估计耐热性。2）使用这些结果，将亚致死（热浪代表性）温度施用于群体蚊子。然后将用库蚊病毒攻击蚊子，以研究环境诱导的媒介能力。3）在热浪后，将从野外地点收集野生尖音库蚊和未成熟的黄足库蚊。4）在实验停机期间，学生将接受气候建模的培训，并使用他们的实验结果来模拟英国现在和未来气候情景下这两个物种的热范围，地理限制和病毒传播。时效性作为气候变化的直接后果，蚊子的可居住范围目前正在迅速变化。蚊子正在从一些热带地区消失，那里的气温正在上升，降雨量正在减少。相反，温蚊正在向极地传播，带来重要的动物和人类病毒。它们所面临的不同环境条件将决定它们新的地理范围。由于气候变化，全球温度、热浪、湿度和降水模式发生了广泛而不均匀的变化，导致蚊子和它们的病毒普遍向极地移动，远离一些温度太高、降雨量太少的热带地区，向更温和的气候移动。例如，近年来，人畜共患病毒如埃图病毒（USUV）在整个欧洲大陆传播，2020年在英国发现。以前对不同昆虫的研究表明，热浪的影响截然不同，与雄性果蝇相比，叮咬性的蠓显示出病毒传播的增加，雄性果蝇在低于其致命极限的几度下变得不育。对蚊子的类似影响可能对病媒、病毒的地理范围以及谁和在哪里处于危险之中产生影响。 本研究的目的是确定哪些相关的温度依赖性特征，如寿命，生育力和载体能力，受到环境温度（热浪）峰值的影响。我将使用英国本土的媒介物种尖音库蚊和Ochlerotatus碎屑，无论是在殖民地和野生捕获的个人。 通过对库蚊群体进行英国热浪代表性热冲击，确定温度对死亡率和生育力的影响，以估计热耐受性并了解自然热浪的影响。在确定可存活的亚致死温度后，将用USUV对蚊子进行攻击，以评估环境诱导的媒介能力可能性。这些发现将与现场收集的库蚊和

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