Assessing the Impact of Radiation Exposure on Parasite Infection Susceptibility in Bumblebees in the Chernobyl Exclusion Zone

电离辐射对生物体是有害的。对人类来说，这些影响具有相对较好的特征，但关于野生动物如何受到辐射污染环境的影响的知识相对较少。主要的不确定性围绕着引发不同形式的生物损害、导致野外适应性丧失和破坏生态系统所需的剂量率阈值。澄清这一不确定性的研究揭示了基本的生物过程，评估了放射性污染对野生动物的生态影响，并为监管从工业、研究和医疗来源向环境排放的放射性核素的监测框架提供了证据基础。最近关于这一主题的研究主要集中在切尔诺贝利隔离区，该隔离区是在1986年切尔诺贝利核事故后设立的，目的是限制人类进入受辐射污染最严重的环境。这项工作引起了重大争议：使用对比方法和研究生物体，一些结果表明，野生动物受到当前辐射水平的影响很小，甚至没有影响，而其他数据表明，在剂量率没有远远高于本底水平的情况下，有很大的有害影响。确定这些观点中哪一个是正确的是当前研究的一个主要目标。这个博士项目建立在我们过去两年半的研究基础上，该研究结合了切尔诺贝利隔离区的实地工作和低剂量的长期实验室暴露，以确定电离辐射对无脊椎动物的影响。我们来自现场和实验室的最新数据表明，辐射暴露导致大黄蜂健康损失的剂量率明显低于之前认为的损害水平。我们研究了常见的大黄蜂肠道寄生虫Crithdia ombi的感染情况。我们的工作表明，辐射的这些效应在一定程度上是通过在辐射污染条件下提高寄生虫感染敏感性来调节的。本博士论文旨在研究辐射暴露对感染抗性的影响，主要集中在熊蜂身上。它将把切尔诺贝利隔离区的实地工作与斯特林大学的实验室工作结合起来，与CEH Lancaster合作。这一博士学位的确切目标是灵活的，可以根据申请者的兴趣和专业知识进行调整。以下概述是一个潜在的综合研究方案。研究问题：(1)辐射暴露对熊蜂寄生虫敏感性和感染毒力的影响是如何受其他环境应激源影响的？(2)辐射暴露后寄生虫易感性的增加在多大程度上是由于诱导免疫反应的能力受损？(3)辐射暴露后感染动力学的变化是否受到寄生虫特征变化的影响？(4)辐射暴露在多大程度上增加了除黄蜂以外的熊蜂感染的敏感性，包括其他肠道寄生虫、体外寄生虫和病毒感染。(5)其他昆虫在受到辐射照射后是否也受到感染防御能力的损害？

Ionising radiation is damaging to organisms. These effects are relatively well characterised for humans, but knowledge of how wildlife is affected by exposure to radiologically contaminated environments is comparatively sparse. Major uncertainty surrounds the dose rate thresholds necessary to trigger different forms of biological damage, cause fitness loss in the wild and disrupt ecosystems. Research to clarify this uncertainty sheds light on fundamental biological processes, provides assessment of the ecological impacts of radiological contamination on wildlife and provides the evidence base for the monitoring frameworks governing regulated releases of radionuclides into the environment from industrial, research and medical sources. Much recent research on this topic has focussed on the Chernobyl exclusion zone, established to restrict human access to the most radiologically contaminated environments after the Chernobyl nuclear accident in 1986. This work has generated major controversy: using contrasting methods and study organisms, some results suggest wildlife suffers minimal or no consequences from current radiation levels, whilst other data indicate substantial deleterious effects at dose rates that are not elevated far above background. Resolving which of these perspectives is correct is a major aim of current investigations.This PhD project builds on our research over the last 2.5 years that has combined fieldwork in the Chernobyl Exclusion Zone and low dose chronic laboratory exposures to determine the impact of ionizing radiation on invertebrates. Our recent data from the field and the lab suggests that radiation exposure drives fitness loss in bumblebees at dose rates significantly lower than those previously thought to be damaging. We studied infection by the common bumblebee gut parasite, Crithidia bombi. Our work indicates that these effects of radiation are in part mediated by elevated parasite infection susceptibility under conditions of radiological contamination.This PhD aims to investigate the impacts of radiation exposure on infection resistance, focussing principally on bumblebees. It will combine field work in the Chernobyl exclusion zone with laboratory work at Stirling University in collaboration with CEH Lancaster. The precise objectives of this PhD are flexible and could be tailored around the interests and expertise of the applicant. The following outline represents one potential integrated programme of research. Research Questions:(1) How is the impact of radiation exposure on bumblebee parasite susceptibility and infection virulence impacted by other environmental stressors?(2) To what extent is elevated parasite susceptibility following bumblebee radiation exposure driven by impaired ability to induce an immune response?(3) Are changes in infection dynamics following radiation exposure influenced by changes in parasite characteristics?(4) To what extent does radiation exposure also increase susceptibility to bumblebee infections other than C. bombi, including other gut parasites, ectoparasites and viral infections. (5) Do other insects also suffer impaired infection defence following radiation exposure?