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。这些对人类的影响已经有了很好的描述，但是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触发不同形式生物损伤、导致野外适应性丧失和破坏生态系统所需的剂量率阈值。澄清这种不确定性的研究阐明了基本的生物过程，提供了对放射性污染对野生动物的生态影响的评估，并为管理放射性核素从工业、研究和医疗来源向环境的受管制释放的监测框架提供了证据基础。最近关于这一主题的许多研究都集中在切尔诺贝利禁区，该禁区是在1986年切尔诺贝利核事故发生后为限制人类进入辐射污染最严重的环境而设立的。这项工作引起了很大的争议：使用对比方法和研究生物体，一些结果表明野生动物受到目前辐射水平的影响很小或没有影响，而另一些数据表明，剂量率在远高于背景水平的情况下产生了实质性的有害影响。解决这些观点中哪一个是正确的是当前研究的主要目标。这个博士项目建立在我们过去两年半的研究基础上，结合了在切尔诺贝利隔离区的实地调查和低剂量慢性实验室暴露，以确定电离辐射对无脊椎动物的影响。我们最近从野外和实验室获得的数据表明，辐射暴露导致大黄蜂健康损失的剂量率远低于之前认为的有害剂量率。我们研究了常见的大黄蜂肠道寄生虫，炸弹Crithidia。我们的工作表明，辐射的这些影响部分是由辐射污染条件下寄生虫感染易感性升高介导的。本博士旨在研究辐射暴露对感染抵抗力的影响，主要集中在大黄蜂身上。它将把切尔诺贝利禁区的实地工作与斯特林大学与CEH兰开斯特大学合作的实验室工作结合起来。这个博士学位的确切目标是灵活的，可以根据申请人的兴趣和专业知识进行定制。下面的大纲是一个潜在的综合研究方案。研究问题：(1)辐射暴露对大黄蜂寄生虫易感性和感染毒力的影响如何受到其他环境压力的影响？(2)大黄蜂暴露于辐射后，诱导免疫反应的能力受损，在多大程度上导致寄生虫易感性升高？(3)辐射暴露后感染动态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也增加了对除炸弹梭菌以外的大黄蜂感染的易感性，包括其他肠道寄生虫、外寄生虫和病毒感染？(5)其他昆虫在受辐射照射后是否也会出现感染防御受损？

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?