Regulating I. scapularis and the Role of Entomopathogenic Fungi

描述(申请人提供)：黑腿硬蜱，肩部硬蜱，是美国东北部和中西部至少三种由硬蜱传播的疾病的媒介：人类粒细胞无形体病、巴贝斯虫病和莱姆病，这是美国最重要的媒介传播疾病。减少这些疾病发病率的努力必须包括减少媒介人口的战略。肩胛虫的长期生活史数据表明，自然调节过程是适当的，这通常导致幼虫到成虫的累积死亡率超过95%。这些过程在很大程度上仍未确定，但在土壤表面普遍存在的昆虫病原真菌表明，它们可能是就地死亡的一个重要来源。肩峰轮虫在土壤表面度过了其两年寿命的大部分时间，而且有希望的实验室结果证明了这类真菌的杀螨特性。与目前效率低下或对环境有负面影响的做法相比，在扁虱生命周期的每个阶段增加自然死亡率的生物控制战略将是一个重大进步。拟议研究的主要目标是确定存在于发现扁虱的林地生境中的昆虫病原真菌，量化扁虱的感染率，并确定哪些季节模式和栖息地特征与真菌的存在有关。我们将使用培养、诱饵生物“诱捕”昆虫病原真菌和DNA提取相结合的方法，将代表着对自然界中昆虫病原真菌进行鉴定和量化的最全面的尝试。一旦记录了影响扁虱的各种昆虫病原真菌，进行了毒力分析，并证明了丰度的季节模式可能表明对特定生命阶段的不同影响，就有可能开发有效的生物控制策略，以加强自然调节机制。我们从土壤和扁虱样本中提取真菌DNA的能力，以及我们正在设计适当的引物来检测真菌的工作，已经揭示了昆虫病原真菌感染肩周炎的频率比之前认为的更频繁。此外，这将是第一次记录美国东北部昆虫病原真菌物种的季节分布的研究。通过研究这些真菌在调节我肩部的作用和了解这些生物的生态，我们预计会发展出自然的方法来进一步控制扁虱的种群和疾病的传播。目前的壁虱控制策略要么效率低下，要么对环境有害。利用自然界中已有的调控机制的生物控制战略可在适当的时候针对最易感染硬虱的阶段(S)，而不会对环境造成负面影响，从而对公众健康产生深远的影响。该项目将确定昆虫病原真菌是否可以作为这种生物防治策略的基础。这些真菌在实验室研究中显示出它们在环境中的分布和对我肩周炎的毒力方面的前景。减少杀虫剂的使用也可能带来长期的健康益处，而这些都是由于可获得有效的生防剂造成的。

DESCRIPTION (provided by applicant): The black-legged tick, Ixodes scapularis Say, is the vector of at least three tick-borne diseases in the northeastern and Midwestern US: human granulocytic anaplasmosis, babesiosis, and Lyme disease, the most important vector-borne illness in the country. Efforts to reduce the incidence of these diseases must encompass strategies to reduce vector populations. Long-term life history data for I. scapularis indicate that natural regulatory processes are in place that routinely account for cumulative larval to adult mortality rates in excess of 95%. These processes have remained largely unidentified but the ubiquity of entomopathogenic fungi at the soil surface, where I. scapularis spends most of its two-year lifespan, and promising lab results demonstrating the acaricidal properties of such fungi, suggest they may be a significant source of mortality in situ. A biocontrol strategy that augments natural mortality at each stage of the tick's life cycle would be a significant advance over current practices that are either inefficient or have negative impacts on the environment. The primary goals of the proposed study are to identify entomopathogenic fungi that exist in woodland habitats where ticks are found, to quantify infection rates in ticks, and determine what seasonal patterns and habitat features are associated with fungus presence. The combination of methods we will employ using culture, bait organisms to "trap" entomopathogenic fungi, and DNA extraction will represent the most comprehensive attempt to identify and quantify entomopathogenic fungi in nature. Once the variety of entomopathogenic fungi affecting ticks is documented, virulence assayed, and the seasonal patterns of abundance that may indicate differential impacts on particular life stages demonstrated, the potential exists to develop effective biocontrol strategies that augment natural regulatory mechanisms. Our ability to extract fungal DNA from soil and tick samples, along with our ongoing work to design appropriate primers to detect fungi, has already revealed that entomopathogenic fungi more frequently infect I. scapularis than previously thought. Furthermore, this will be the first study to document the seasonal distribution of entomopathogenic fungal species in the northeastern US. By investigating the role of these fungi in regulating I. scapularis and understanding the ecology of these organisms, we anticipate development of natural ways to impose further controls on tick populations and the spread of disease. Current tick control strategies are either inefficient or harmful to the environment. A biocontrol strategy that takes advantage of regulatory mechanisms already existing in nature could have a profound impact on public health by targeting the most susceptible tick stage(s), at the appropriate time, without imposing negative environmental impacts. This project will determine if entomopathogenic fungi can serve as the foundation for such a biocontrol strategy. These fungi show promise in terms of their distribution in the environment and virulence to I. scapularis in lab studies. Long- term health benefits might also accrue with the reduction in pesticide use those results from the availability of an effective biocontrol agent.