Regulating I. scapularis and the Role of Entomopathogenic Fungi

描述（由申请人提供）：黑腿蜱，肩突硬蜱，是美国东北部和中西部至少三种蜱传疾病的媒介：人粒细胞无形体病、巴贝虫病和莱姆病，莱姆病是该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病媒种群的战略。长期生活史资料表明，肩胛肌表明，自然调节过程是适当的，通常占累积幼虫到成虫死亡率超过95%。这些过程在很大程度上仍然是未知的，但昆虫病原真菌在土壤表面的普遍存在，在那里我。scapularis在其两年的生命期中度过了大部分时间，并且证明这种真菌的杀螨特性的有希望的实验室结果表明，它们可能是原位死亡的重要来源。在蜱虫生命周期的每个阶段增加自然死亡率的生物控制策略将是对目前效率低下或对环境产生负面影响的做法的重大进步。拟议研究的主要目标是确定存在于蜱虫栖息地的昆虫病原真菌，量化蜱虫的感染率，并确定与真菌存在相关的季节模式和栖息地特征。我们将采用的方法相结合，使用文化，诱饵生物“陷阱”昆虫病原真菌，DNA提取将代表最全面的尝试，以确定和量化昆虫病原真菌在自然界中。一旦记录了影响蜱虫的昆虫病原真菌的种类，测定了毒力，并证明了可能表明对特定生命阶段的不同影响的丰度的季节性模式，就有可能开发出增强自然调控机制的有效生物防治策略。我们从土壤和蜱样本中提取真菌DNA的能力，沿着我们正在进行的设计合适的引物来检测真菌的工作，已经揭示了昆虫病原真菌更频繁地感染I。比以前想象的要多。此外，这将是第一项记录美国东北部昆虫病原真菌物种季节分布的研究。通过研究这些真菌在调节I.通过对这些生物体的生态学研究，我们预计将开发出自然方法来进一步控制蜱虫种群和疾病传播。目前的蜱虫控制策略要么效率低下，要么对环境有害。利用自然界中现有的调控机制的生物防治策略可以在适当的时候针对最敏感的蜱虫阶段，对公共卫生产生深远的影响，而不会对环境造成负面影响。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。这些真菌在环境中的分布和对I.实验室研究中的肩胛肌。长期的健康利益也可能随着农药使用的减少而增加，这是由于有效的生物控制剂的可用性。

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.