Patterns and ecological mechanisms of the geographic range expansion of arthropod­-borne disease

This project will investigate the geographic range expansion of vector-borne pathogens from a landscape and community ecology perspective. A major focus of this effort will be the synthesis of epidemiological human case data and ecological field studies to identify and investigate environmental drivers of the movement of three tick-borne pathogens (Lyme disease, anaplasmosis, and babesiosis) in Maine. In particular, initial modeling studies will generate and test hypotheses regarding ecological processes responsible for the large-scale movement of infectious disease to novel environments, while complementary field studies will address the dual roles of land cover change (e.g., timber harvesting, plant invasions, land development) and climate change in mediating the establishment of the black-legged tick and associated pathogens within their introduced range.The scientific merit of this research is twofold. First, Maine has experienced a fivefold increase in the incidence of Lyme disease in humans over the past decade, particularly in the state's growing rural population of residents over the age of 65, and there is an urgent need to develop "eco-epidemiological" frameworks to understand risk of exposure. Second, notifiable tick-borne diseases provide a unique opportunity to understand ecological features that make landscapes susceptible to biological invasions, a consequential question for natural resource management in Maine; invasive species are becoming increasingly widespread and ecologically damaging aided by human activities. Mechanistic studies of invasion biology often are limited by low detection probabilities and the infeasibility of large-scale sampling, but due to CDC reporting requirements, emerging vector-borne diseases are associated with more comprehensive geo-located data sets compared to most invasive taxa, which can be exploited for basic ecological research.Specific aims are as follow:1)Generate and test hypotheses regarding ecological mechanisms driving the geographic expansion of three tick-borne diseases in Maine based on the distribution of human cases.2)Quantify the entomological risk of exposure to tick-borne pathogens across land use/land cover categories and gradients (e.g., timber harvesting, plant invasions, developed land).3)Experimentally assess the importance of weather/climate as constraints on recruitment and phenology of the black-legged tick.4)As additional external funding becomes available, conduct research on other questions related to the invasion ecology of arthropod vectors and their associated pathogens. This work at other locations will complement the focal projects ongoing in Maine.