SG: Abiotic constraints on the invasion of ticks and tick-borne pathogens across environmental gradients in Maine

University Of Maine, Orono ME

Investigators

Abstract

In recent decades, numerous hard-bodied tick species of medical and veterinary significance have spread dramatically beyond their historical ranges into more northern latitudes. This expansion has increased transmission of infectious diseases to humans, companion animals, and wildlife. Understanding the environmental conditions that constrain establishment and maintenance of tick populations at their northern range limits may enhance our ability to predict future range expansion. Further, better understanding of tick distribution will facilitate targeting vector management strategies to life-stages and times of year when ticks are most vulnerable. The goal of this project is to identify specific biological mechanisms by which abiotic factors limit the current northern geographic distribution of the blacklegged tick, an important disease vector in North America. A strong climate gradient in Maine, an emerging area of tick-borne disease transmission, will be used to understand the effects of temperature and precipitation on winter survival and seasonal host-seeking activity in the black-legged tick. In addition, the relationship between tick range expansion and spread of three tick-bourne pathogens will be examined. This project will provide training opportunities for numerous undergraduate and graduate students, particularly those belonging to groups traditionally underrepresented in STEM. Also, the researchers will organize public outreach focused on safe and effective personal tick protection practices. The project will integrate manipulative field experiments and observational field studies to test several hypotheses regarding environmental constraints on range expansion of the blacklegged tick, as well as implications of range expansion on the distribution of tick-borne pathogens. In particular, researchers will examine large-scale environmental gradients to better understand: 1) interacting effects of temperature and snow cover on blacklegged tick overwinter survival, 2) impacts of climate on tick host-seeking phenology, and 3) co-invasion dynamics of the blacklegged tick and three pathogens it transmits. These objectives will be addressed by establishing experimental tick overwinter survival assays and host-seeking behavioral assays at five field sites in Maine representing spanning a range of temperature and snowfall conditions. In addition, observational studies of off-host and on-host ticks in the same locations will be conducted at the same locations. The combination of manipulative field experiments and observational field studies utilized in this research effort will simultaneously isolate abiotic constraints on the current geographic distribution of the blacklegged tick while preserving the ecological realism of natural conditions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.