LTREB: Resource pulses and the dynamics of rodents, ticks, and Lyme-disease risk in oak forests

Cary Institute Of Ecosystem Studies, Inc., Millbrook NY

Investigators

Abstract

Lyme disease is the most frequently reported vector-borne disease in the United States and is increasing in incidence and geographic range. Diagnostic tests are imperfect and treatments are sometimes ineffective. As a result, avoidance of exposure to the infected ticks that transmit the disease-causing bacteria is critical to protecting the public from this insidious disease. Avoidance of Lyme disease, in turn, requires knowing where and when infected ticks are expected to be abundant and risk therefore high. The continuation of these studies will allow researchers to better understand the effects of predators as well as environmental variation on mice populations, in order to predict long-term changes in risk of exposure to tick-borne diseases. The research will predict disease risk and will communicate this to the public, through multiple media outlets. The research team will continue to serve on relevant public policy boards at the local, state, and federal levels. Previous research has revealed that high abundance of acorns in the fall stimulates population growth of white-footed mice, resulting in high mouse density the following summer. Newly hatched larval ticks feed more successfully, and acquire pathogens more efficiently, from mice than from other hosts. Larval ticks feeding from abundant mice the summer following a high acorn year molt into nymphs one year later, resulting in high density of infected nymphs, and therefore high risk of Lyme disease, two summers following mast production. The investigators propose to continue research at six core study sites to maintain long-term data on: 1. Acorn and other tree seed production; 2. Population dynamics of mice, chipmunks, squirrels, and deer; 3. Population dynamics of larval, nymphal, and adult blacklegged ticks; 4. Infection prevalence of ticks with zoonotic pathogens; 5. Tick responses to specific climatic variables; and 6. Occurrence of predators and dilution hosts. Despite the predictability of Lyme-disease risk from past acorn production, new patterns and questions have recently emerged. Thus, five central objectives will be pursued: 1. Integrating host-seeking and attached tick subpopulations to develop full models of tick population dynamics under conditions of environmental variability; 2. Establishing a mechanistic basis for modeling climate effects on Lyme disease risk; 3. Determining long-term trends in tree seed production as a consequence of changes in climate, ontogeny, and the relative abundance of species; 4. Understanding top-down effects of mouse predators on rodent-tick interactions; and 5. Develop and iteratively evaluate forecasts for Lyme disease risk from the component parts. 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.