RAPID: Effects of spongy moth defoliation on blacklegged ticks

Cary Institute Of Ecosystem Studies, Inc., Millbrook NY

Investigators

Abstract

In the United States, blacklegged ticks are the main vectors of Lyme disease and several other diseases that afflict roughly 500,000 people each year. The abundance of these ticks is a major risk factor for human populations. Research that identifies the factors that regulate tick abundance is critical for predicting and managing human disease risk. Ticks are susceptible to high temperatures and low humidity at ground level, where they spend 95% of their lives. Spongy moth outbreaks occur roughly every ten years, can extend over large regions, and at high abundance can strip millions of (particularly oak) trees of their leaves, affecting conditions on the forest floor by removing shade, increasing temperatures, and decreasing humidity. This project is designed to ask whether defoliation by spongy moths causes changes in ground conditions that decrease survival and therefore population size of blacklegged ticks. The proposed research will evaluate the influence of humidity and temperature on tick survival and population growth at locations experiencing a range of spongy moth defoliation. The project will allow researchers to predict the impacts of current and future spongy moth outbreaks on risk of tick-borne diseases in nearby communities, facilitating interventions to protect public health. Post-baccalaureate Project Assistants will receive immersive training experiences that provide excellent preparation for research careers. The research involves the experimental deployment of all six stages in the life cycle of the blacklegged tick (i.e. engorged and unfed larvae, nymphs, and adults), in heavily defoliated, lightly defoliated, and experimentally shaded locations on each of six forest plots on the grounds of the Cary Institute of Ecosystem Studies. Known numbers of ticks will be placed in small soil-core enclosures and then enclosures will be removed at regular intervals to quantify mortality. Deploying all stages together with temperature and humidity data loggers inside soil-core enclosures, will allow the investigators to model the hazard of tick mortality as a function of abiotic conditions. Hazard of mortality for each life stage will then be integrated across life stages and abiotic conditions to inform a tick population matrix model and forecast tick-borne disease risk. Because other forest pests, disturbances, and climate change can have similar effects on conditions on the forest floor, the research will lead to a general understanding of what controls tick populations. 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.