During the 1980's, the gypsy moth, an invasive Eurasian species, caused severe forest defoliation in New York State. While investigating how forests responded to defoliation stress, Institute ecologists discovered that white-footed mouse populations played a large role in regulating the moths. Key predators on gypsy moth pupae, research showed that moth populations declined when mice were abundant. More interestingly, scientists discovered a connection among acorn production, mouse population size and the number of blacklegged ticks infected with Borrelia burgdorferi, the bacterium that causes Lyme disease.

While gypsy moth populations have declined over the past decade, the incidence of Lyme disease infections has risen dramatically. The U.S. Centers for Disease Control ranks Dutchess County, where the Institute is located, as having the second highest Lyme disease infection rate in the nation. Since 1991, in response to the unique opportunities posed by the Institute's location and past research on white-footed mice, Institute Ecologist Dr. Richard S. Ostfeld has been investigating the ecology of Lyme disease.

The research being conducted by Dr. Ostfeld and colleagues departs from the tradition of studying vertebrates from a population perspective and sheds light on the system-level consequences of animal fluctuations. By melding ecology, epidemiology, and community modeling, they are investigating the players involved in Lyme disease and how they vary in space and time. While mice are the primary disease carriers, other vertebrates, such as birds and squirrels and lizards, also play crucial roles.

Thus far, their ecosystem approach has demonstrated that Lyme disease risk decreases when vertebrate communities contain many species (high biodiversity) and increases when the habitat is highly fragmented with lower diversity. Through identifying the conditions that regulate Lyme disease risk, their findings will help determine how ecosystems can be best managed for human health. Given that at least 60% of all infectious diseases of humans originate with non-human animals (for example, HIV/AIDS, SARS, avian influenza, hantavirus disease, monkeypox, Ebola), understanding how disease agents move from mammals and birds to humans is essential. Changing ecological conditions play a key role in increasing disease risk.