Interactions among gypsy moths, white-footed mice, and acorns

Low-density populations of gypsy moth, Lymantria ia dispar, were studied over a 10-yr period in Massachusetts. Increases in gypsy moth density were associated with declines in density of the white-fooled mouse, Peromyscus leucopus, a principal predator. Furthermore, changes in density of P. leucopus populations were positively correlated with the density of acorn crops, a dominant winter food sourer for these mice. To demonstrate these effects we used a novel bootstrap regression method that adjusts for spatial and temporal autocorrelation in the time series data. The findings are compatible with a dual equilibrium model of gypsy moth population dynamics, in which low densities are regulated by mice and high densities are regulated by other factors, notably a virus disease.