Models of mast seeding and its ecological effects on gypsy moth populations and Lyme disease risk

Date of Completion

January 2000


Biology, Ecology|Agriculture, Forestry and Wildlife




Mast seeding, the intermittent production of large seed crops, can drive large fluctuations in abundance of granivores, and can have indirect effects that extend to a surprising array of species and ecological processes. Acorn masting has been hypothesized to indirectly control the initiation of gypsy moth outbreaks and the risk of Lyme disease, mediated by the direct effect of acorns on the abundance of white-footed mice. Through a combination of field experimentation, curve fitting to observational data, and modification of existing theory, I constructed mathematical models describing the masting phenomenon, and capturing its direct and indirect effects on gypsy moth populations and Lyme disease risk. I demonstrated synchronous masting by a suite of taxonomically diverse plants in New Zealand and used models to investigate the role of temperature as a synchronizing cue. I experimentally determined the type of functional response of white-footed mice to gypsy moths, and used monitoring data to parameterize a functional response model incorporating mouse space use. I then used this model, in conjunction with models simulating acorn masting the numerical response of mice, to explore the effect of acorns and mice on gypsy moth population dynamics. Finally, I modified epidemiological models to investigate the role of time-decaying reservoir competence and demographic turnover, of hosts like white-footed mice, on the ecology of Lyme disease. ^