Computer simulation of population dynamics of the American dog tick (Acari: Ixodidae).

A comprehensive computer model was developed for simulation of the population dynamics of the American dog tick (ADT), Dermacentor variabilis Say, in North America. The model simulates the effects of major environmental variables, such as ambient temperature, saturation deficit, kind of habitat, and host density, on ADT population dynamics in ecosystems with small mammals as hosts for immature ticks and medium-sized mammals or domestic dogs as hosts for adult ticks. General validity of the model was established by comparisons between simulated and actual population densities for a series of years at locations in Virginia, Maryland, and Massachusetts using actual weekly weather data for each year as a model input. Using historical-average weather data for 11 locations within the known geographic range of ADT and 3 locations outside this range, the model produced acceptable values for initial population growth rate and generation time, as well as realistic equilibrium population densities and seasonal activity patterns. This model can be used as a framework for additional modeling efforts to simulate the transmission of Rocky Mountain spotted fever and to study various strategies for management of ADT populations.