POPULATION-DYNAMICS OF A PARASITE AND HYPERPARASITE IN A CLOSED-SYSTEM - MODEL ANALYSIS AND PARAMETER-ESTIMATION

In this paper, we introduce and test models of the dynamics of a paras ite and hyperparasite in a closed system from which the parasite's hos t is excluded. The models are tested against data for the temporal dyn amics of a fungal plant parasite of lettuce, Sclerotinia minor, and a fungal hyperparasite, Sporidesmium sclerotivorum. The models are devel oped by treating the hyperparasite-parasite dynamics as a classical pr edator-prey system, but then expanding the prey component into a compa rtmental system of susceptible (uninfected) and infected parasites. Th e resulting hybrid model enables the separation of the dynamics of sus ceptible parasites, which are capable of causing disease, and infected parasites, which support reproduction of the hyperparasite. The influ ence of different functional and numerical responses are compared by a nalytical results and by parameter estimation.