Economic threshold for a pathogenic disease: The case of Varroasis in bees

A long-run economic decision model is used to determine optimal treatment regimes for control of Varroasis in honey bees. Decision treatments are based on timing and duration of chemicals as used in laboratories and small scale field trials. The model was applied to conditions prevailing in Israel. Under these conditions the optimal decision rule was sensitive mainly to the rate of interest, the size of the apiary, the initial population of Varroa, and especially the length of the time horizon. The model can be modified very easily to different economic and biological conditions.