A PROCESS MODEL FOR EASTERN BLACKHEADED BUDWORM (LEPIDOPTERA: TORTRICIDAE)

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Abstract
A theory for the population behavior of the eastern blackheaded budworm is presented. The qualitative properties and key processes of the system are identified and a description of the theory as a simulation model is given. Two domains of stability exist for the insect; one is caused by bird predation, the second by the effects of food limitation. The model predicts that the budworm’s cyclical population fluctuations are produced by the disappearance and reappearance of these stable domains and consequent movement of densities to new levels. Parasitism is identified as the principal mechanism causing this behavior. A qualitative comparison of model behavior with historical behavior is made and a critical field experiment to test the validity of the theory is proposed. Finally it is suggested that the population behavior of many forest defoliators may be explained using this theory.