Modelling the interaction of cotton and the cotton boll weevil. II. Boll weevil (Anthonomus grandis) in Brazil.
A population dynamics model of the field biology of the curculionid Anthonomus grandis under Brazilian conditions was linked to a model for cotton growth and development. An age-structured, distributed maturation times population dynamics model with attrition was used for both the plant and the curculionid. The models are demand driven and all aspects of the biology are controlled by the interplay of resource supply and demand. The model compared favourably with field data. Simulation analysis showed that insecticides are needed to control the pest as there are no effective biological control agents in Brazil. The model suggests that the use of an economic threshold based on the ratio of the rate of fruit point production to fruit damage can greatly reduce the number of applications required.