Biological control of beet armyworm, Spodoptera exigua, with baculoviruses in greenhouses : development of a comprehensive process-based model

We describe the development of a comprehensive process-based model simulating the epizootiology and agronomic efficacy of baculoviruses used for biological control of beet armyworm, Spodoptera exigua, in greenhouse chrysanthemum. The model is built to help understand, evaluate, and predict the effects of genetic modification, formulation, and application strategy of a baculovirus on its epizootiology and agronomic efficacy in a greenhouse cropping system. The model was constructed such that the impact of detailed aspects of the virus–host relationship, cropping system, spraying regime, and insect ecology on control could be evaluated. The resulting model is highly detailed, covers four spatial scales, from the leaf to the greenhouse, and addresses spatially explicit processes at the individual level and spatially averaged population processes. Submodels describe the crop production system and plant growth, the distribution and dispersal of insects within the crop canopy, spray deposition, uptake of virus, the probability of death and survival time of infected insects, and vertical and horizontal transmission. This paper describes the conceptual basis of the model and its parameterization by quantitative descriptions of model components. Model components are tested by comparison with dependent and independent experimental dat