SIMULATION OF MULTIPLE SPECIES PEST DAMAGE IN RICE USING CERES-RICE

Conventional approaches of using empirical equations for quantifying yield losses due to rice pests are limited in their scope and application since these equations are data-specific and insensitive to variable cropping and pest conditions. Recent developments in crop growth modelling provide a physiologically based approach to simulate pest damage and crop interactions. A generic approach to simulate the damage effects of single or multiple pests is presented using the CERES-rice crop growth model. Pest or damage levels from field scouting reports can be entered and damage is applied to appropriate physiological coupling points within the crop growth model including leaf area index, stand density, intercepted light, photosynthesis, assimilate amount and translocation rate, growth of different plant organs and leaf senescence. Equations and algorithms were developed to describe competition among multiple pests and to link the computed total damage to the corresponding variables of the crop model. A sensitivity analysis was conducted for various individual damage coupling points and for the damage effects of defoliators, weed competition, leaf blast and sheath blight disease. The general response of the model compared favorably with values reported in the literature. The model was also tested for sensitivity to multiple damage. Multiple pest damage usually had less-than-additive effects on yield loss. The approach provides a basis to explore dynamic pest and crop interactions in determining pest management strategies which minimize yield loss.