Perdas de produtividade e sistemas de tomada de decisão para pragas em cultivos de soja

Abstract

In view of the need to improve the control of phytosanitary problems resulting from the attack of insect pests and diseases in the cultivation of soybean to increase the productivity of this oilseed, it is necessary to understand the dynamics of the pests by identifying the critical periods of the attack on the crop and to quantify the yield losses for the adoption of management strategies. Thus, this thesis was divided into two chapters. In the first chapter, the components, and factors of yield losses in transgenic Bt-RR soybeans were studied using the life table. In the second, a feasible sampling plan for control decision making for the Anticarsia gemmatalis (Hübner), Chrysodeixis includens (Walker), Helicoverpa armigera (Hübner), Spodoptera cosmioides (Walker), Spodoptera eridania (Stoll) e Spodoptera frugiperda (JE Smith) in soybean it was determined. This work was realized out in commercial soybean crops, for two years. For the study of the critical component and the key loss factors, plant mortality and pod and grain losses were monitored. To determine the sampling plan, the techniques used in sampling the pest were evaluated. The number of samples, the admitted error, the time, and the cost of sampling were also determined. Losses in soybean crop yields were due to plant mortality, aborted of flowers and pods and damage to grains. Pods and grains are considered as critical components of yield loss. The key loss factor in soybean crops was insects. The sampling plan with beating the plants in a plastic tray has a cost and execution time like the plan currently used with the beating cloth. The sampling plan was composed of 61 samples and has the advantage of making precise and representative determinations of the attack intensity of the caterpillars in soybean crops.