"EFFICIENCY OF Bacillus thuringiensis IN CONTROLLING THE CORN FALL ARMYWORM IN LAB CONDITIONS"

Resumo

The region of Triângulo Mineiro, in the state of Minas Gerais, has one of the highest corn productivity in Brazil. However, such productivity is significantly affected by the damage of the fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae), one of the most important pests in corn fields. Due to the necessity of a well-established control, the purpose of this study was to evaluate the efficacy of some insecticides commonly used by growers in this region, both biological and chemical. Under controlled laboratory conditions, we assessed mortality of second-instar S. frugiperda larvae on artificial diet treated with insecticides using manufacturer-recommended dosages. Three chemical insecticides, one bioinsecticide and one control (distilled water + Tween® 0.5 %) were tested. The larval mortality was evaluated 12, 24, 48, 72, 96 and 120 hours after the treatment of single application. It was possible to conclude that the bioinsecticide had the same efficiency as all the insecticides tested, with all treatments causing around 100% mortality of S. frugiperda larvae. The corrected mortality (CM) was calculated though the Schneider-Orelli formula and, it was possible to conclude that all the insecticides tested were efficient controlling S. frugiperda larvae, with calculated CM higher than 92 %, with no difference between the insecticide treatments. These results show that the products used by the corn growers from the region of Triângulo Mineiro, in the state of Minas Gerais, are efficient in controlling S. frugiperda under controlled conditions. Moreover, the results of Bt-bioinsecticide show that it is as efficient as the chemical insecticides, and can be used for controlling this pest in corn fields after regulation.