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

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, this study´s objective was to evaluate the efficacy of some insecticides commonly used by growers in this region, both biological and chemical. The experiment was performed under controlled laboratory conditions (25 ± 2oC, 70 ± 10% RH, and a photoperiod of 12h), using artificial diet. A completely randomized design was used, in which one second instar S. frugiperda larvae and one 1cm 3 unity of artificial diet treated with one of the insecticides were put together in a plastic container (100 mL), in a total of five repetitions of ten insects, per treatment. Three chemical and one biological insecticides were tested, using the dosages recommended by the respective leaflets, and one control (distilled water + Tween® 0,5%). 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 all the insecticides tested were efficient, causing around 100% mortality of S. frugiperda caterpillars. 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 caterpillars, with calculated CM higher than 92%, with no difference between the insecticide treatments.