Associação de inseticida sintético e Beauveria bassiana no controle da Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) na cultura do milho segunda safra

Abstract

Spodoptera frugiperda is one of the main pests of the maize crop, causing damage from the initial phase to senescence. The most widwly used management method uses insecticides that, in addition possibility of causing damage to the environment and human health, can also select resistant individuals. The use of biopesticides has been widwly studied for production in a more sustainable way and for reducing cases of resistance. Thus, this study aimed to evaluate the efficiency of the fungus Beauveria bassiana – commercial product Boveril®, isolated and associated with an insecticide Lannate®, in the control of S. frugiperda. The experiment was conducted in the field, in a completely randomized design, with 4 replications and 9 treatments: T1 (Control), T2 (Boveril® in half dose), T3 (Boveril® in full dose), T4 (Lannate® in full dose), T5 (Lannate® in half dose), T6 (Lannate® in half dose + Boveril® in half dose), T7 (Lannate® in full dose + Boveril®

in half dose), T8 (Lannate®

in half dose + Boveril®

in full dose), T9 (Lannate® in full dose + Boveril® in full dose).The conventional corn hybrid P3898 without technology to control weeds and caterpillars was used, planting was carried out in the second crop. The number of plants attacked in the treatments was evaluated at 17,24,21,38 and 45 days after crop emergence, to determine the application of the treatment, a control level of 10% of attacked plants was established after the senescence of the plant. Crop phytotechnical parameters were evaluated: number of grain rows, number of grains per row, ear size and weight of a thousand grains. The data obtained were submitted to analysis of variance with a confidence level of 95% and the Scott-Knott grouping of means test with a probability level of 5%. It was found that the treatment with Lannate®, in half dose, provided the best management of S. frugiperda, requiring less application and there was no synergistic effect between the fungus B. bassiana and the insecticide Lannate®, regardless of the dose used.