Avalição toxicológica da linhagem bacteriana 358.1 isolada do petróleo sobre Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae).

Abstract

Corn is one of the most produced and important crops in the world, utilized for human and animal feeding. Brazil is one of the top producers of this grain, being the third biggest producer worldwide. Despite the great production, the productivity is compromised due to the activity of insect pest. Because of this challenge, the continuous use of insecticides is done aiming to minimize lost in the crops. However, it causes major environmental impact and it is also contaminating rural workers. One of the viable and promising strategies to the pest suppression has been the pest integrated management (PIM), which is based on the use of isolated or consortium of pest controlling techniques, the biological control being one of the most sustainable tools in an ecological perspective. Therefore, the present study had the goal of evaluating the toxicity of the 358.1 bacterium strain isolated from the oil and supernatant of the cell culture under control of caterpillars from 2nd and 3rd instars of S. frugiperda, comparing the death rates and effects on their development, and also comparing with commercial chemical insecticides. The experiment consisted in two stages; the first assay was done with 3rd instar caterpillar with three different dilutions from the 358.1 strain, supernatant of the cell culture, saline solution as negative control, and fenpropatrina insecticide as positive control. On the second assay, 3rd and 2nd instars caterpillars were used, the cell culture from the 358.1 strain on its total concentration (4 x 108 UFC/mL), supernatant of the cell culture, distilled water as negative control and flubendiamida, a commercialized product, as the positive control. The experiments with the 358.1 strain, supernatant of the cell culture and the tested chemical products didn’t show a significant death rate for S. frugiperda, however, the 358.1 strain and supernatant of the cell culture resulted in an increase in the larval phase duration and on morphophysiological disturbs on the insect, resulting yet in the emergence of adults with atrophied wings, thus being promising to the realization of new tests.