Glyphosate Impact on Arthropods Associated to Roundup Ready and Conventional Soybean (Glycine max L.)

ABSTRACT: This study aims to evaluate the impact of glyphosate-resistant soybean and its management with glyphosate on the canopy arthropod community. We study the direct impact of the insertion of the resistance gene and the indirect impact of management practices, specifically herbicide application. To do this, we use the following treatments: non-GM and GM soybean with mechanical weed control and GM soybean with one and three applications of glyphosate. Arthropods in the crop canopy were sampled over time in all treatments. The incorporation of the glyphosate resistance gene did not affect the richness and abundance of arthropods in the plant canopy. Glyphosate application reduced the richness of predators and chewing and sucking phytophagous arthropods in treatments with three herbicide applications. In the second season, total arthropod density was the lowest in transgenic soybean with three glyphosate applications. The density of Cerotoma arcuatus, a chewing phytophagous arthropod, followed similar trends, while both glyphosate treatments (one or three applications) reduced the densities of the predator Solenopsis sp. and the detritivore Hypogastrura sp. Meanwhile, the densities of the sucking phytophagous arthropods Bemisia tabaci, Caliothrips brasiliensis, and Tetranychus sp. were the highest in transgenic soybean with three glyphosate applications.