ORIGINAL ABSTRACT

Weeds growing in crops contribute to the maintenance of soil biodiversity; for example, they are a source of organic matter and nutrients for soil invertebrates. However, little is known about the impact of glyphosate-contaminated weeds on the behavior and survival of earthworms. The objective of this study was to evaluate the behavior and survival of the earthworm Eisenia andrei upon exposure to glyphosate-contaminated weed compost. The study employed standardized avoidance and acute tests to assess the repellency and mortality of E. andrei earthworms at four doses of the commercial herbicide (Faena Fuerte® 360): 0, 259, 398 and 437 mg/kg/ha. The avoidance essay results indicated that earthworms with similar biomass did not avoid glyphosate-contaminated weed composts, with avoidance rates < 80%. Furthermore, the acute test showed that commercial dose of glyphosate was not associated with growth and mortality. Consequently, it was concluded that weed composts with glyphosate not exert a sublethal and lethal toxic effect on E. andrei. It is recommended that future studies focus on the microbiota associated with native endogenous earthworms in the decomposition of the weed and the degradation of the herbicide.