Behavior and survival of earthworm (Eisenia andrei) to exposure to glyphosate-contaminated weed compost

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 a 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 (l/ha): Control = 0, Low = 2, Medium = 4, and High = 6. The avoidance essay results indicated that earthworms with similar biomass did not avoid glyphosate-contaminated weed composts, with avoidance rates < 80%. However, the acute test revealed that increasing the herbicide dose led to a reduction in earthworm growth and mortality. Consequently, it was concluded that weed composts with glyphosate exerted a toxic effect on the survival of E. andrei. It is recommended that future studies focus on the microbiota associated with E. andrei in the decomposition of the weed and the degradation of the herbicide.