Using glyphosate puts worms at "risk of local extinction" – study

Using glyphosate herbicide can wipe out local earthworm populations, a new study (below) shows. Even at exposures under the regular dose for perennial weeds, the earthworm population showed negative growth rates, meaning there were not enough young worms to replace the old ones as they died out. This means the local worm population could rapidly go extinct.

Given the irreplaceable work that earthworms do to keep the soil healthy, and the negative effects of glyphosate herbicide on beneficial soil microorganisms, it's no surprise that Roundup Ready crop cultivation is associated by some farmers with poor soil quality.

Glyphosate Sublethal Effects on the Population Dynamics of the Earthworm
Eisenia fetida (Savigny, 1826)

Marina Santadino, Carlos Coviella, Fernando Momo
Water, Air, & Soil Pollution
November 2014, 225:2207


Pesticides’ sublethal effects are not regularly taken into account when assessing agrochemical’s toxicity. With the objective of detecting chronic, sublethal effects of the widely used herbicide glyphosate, an experiment was performed using the earthworm Eisenia fetida as model organism. Earthworm adults were randomly assigned to three glyphosate treatments: control (no glyphosate), regular dose for perennial weeds, and double dose. Six E. fetida individuals were placed in each pot. Two random pots were taken weekly from each treatment and the number of adults, individual weight, number of cocoons, and presence and number of young earthworms were recorded. A matrix analysis was performed with the data. The matrix population model built showed that while the control population had a positive growth rate, both glyphosate treatments showed negative growth rates. The results suggest that under these sublethal effects, non-target populations are at risk of local extinction, underscoring the importance of th[ese] type of studies in agrochemical environmental risk assessment.