Glyphosate-based herbicides reduce the activity and reproduction of earthworms and lead to increased soil nutrient concentrations

Abstract

Herbicide use is increasing worldwide both in agriculture and private gardens. However, our knowledge of potential side-effects on non-target soil organisms, even on such eminent ones as earthworms, is still very scarce. In a greenhouse experiment, we assessed the impact of the most widely used glyphosate-based herbicide Roundup on two earthworm species with different feeding strategies. We demonstrate, that the surface casting activity of vertically burrowing earthworms (Lumbricus terrestris) almost ceased three weeks after herbicide application, while the activity of soil dwelling earthworms (Aporrectodea caliginosa) was not affected. Reproduction of the soil dwellers was reduced by 56% within three months after herbicide application. Herbicide application led to increased soil concentrations of nitrate by 1592% and phosphate by 127%, pointing to potential risks for nutrient leaching into streams, lakes, or groundwater aquifers. These sizeable herbicide-induced impacts on agroecosystems are particularly worrisome because these herbicides have been globally used for decades.

Glyphosate and aminomethylphosphonic acid chronic risk assessment for soil biota

“…Although plant material treated with glyphosate at typical field application rates dies over a period of approximately 14 d to 21 d, depending on environmental conditions, plant growth stage, and species, sublethal effects such as withering can be observed at earlier time points because photosynthesis is affected via the shikimic acid pathway. Analogously, GauppBerghausen et al [29] tested 2 garden formulations on potted plants in soil mesocosms, at rates of 3.7 kg a.e./ha and 5.2 kg a.e./ha; but in the absence of a positive control with known toxicity to earthworms and without essential negative control treatments, plants were excluded for the effect of glyphosate and earthworms were excluded for the effect on soil nutrients; therefore, these results do not allow any conclusions on the toxicity of glyphosate to earthworms. The effects observed could be linked directly to the deterioration of the food source, which is constituted by the live plant material, and its degradation leading to increased free plant nutrient content in the soil, such as nitrate.…”

Re-registration Challenges of Glyphosate in the European Union

“…Formulated glyphosate-based herbicides, Touchdown R and Roundup R caused neurotoxicity (McVey et al, 2016) as well as locomotion and fertility inhibition (García-Espiñeira et al, 2018) on the nematode Caenorhabditis elegans. Following the results of the late Andrés Carrasco and his research group (Paganelli et al, 2010;Carrasco, 2013), recent findings in environmental toxicology of glyphosate and its formulated products include its revealed toxicity on amphibian species (Mann et al, 2009;Relyea and Jones, 2009;Meza-Joya et al, 2013;Wagner et al, 2013;Henao Muñoz et al, 2015;Baier et al, 2016a,b), on mollusks (Conners and Black, 2004) and on earthworms (Zaller et al, 2014;Gaupp-Berghausen et al, 2015). It affected hemocyte parameters and acetylcholinesterase (AChE) activity, but not antioxidant enzyme activities in mussel Mytilus galloprovincialis (Matozzo et al, 2018) with disruption of key biological processes including energy metabolism, Ca 2+ homeostasis and endoplasmic reticulum stress response, as well as cell signaling identified by transcriptome analysis (Milan et al, 2018).…”

Earthworms are little affected by reduced soil tillage methods in vineyards

“…6: 257-263 doi: 10.17221/160/2017-PSE earthworm species assemblages (Roger-Estrade et al 2010, van Capelle et al 2012. A possible detrimental effect of pesticides on earthworms (Gaupp-Berghausen et al 2015) as the paramount factor can be excluded as the same pesticides were applied for all tillage treatments. The current finding that abundances of epi-anecic earthworms were little influenced by tillage are in contrast to findings that epigeics were particularly sensitive to tillage (Paoletti et al 1998).…”