Further impacts on biodiversity (plants, birds, ecosystems)
As a broad-spectrum herbicide, glyphosate kills all plants, without distinguishing between unwanted weeds and beneficial plants (e.g. herbs, shrubs and trees, bearing flowers or not). No other herbicide is so non-selective. The effect caused by exposure to glyphosate on plants is not limited only to the treated area but also extends to neighbouring areas. Scientific findings show that in green areas close to fields treated with glyphosate products, there is a significant decrease in plant life, including flowers and wild plants.
This is of concern because the decline in plant species can have far-reaching consequences, as plants are an essential component of biodiversity. They provide habitat and food for a wide range of terrestrial species, including insects, which are natural predators, amphibians, pollinators, and birds. Therefore, the decline in plant species due to glyphosate exposure can have a cascading effect on ecosystems, leading to biodiversity loss.
Birds are exposed to glyphosate via direct contact in their surrounding environment or through glyphosate-contaminated food. This herbicide can alter gut bacteria communities and therefore the intestinal microbiome. Glyphosate in food can also affect egg production and fertility/‘hatchability’. Exposure of birds to glyphosate via maternal transfer has been shown to cause foetal and embryonic malformations, and alterations of the paternal sperm, which can lead to effects on subsequent generations (epigenetic).
The use of glyphosate has been linked to the decline of monarch butterfly populations, in proximity to fields with glyphosate-resistant GM crops. These butterflies rely on milkweeds as their sole food source during their larval stage. However, glyphosate is very toxic to milkweed plants, and therefore their destruction due to the widespread use of glyphosate-based products in North America has been identified as a significant cause of monarch butterfly population decline.
PAN EUROPE ( 2017): Summary on the toxicity of Glyphosate
Friends of the Earth (2021) : Monarch Butterfly Endangered (glyphosate)
Mc Gill University (2020) : Widely used weed killer harming biodiversity
Heinrich-Böll-Stiftung (2022) : Biodiversity: extinction in full swing.
Heinrich-Böll-Stiftung (2022) : Soils: impact on the invisible ecosystem.
Friends of the Earth Germany (GER) (2021) : Phasing out glyphosate in favor of biodiversity
Scientific research papers
Thies, Carsten, et al., “The Relationship between Agricultural Intensification and Biological Control: Experimental Tests across Europe.”, (Ecological Applications, vol. 21, no. 6, 2011).
Shehata AA et al., “The effect of glyphosate on potential pathogens and beneficial members of poultry microbiota in vitro”, (Curr Microbiol. 2013 Apr;66(4)).
Belsky, J., & Joshi, N. K., “Assessing Role of Major Drivers in Recent Decline of Monarch Butterfly Population in North America”, (Frontiers in Environmental Science, 6, 2018).
Ruuskanen, S. et al., “Effects of parental exposure to glyphosate-based herbicides on embryonic development and oxidative status: a long-term experiment in a bird model”, (Scientific Reports, 10., 2020).
Sánchez-Bayo, F., “Indirect Effect of Pesticides on Insects and Other Arthropods”, (Toxics, 9(8), 2021).
Foldager, L. et al., “Impact of feed glyphosate residues on broiler breeder egg production and egg hatchability”, (Scientific Reports, 11, 2021).
Estienne, A. et al., “Chronic dietary exposure to a glyphosate-based herbicide results in reversible increase early embryo mortality in chicken”, (Ecotoxicology and Environmental Safety, 241, 2022).