Glyphosate residues in soil can modify plant resistance to herbivores through changes in leaf quality.

Abstract

Glyphosate is the most widely used non-selective herbicide in the world. Glyphosate residues in soil can affect plant quality by modifying plant physiology, hormonal pathways and traits, with potential consequences for plants' interactions with herbivores.• We explored these indirect effects in the context of plant-herbivore interactions in a perennial, nitrogen-fixing herb. We quantified leaf herbivory for glyphosate-exposed and control plants grown in phosphorus-fertilized and non-fertilized soils, and assessed the impacts of glyphosate treatment on traits related to plant resistance against herbivores (leaf trichome density, leaf mass per area) and performance (aboveground biomass, root:shoot ratio, nodule number, nodule activity). Moreover, we conducted a laboratory feeding experiment to compare the palatability of leaves from glyphosateexposed and control plants to a generalist mollusc herbivore.• Herbivore damage and intensity in situ increased during the growing season regardless of glyphosate or phosphorus treatment. Glyphosate treatment reduced leaf trichome density but had no effect on the other plant traits considered. Herbivore damage was negatively associated with leaf trichome density. The feeding experiment revealed no difference in the feeding probability of mollusc herbivores between glyphosate-exposed and control plants. However, there was an interaction between glyphosate treatment and initial leaf area for leaf consumption by herbivores: leaf consumption increased with increasing leaf area in both groups, but at a lower rate for glyphosate-exposed plants than for control plants.• Our results show that glyphosate residues in soil have the potential to indirectly affect aboveground herbivores through changes in leaf quality, which may have mixed consequences for folivore damage.

Morphological, Histological, and Glyphosate Residue Analysis of Helianthus annuus L. Plants Treated with Glyphosate

“…The parent compound was introduced by Monsanto Corporation under the brand name 'Roundup' in 1974 [6][7][8]. Glyphosate is the most widely used herbicide in the world [9], which targets 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) and inhibits the biosynthesis of aromatic amino acids in Agriculture 2023, 13, 1014 2 of 15 the shikimate pathway [10][11][12]. In turn, glyphosate is a non-selective herbicide, an active ingredient without any available analogues in its mode of action category.…”

Herbicide residues in soil decrease microbe‐mediated plant protection

“…Glyphosate residues in soil have previously been found to modify plant resistance to aboveground herbivory via changes in leaf quality (Ramula et al . 2022).…”

“…Our field results demonstrate that the effects of GBH residue concentrations, which are similarly found across all European soils (Silva et al 2018), are not limited to reducing belowground microbe viability but may also negatively affect productivity of a plant's beneficial microbial symbiont growing in the aerial plant endosphere, leading to a decrease in plant protection against aphids. Glyphosate residues in soil have previously been found to modify plant resistance to aboveground herbivory via changes in leaf quality (Ramula et al 2022).…”

Recent advances in soil glyphosate contamination and removal

“…The rampant use of these substances has generated major negative impacts on the soil. It is considered the most widely used herbicide in the world, as well as being one of the most harmful to human health (Ramula et al, 2022).…”

“…It is considered the most widely used herbicide in the world, as well as being one of the most harmful to human health. This compound is used to control harmful or invasive weeds (aChen; Liu 2007;Ramula et al, 2022).…”