From plant to predator: glyphosate trophic transfer harms ladybird physiology and reproduction

With the increasing use of glyphosate, residues have been detected in many organisms, raising concerns about impacts on animal health and ecosystems. The present study addressed the biological question: How does glyphosate exposure, at environmentally relevant and higher concentrations, affect the survival, growth, reproduction, and carbohydrate metabolism of the ladybird Harmonia axyridis (Pallas), a key natural enemy of aphid pests? To simulate food chain contamination, aphids were fed glyphosate-sprayed broad bean seedlings and then fed to H. axyridis.

Glyphosate residues were found throughout the broad bean-aphid-ladybird system, with the highest levels in broad bean roots (85 mg/L) and adult ladybirds (74 mg/L). Exposure to glyphosate concentrations ≥ 50 mg/L affects the growth and development of H. axyridis, with higher concentrations having a considerable impact. Concentrations ≥ 100 mg/L significantly decreased oviposition and egg hatching rates. At the molecular level, glyphosate exposure caused down-regulation of the TRE1-1 gene during the fourth instar, pupa, and adult stages, along with decreased trehalase activity and increased trehalose content, indicating disrupted carbohydrate metabolism. Glucose and glycogen levels remained unaffected.

This combination of trophic transfer assays and molecular analyses clarifies glyphosate's detrimental effects on a key beneficial predator, emphasizing the importance of cautious herbicide management for preserving natural pest control services and maintaining ecological balance in agricultural ecosystems. This is a measure that can help mitigate the cascading risks of herbicide misuse to field-level biological pest suppression. © 2026 Society of Chemical Industry.