Female Preference and Adverse Developmental Effects of Glyphosate-Based Herbicides on Ecologically Relevant Traits in Japanese Quails

Controversial glyphosate-based herbicides (GBHs) are the most frequently used herbicides globally. An increasing number of studies have identified GBH residues in soil, water, and even human food that may expose nontarget organisms including wildlife, livestock, and humans to health risks. After a heated debate, the European Union allowed the use of GBHs to continue until 2022, after which their risks will be re-evaluated. Thus, decision makers urgently need scientific evidence on GBH residues and their possible effects on ecosystems. An important, yet neglected, aspect is to assess whether animals show preference or avoidance for GBH-contaminated food, as it can influence the likelihood of adverse health effects in wildlife. Here, using Japanese quails (Coturnix japonica) as our model, we show that females preferred GBH contaminated food compared to control food. In females, exposure to GBHs caused delayed plumage development, and GBH residues were present in eggs, muscles, and liver. These results indicate that female preference is not adaptive, potentially exposing nontarget animals to greater risk of adverse effects of GBHs in natural and agricultural environments. Our results on tissue residues suggest that further studies are needed to understand the risks of such residues in the food chain.