Analysis of feces from red-legged partridges experimentally exposed to triazole fungicides is revealed as a non-invasive method to monitor farmland bird exposure to triazole fungicides
Agricultural intensification and the use of pesticides have been recognized as the main threats to the conservation of birds that live in agricultural environments. A widespread practice is the treatment of sown seeds with insecticides and fingicides to avoid the need to spray the fields during their initial stages. However, this practice poses a risk to granivorous birds that may consume these treated seeds, especially because sown seeds constitute a considerable part of the birds' diet during autumn and winter due to the scarcity of natural food items in these periods.
Triazole fungicides are the most widely used pesticides for seed treatment, with tebuconazole being the most widely used in Spain. In previous studies carried out at the Instituto de Investigación de Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM) it has been shown that the ingestion of cereal sown seeds treated with these compounds can cause chronic toxic effects on reproduction in red-legged partridges and, therefore, prolonged exposure could compromise the viability of their populations.
Thanks to the Agroperdiz and REGRESEEDS projects developed by the Research Group in Wildlife Toxicology of the IREC, an experiment has been carried out to develop a non-invasive method to monitor the exposure of wild birds to three triazole fungicides widely used for sown seed treatments, using the red-legged partridge (Alectoris rufa) as a study model.
For this, red-legged partridges were fed experimentally with seeds treated with commercial doses of three triazole fungicides: tebuconazole, prothioconazole, and flutriafol. Subsequently, the detectability of these compounds and their metabolites was evaluated in two types of feces samples (rectum and blind), both at the end of the exposure and 7 days later. On the other hand, scientists looked for the presence of fungicides in the digestive content of some of the exposed partridges to find out how the concentrations found there are related to those present in the feces and thus be able to estimate indirect oral exposure from feces analysis. Finally, to determine the applicability of the non-invasive method in a real scenario, fecal samples of red-legged partridge collected in the field during the sowing season were analyzed..
Collection of feces samples of wild red-legged partridges in the field to monitor exposure to triazole fungicides.
The results of the study revealed that fecal analysis is a good method to monitor recent exposure to triazoles in birds.. Residues were only detected in feces collected immediately after exposure to the pesticide. Prothioconazole was well detected in feces, both from the cecum (93,3%) and from the rectum (73,3%), while tebuconazole appeared mainly in rectal feces (80%). Flutriafol was the least detected fungicide in its original form (28,4% of rectal faeces, 40% of cecum faeces), which is related to the ability of birds to metabolize it to a greater extent than the other two compounds, which proof that the red-legged partridges exposed to flutriafol were those in which the detection of the 1,2,4-triazole metabolite was higher (60% of rectal feces).
On the other hand, 18,6% of the wild partridge samples had detectable levels of tebuconazole. By applying the relationship between the detection of this fungicide in feces and digestive content observed during the experiment, the analysis of feces from wild partridges led to the estimate that 22,3% of the animals would have recently ingested seeds treated with tebuconazole. Likewise, using the results obtained experimentally, an average concentration of 246 ng/g in gizzards of wild partridges was estimated, being consistent with the concentrations found in previous studies in the gizzards of hunted partridges from the same region.
Graphic abstract of the research work.
This study highlights the importance of developing research to determine the effectiveness of non-invasive methods to monitor exposure to pesticides in wildlife, since there may be factors that can influence the detection of these compounds, such as bioavailability and metabolism of pesticides on exposed organisms. The wide use of triazoles for the treatment of sowing seeds and the recognized risks that this agricultural practice poses for granivorous birds support the need to develop monitoring tools to be able to carry out a real risk assessment of these products in the environment once they have been approved for commercial use.
The scientific publication of this research is available at:
- Fernández-Vizcaíno, E., Mougeot, F., Mateo, R., Camarero, PR, Alcaide, V., Ortiz-Santaliestra, ME 2023. A non-invasive method to monitor farmland bird exposure to triazole fungicides. Chemosphere 325, 138316.