First Detection of Thiamethoxam in a Free-Ranging Insectivorous Bird After its Agricultural Use Ban in Spain

Neonicotinoids are insecticides used worldwide in phytosanitary and biocidal products and veterinary pharmaceuticals. Recently, some restrictions and bans have been imposed due to their adverse effects on nontarget invertebrates, including pollinators. Although they may have direct and indirect effects on wild vertebrates, few studies have assessed exposure to these compounds in wild birds, so our knowledge remains limited. In the present pilot study we have assessed the prevalence of seven neonicotinoid insecticides and some of their metabolites in whole blood samples from 19 European roller (Coracias garrulus) nestlings and five adult common kestrels (Falco tinnunculus) in an area treated with neonicotinoids to control the palm weevil (Rynchophorus ferrugineus) in southeastern Spain. One European roller nestling born in a palm tree was positive for thiamethoxam, with a concentration of 2.26 ng mL^-1, but no residues of neonicotinoids or their metabolites were found in adult common kestrels. Future studies are needed to elucidate potential exposure to neonicotinoids at different times of the year. To our knowledge, this is the first report of the presence of thiamethoxam residues in whole blood of a wild bird species after its ban in Spain. Environ Toxicol Chem 2024;43:1836-1843. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.