Integrating adverse effects of triazole fungicides on reproduction and physiology of farmland birds

Abstract

The extensive use of pesticides has been recognized as one of the major factors negatively impacting birds in agricultural habitats. One of the pesticide groups most used worldwide are triazole fungicides due to their effectiveness in controlling phytopathogenic fungi in cereals, vineyards and orchards. In the last decades, different experimental studies have reported important negative effects on the health and fitness of birds after exposure to triazoles. Birds can be exposed throughout the year through different routes, including oral uptake, dermal contact with treated surfaces and inhalation by overspray. Yet, the ingestion of treated or sprayed material is the principal route. The most alarming effect of triazoles, which can even occur several months after cessation of the exposure, is the decreasing reproductive outputs of birds, including delay in the onset of laying dates, reduced clutch size and hatching rate, and increased mortality of chicks. In order to synthesize the data and knowledge about the toxic effects of triazoles at different levels of biological organization, here we propose an dverse outcome pathway (AOP) on the mechanisms by which triazoles can affect avian reproduction and physiology. The reported effects highlight that the current risk assessment needs some improvements to avoid undesired effects on birds, especially long‐term effects that can influence stability and viability of avian populations from agricultural habitats.