Barbi et al. (2023) Widespread triazole pesticide use affects infection dynamics of a global amphibian pathogen. Ecology Letters
Ichthyosaura alpestris (c) Frank Pasmans
Fungicides are widely used pesticides to control fungal diseases in crops. Negative effects on the environment are well document and include toxicity and bioaccumulation. We have recently discovered that the extensive presence of triazole fungicides in amphibian breeding ponds within agricultural landscapes can influence the course of a disease that is a global driver of amphibian declines and is caused by the amphibian-killer fungus Batrachochytrium dendrobatidis (Bd).
While the fungicides are widespread in ponds of our study region, their concentrations are typically very low. However, accumulation up to tenfold within the amphibian skin resulted in concentrations that inhibit the growth of Bd. In our study ponds, this was reflected by reduced occurrence of Bd in newts. Also, this prevented infection of tadpoles after exposure to Bd. As such, contamination of amphibian breeding ponds with pesticides may reduce the impact of the disease on amphibian populations, which may in part explain the current lack of observed disease outbreaks in northwestern Europe.
Does this mean we should advocate the use of fungicides to control amphibian diseases? There is a strong societal tendency to limit the use of pesticides in agriculture for reasons of environmental and human health. The application of fungicides in natural environments may have a severe negative impact on the exposed ecosystem. Environmental application of fungicides may promote the emergence of acquired antifungal resistance in fungal pathogens, which compromises the treatment of humans. Only in specific cases and after thorough risk-assessment, the temporary and localized use of fungicides may be considered as part of a (currently very limited) arsenal of measures to curb further disease driven loss in amphibians. However, such interventions should not replace efforts for the development of long term and sustainable disease control.
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