Widespread triazole pesticide use affects infection dynamics of a global amphibian pathogen

• Published in: Ecology letters 2023-02, Vol.26 (2), p.313-322
• Main Authors: Barbi, Andrea, Goessens, Tess, Strubbe, Diederik, Deknock, Arne, Van Leeuwenberg, Robby, De Troyer, Niels, Verbrugghe, Elin, Greener, Mark, De Baere, Siegrid, Lens, Luc, Goethals, Peter, Martel, An, Croubels, Siska, Pasmans, Frank
• Format: Article
• Language: English
• Subjects: Agricultural land; Amphibians; Amphibians - microbiology; Animals; Anthropogenic factors; Batrachochytrium; Bioaccumulation; Biodiversity; Breeding seasons; chytrid; Chytridiomycosis; Chytridiomycota; Epoxiconazole; Fungal diseases; Fungi; Fungicides; Human influences; infection dynamics; Infections; Mass extinctions; mitigation; Mycoses - epidemiology; Mycoses - veterinary; Pesticides; Plant Breeding; Ponds; Triazoles; Triazoles - pharmacology; Water circulation; Water column
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/ele.14154

The sixth mass extinction is a consequence of complex interplay between multiple stressors with negative impact on biodiversity. We here examine the interaction between two globally widespread anthropogenic drivers of amphibian declines: the fungal disease chytridiomycosis and antifungal use in agriculture. Field monitoring of 26 amphibian ponds in an agricultural landscape shows widespread occurrence of triazole fungicides in the water column throughout the amphibian breeding season, together with a negative correlation between early season application of epoxiconazole and the prevalence of chytrid infections in aquatic newts. While triazole concentrations in the ponds remained below those that inhibit growth of Batrachochytrium dendrobatidis, they bioaccumulated in the newts' skin up to tenfold, resulting in cutaneous growth‐suppressing concentrations. As such, a concentration of epoxiconazole, 10 times below that needed to inhibit fungal growth, prevented chytrid infection in anuran tadpoles. The widespread presence of triazoles may thus alter chytrid dynamics in agricultural landscapes. By combining an extensive field dataset with experimental trials, we examined the interaction between two globally widespread anthropogenic drivers of amphibian declines: the fungal disease chytridiomycosis and antifungal use in agriculture. We estimated the impact of triazoles use on B. dendrobatidis infection dynamics by determining its potential (1) to bioaccumulate in amphibians, (2) to effectively limit B. dendrobatidis growth and (3) to affect B. dendrobatidis infection dynamics in tadpoles. We showed that exposure to relevant field concentrations of epoxiconazole that are well below concentrations that limit fungal growth accumulate in amphibian skin and prevented infection with B. dendrobatidis, thus altering chytrid dynamics in agricultural landscapes.