Bd eliminated from Mallorcan ponds

***Fresh off the press*** Today heralds a good day for amphibians! Bosch et al have just reported in Biology Letters their success in eliminating the chytrid fungus Batrachochytrium dendrobatidis (Bd) from wild populations of Alytes muletensis in Mallorca ( The study presents a rapid response strategy driven by the decline of the IUCN red-listed Mallorcan midwife toad; the single amphibian host for Bd on the island. The study took place over five years and is based upon five permanent ponds at two different sites in Mallorca where infection with Bd had previously been reported. The successful approach involved draining the ponds, spraying the surrounding environment with disinfectant, treating tadpoles and terrestrial A.muletensis with antifungals and returning them to their original ponds once refilled by autumn rains. Returned animals were then monitored and remained free from infection in the two following years at four of the five sites.

This study is exciting in that it is the first of its kind to successfully eliminate Bd from wild populations in vivo. It comes at a time when amphibian species are declining at an alarming rate, with over 200 species reported as extinct due to chytridiomycosis and many more threatened with extinction. Existing strategies for mitigation involve maintaining disease-free captive-bred colonies and enhanced biosecurity, and strategies in development include host application of probiotics and environmental application of anti-Bd chemicals; however attempts at immunisation have thus far been unsuccessful. Whilst environmental use of Virkon S may be controversial and its impact on microbial biodiversity needs to be further assessed, it is currently one of only a few chemicals with antifungal properties against Bd. As yet, no one has found another way of effectively mitigating Bd in the wild, so this represents a huge step forward in the fight against chytridiomycosis. As this disease pushes more amphibian species nearer the brink of extinction we need to act fast and this study presents a much-needed rapid, inexpensive, straightforward and scalable way to combat infection as soon as it is discovered.

Adult Mallorcan Midwife Toad (Alytes muletensi)

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