Screening for Batrachochytrium dendrobatidis in New Zealand native frogs: 20 years on

A chytrid fungus (Batrachochytrium dendrobatidis; Bd) has been a cause of amphibian declines worldwide. Batrachochytrium dendrobatidis was first detected in New Zealand on an introduced frog species in 1999 and two years later was associated with morbidity in Leiopelma archeyi, one of the three native New Zealand frog species. In this study, we aimed to document the prevalence of Bd in native frog species in New Zealand from 2014–2021. Skin swabs were collected from six sites in New Zealand: Maud Island/Te Pākeka, Zealandia Ecosanctuary, Auckland Zoo, and University of Otago between 2019–2021, and Whareorino Forest and Pukeokahu between 2014–2020. Swabs were analysed using qPCR to detect Bd from skin swabs. A total of 324 frogs from the six sampling sites were screened for Bd presence. Four percent of the L. hamiltoni and eight percent of the L. archeyi were Bd-positive, and all L. hochstetteri were Bd-negative. The detection of Bd in Leiopelma species confirmed that Bd persists in New Zealand endemic frogs at a low prevalence and intensity.