Dynamics of Chytrid Fungus (Batrachochytrium Dendrobatidis) Infection in Amphibians in the Rincon Mountains and Tucson, Arizona

Abstract

The chytrid fungus Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian declines around the world, including the southwestern United States. I studied patterns of Bd infection in Hyla arenicolor, Rana catesbeiana, and R. yavapaiensis in the Rincon Mountains and Tucson Basin in Arizona. Bd prevalence and infection intensity were location dependent in all species and R. yavapaiensis may be a reservoir of Bd for H. arenicolor, where they co-occurred. Treatment of a backyard population of R. yavapaiensis with itraconazole did not reduce winter frog mortality due to Bd. The lethal Bd infection threshold of this population was between 59,847 and 4,237,330 zoospores. Zoospore loads from swabs of freshly dead frogs did not differ significantly from those taken from those same frogs following freezing and thawing. Thus, important information regarding infection intensity and probable cause of death can be gathered from frogs collected by others and frozen until convenient to process.