Green and golden bell frogs are innately attracted to chytrid and can learn to avoid it

Batrachochytrium dendrobatidis (Bd) is a fungal pathogen known to cause chytridiomycosis in amphibians. The disease has been associated with the extinction of at least 90 species worldwide, including four Australian frog species. Although anti-parasitic behaviours are the first line of defence against infection, behavioural responses to Bd have been largely overlooked. We conducted a pilot study to test if L. aurea is capable of learning to avoid Bd after exposure to and subsequent recovery from infection. Juvenile frogs that had never been exposed to Bd were individually placed in simple choice chambers, one side of which was inoculated with Bd, while the other was not. The location of the frog (Bd-inoculated side or Bd-free side) was recorded for 4 hours. Frogs were then inoculated with Bd and subsequently cleared of infection before being trialled in the chamber a second time. In the first trial frogs spent significantly more time on the Bd inoculated side of the chamber, possibly revealing an innate attraction to Bd. This may suggest that Bd employs mechanisms that attract frogs in order to maximise opportunities for host colonisation. Conversely, in the post-recovery trial the frogs spent less time on the Bd inoculated side of the chamber than previously, and less time overall on that side, indicating that they had learned to avoid the pathogen.