Apparent lack of spill-over of parasites from an invasive anuran: PCR detects in cane toads () but not in sympatric Australian native frogs.

The recent detection of a novel amoebozoan parasite ( sp. CT1) killing invasive cane toads ( in tropical Australia raises concerns of potential spill-over into native anuran populations. Considering the vulnerability of anuran communities globally, sp. CT1 may pose a serious threat to anuran biodiversity. Through PCR-based detection and molecular identification, we investigated the prevalence of spp. in the faeces and colon tissue of cane toads () and eleven native Australian frog species from a single locality in the Northern Territory. No DNA was detected in samples of native frog faeces (N = 57) or colons (N = 17). DNA was detected in 24% of 45 cane toads (95%CI 14.08-38.82). Both and sp. CT1 were present in cane toads. The failure of faecal samples to indicate spp. in infected cane toads may be due to cysts in faeces being shed intermittently, degraded before analysis, or impervious to lysis prior to DNA isolation. Our results suggest that native frogs do not carry the pathogen in an area where 20-30% of cane toads are infected with sp. CT1. We demonstrate the importance of recognising PCR inhibition prior to molecular diagnostics, and the apparent inadequacy of faecal samples for the detection of spp. in anurans.