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Widespread Ranavirus and Perkinsea infections in Cuban Treefrogs (Osteopilus septentrionalis) invading New Orleans, USA

Citation

Savage, Anna et al. (2021), Widespread Ranavirus and Perkinsea infections in Cuban Treefrogs (Osteopilus septentrionalis) invading New Orleans, USA , Dryad, Dataset, https://doi.org/10.5061/dryad.7wm37pvs8

Abstract

Invasive species can negatively impact ecosystems in numerous ways, including vectoring pathogenic organisms. In amphibians, a lineage globally threatened by multiple pathogens, this spread of disease via invasive species could contribute to declines in native populations. The Cuban Treefrog (Osteopilus septentrionalis) is invasive in the southeastern USA. To assess whether O. septentrionalis is a potential reservoir host for the pathogens Batrachochytrium dendrobatidis (Bd), Ranavirus (Rv), and Perkinsea (Pr), we sampled 82 individuals from a recently invaded site in New Orleans, Louisiana, USA. We used quantitative PCR to assess prevalence and intensity of Bd, Rv and Pr in mouthparts and tail clips from 22 larvae and in toe clips from 60 metamorphosed frogs. We compared infection prevalence and intensity across host characteristics, including Fulton’s body condition (K), sex, and life stage. None of the individuals were infected with Bd, 72% were infected with Rv, and 44% were infected with Pr. Twenty-three individuals (28%) were co-infected with Rv and Pr, but co-infection did not significantly predict the prevalence or intensity of either Rv or Pr. Although we did not observe any disease signs, Pr infections were significantly associated with lower body condition, suggesting sub-lethal fitness costs. Our study establishes that invasive O. septentrionalis in New Orleans are infected with two pathogens of global concern for amphibians. Understanding host-pathogen dynamics in O. septentrionalis in Louisiana is a critical step towards understanding how this invasive species could threaten amphibian biodiversity in the region by transmitting infectious pathogens.

Methods

We collected Cuban Treefrogs (Osteopilus septentrionalis) from Audobon Zoo and Riverview Park in New Orleans, Louisiana, USA, during visual surveys and we then subsampled 15 individuals per sampling occasion for disease analysis. We collected toe clips (adults and juveniles) and tail clips/mouth parts (tadpoles only) from these individuals and extracted the DNA from these tissues using a Qiagen Dneasy kit based on the manufacturers protocols. We then used established qPCR protocols for three major amphibian pathogens in the southeastern United States, Perkinsea (Pr), Ranavirus (Rv) and Batrachochytrium dendrobatidis (Bd), to determine the presence and infection intensity (in genomic equivalents) for each pathogen for each individual that we subsampled. We then compared the infection presence and infection intensity against a number of demographic categories collected on each individual including: location, month (this excluded tadpoles/larvae as they were only collected during a single month), age class, sex, K (a fitness coefficient), Co-infection status, and the overall prevalence for each pathogen.

Usage Notes

Please see uploaded ReadMe file.