Eggs which were removed from a chytrid- infected population of Valcheta frogs shortly after laying and then hatched in a clean environment resulted in juveniles free of the fungus.Fil: Arellano, Maria Luz. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Velasco, Melina Alicia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martínez Aguirre, Tomás. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zarini, Ornella. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Belasen, Anat M.. University of Michigan; Estados UnidosFil: James, Timothy Y.. University of Michigan; Estados UnidosFil: Kacoliris, Federico Pablo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Arellano, Maria Luz

Belasen, Anat M.

James, Timothy Y.

Kacoliris, Federico Pablo

Martínez Aguirre, Tomás

Velasco, Melina Alicia

Zarini, Ornella

English

Eggs which were removed from a chytrid- infected population of Valcheta frogs shortly after laying and then hatched in a clean environment resulted in juveniles free of the fungus.Facultad de Ciencias Naturales y Muse

Arellano, María Luz

El Servicio de Difusión de la Creación Intelectual

M.L. Arellano et al. / Conservation Evidence (2018) 15, 38 
38 
ISSN 1758-2067 
 
Conservation Evidence is an open access online journal devoted to publishing the evidence on the effectiveness of management interventions. The other 
papers from Conservation Evidence are available from www.ConservationEvidence.com. The pdf is free to circulate or add to other websites and is licensed 
under the Creative Commons Attribution 4.0 International License http://creativecommons.org/licenses/by/4.0/. 
Management strategy to avoid chytrid fungus infection in egg clutches of the Valcheta 
frog Pleurodema somuncurense  
 
María L. Arellano1*,  Melina A. Velasco1, Tomas Martínez Aguirre1, Ornella Zarini1, Anat M. Belasen2, Timothy Y. 
James2  & Federico P. Kacoliris1  
1 Sección Herpetología, Departamento Zoología de Vertebrados, CONICET, Facultad de Ciencias Naturales y Museo, Calle 122 y 60 s/n. La Plata 
(1900), Argentina 
2 Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA 
 
SUMMARY: Eggs which were removed from a chytrid-
infected population of Valcheta frogs shortly after laying and 
then hatched in a clean environment resulted in juveniles 
free of the fungus. 
 
BACKGROUND: An ex-situ colony of the critically endangered 
Valcheta frog Pleurodema somuncurense (Cei 1969) was 
established in order to facilitate a species reintroduction 
programme. The colony was founded with forty frogs from the 
Valcheta stream, located in the Somuncura Plateau (40°59' S,  
66°40'36 W), northern Patagonia, Argentina.  
Individuals of the colony were previously infected with 
chytrid fungus Batrachochytrium dendrobatidis (Bd; Arellano 
et al. 2017), and although an unsuccessful Bd cleaning 
treatment had been applied a few months before (Arellano et 
al. 2018), several clutches of eggs were laid in Bd-infected 
terrariums. We therefore tested a management strategy aimed 
at reducing or even avoiding possible infection of tadpoles and 
juveniles. 
 
ACTION: The ex-situ colony was established in laboratory 
terrariums (80 x 27 cm), each containing eight frogs with a 2/1 
female/male sex ratio. Eighteen months after the colony was 
established, four adult pairs of frogs from three different 
terrariums laid a total of five clutches of eggs. Before these 
reproductive events, a Bd cleaning treatment was applied 
without success; adults carried an average Bd infection load of 
2.3 zoospore genomic equivalents. To avoid potential possible 
cross-infection, the eggs were separated from adults just after 
laying and placed in previously disinfected terrariums. Once 
the tadpoles reached Gosner stage 36 (Gosner 1960), ten 
individuals were randomly checked for Bd infection by 
examination of fresh unstained oral disks under a 
stereomicroscope. Once the tadpoles metamorphosed, ten 
juvenile frogs were swabbed and analyzed for infection using 
Bd-qPCR (Boyle et al. 2004, Kerby et al. 2013).  
 
CONSEQUENCES & DISCUSSION: Each clutch consisted of 
about 300 viable eggs, of which 160 reached tadpole stage and 
100 survived to become adults. Direct examination of the oral 
disks of tadpoles and qPCR analysis of juveniles were both 
negative for the presence of Bd in all ten individuals tested. 
Since Bd has not yet been observed in eggs (Bancroft et al. 
2011), our results suggest that removing eggs from infected 
adults may be an effective management strategy to reduce or 
even avoid infection in individuals bred in captivity.  
 
 
 
*
To whom correspondence should be addressed: mluzarellano@gmail.com 
REFERENCES: 
Arellano M.L., Velasco M.A., Martínez Aguirre T., Zarini O., 
Belasen A.M., James T.Y. & Kacoliris  F.P. (2018). 
Treatment of adults of the Valcheta Frog Pleurodema 
somuncurense for Chytrid fungus. Conservation Evidence, 
15, 37.  
Arellano M.L., Velasco M.A., Kacoliris F.P., Belasen A.M. & 
James T.Y. (2017) First Record of Batrachochytrium 
dendrobatidis in Pleurodema somuncurense, a Critically 
Endangered Species from Argentina. Herpetological 
Review, 48 (1). 
Bancroft B., Han B.A., Searle C.L., Biga L.M., Olson D.H., 
Kats L.B. et al. (2011) Species-level correlates of 
susceptibility to the pathogenic amphibian fungus 
Batrachochytrium dendrobatidis in the United States. 
Biodiversity and Conservation, 20, 1911-1920. 
Boyle D.G., Boyle D.B., Olsen V., Morgan J.A.T. & Hyatt 
A.D. (2004) Rapid quantitative detection of 
chytridiomycosis (Batrachochytrium dendrobatidis) in 
amphibian samples using real-time Taqman PCR assay. 
Diseases of Aquatic Organisms, 60, 141-148. 
Cei J.M. (1969) The Patagonian telmatobiid fauna of the 
volcanic Somuncura Plateau of Argentina. Jounal of 
Herpetology, 3, 1-18. 
Gosner K.L. (1960). A simplified table for staging anuran 
embryos and larvae with notes on identification. 
Herpetologica 16, 183-190. 
Kerby J.L., Schieffer A., Brown J.R. & Whitfield S. (2013) 
Utilization of fast qPCR techniques to detect the 
amphibian chytrid fungus: a cheaper and more efficient 
alternative method. Ecology and Evolution, 4, 162-166. 


Management strategy to avoid chytrid fungus infection in egg clutches of the Valcheta frog Pleurodema somuncurense

CONICET Digital

M.L. Arellano et al. / Conservation Evidence (2018) 15, 38 38 ISSN 1758-2067  Conservation Evidence is an open access online journal devoted to publishing the evidence on the effectiveness of management interventions. The other papers from Conservation Evidence are available from www.ConservationEvidence.com. The pdf is free to circulate or add to other websites and is licensed under the Creative Commons Attribution 4.0 International License http://creativecommons.org/licenses/by/4.0/. Management strategy to avoid chytrid fungus infection in egg clutches of the Valcheta frog Pleurodema somuncurense   María L. Arellano1*,  Melina A. Velasco1, Tomas Martínez Aguirre1, Ornella Zarini1, Anat M. Belasen2, Timothy Y. James2  & Federico P. Kacoliris1  1 Sección Herpetología, Departamento Zoología de Vertebrados, CONICET, Facultad de Ciencias Naturales y Museo, Calle 122 y 60 s/n. La Plata (1900), Argentina 2 Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA  SUMMARY: Eggs which were removed from a chytrid-infected population of Valcheta frogs shortly after laying and then hatched in a clean environment resulted in juveniles free of the fungus.  BACKGROUND: An ex-situ colony of the critically endangered Valcheta frog Pleurodema somuncurense (Cei 1969) was established in order to facilitate a species reintroduction programme. The colony was founded with forty frogs from the Valcheta stream, located in the Somuncura Plateau (40°59' S,  66°40'36 W), northern Patagonia, Argentina.  Individuals of the colony were previously infected with chytrid fungus Batrachochytrium dendrobatidis (Bd; Arellano et al. 2017), and although an unsuccessful Bd cleaning treatment had been applied a few months before (Arellano et al. 2018), several clutches of eggs were laid in Bd-infected terrariums. We therefore tested a management strategy aimed at reducing or even avoiding possible infection of tadpoles and juveniles.  ACTION: The ex-situ colony was established in laboratory terrariums (80 x 27 cm), each containing eight frogs with a 2/1 female/male sex ratio. Eighteen months after the colony was established, four adult pairs of frogs from three different terrariums laid a total of five clutches of eggs. Before these reproductive events, a Bd cleaning treatment was applied without success; adults carried an average Bd infection load of 2.3 zoospore genomic equivalents. To avoid potential possible cross-infection, the eggs were separated from adults just after laying and placed in previously disinfected terrariums. Once the tadpoles reached Gosner stage 36 (Gosner 1960), ten individuals were randomly checked for Bd infection by examination of fresh unstained oral disks under a stereomicroscope. Once the tadpoles metamorphosed, ten juvenile frogs were swabbed and analyzed for infection using Bd-qPCR (Boyle et al. 2004, Kerby et al. 2013).   CONSEQUENCES & DISCUSSION: Each clutch consisted of about 300 viable eggs, of which 160 reached tadpole stage and 100 survived to become adults. Direct examination of the oral disks of tadpoles and qPCR analysis of juveniles were both negative for the presence of Bd in all ten individuals tested. Since Bd has not yet been observed in eggs (Bancroft et al. 2011), our results suggest that removing eggs from infected adults may be an effective management strategy to reduce or even avoid infection in individuals bred in captivity.     *To whom correspondence should be addressed: mluzarellano@gmail.com REFERENCES: Arellano M.L., Velasco M.A., Martínez Aguirre T., Zarini O., Belasen A.M., James T.Y. & Kacoliris  F.P. (2018). Treatment of adults of the Valcheta Frog Pleurodema somuncurense for Chytrid fungus. Conservation Evidence, 15, 37.  Arellano M.L., Velasco M.A., Kacoliris F.P., Belasen A.M. & James T.Y. (2017) First Record of Batrachochytrium dendrobatidis in Pleurodema somuncurense, a Critically Endangered Species from Argentina. Herpetological Review, 48 (1). Bancroft B., Han B.A., Searle C.L., Biga L.M., Olson D.H., Kats L.B. et al. (2011) Species-level correlates of susceptibility to the pathogenic amphibian fungus Batrachochytrium dendrobatidis in the United States. Biodiversity and Conservation, 20, 1911-1920. Boyle D.G., Boyle D.B., Olsen V., Morgan J.A.T. & Hyatt A.D. (2004) Rapid quantitative detection of chytridiomycosis (Batrachochytrium dendrobatidis) in amphibian samples using real-time Taqman PCR assay. Diseases of Aquatic Organisms, 60, 141-148. Cei J.M. (1969) The Patagonian telmatobiid fauna of the volcanic Somuncura Plateau of Argentina. Jounal of Herpetology, 3, 1-18. Gosner K.L. (1960). A simplified table for staging anuran embryos and larvae with notes on identification. Herpetologica 16, 183-190. Kerby J.L., Schieffer A., Brown J.R. & Whitfield S. (2013) Utilization of fast qPCR techniques to detect the amphibian chytrid fungus: a cheaper and more efficient alternative method. Ecology and Evolution, 4, 162-166. 

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Management strategy to avoid chytrid fungus infection in egg clutches of the Valcheta frog Pleurodema somuncurense

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