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WFS 433/533 April 12, 2012

I. What is ?

II. New County, MN

III. History and General information

IV. Hosts, Life Cycle, and Malformations

V. Research

VI. Declines and Future Research

Introduction

“ is a parasite that turns into monsters and feeds them to birds”

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 Trematode parasite  Phylum- Platyhelminthes  Indirect, complex life cycle  Class-  Distinctive esophageal  Order- Echinostomida diverticula  Family-  Hermaphroditic  - Ribeiroia  Known to cause lilibmb  SSipecies- onddtatrae, mariiini, malformations in congolensis species • Subspecies: R.m. guadeloupensis

 Biology field trip in Le Seur, MN  Conversation over causes Summer 1995  Likely to be a result of several  30-40% deformed in Ney pond factors (MN Pollution Control Agency)  Habitat alteration + Ribeioria =  Widespread reports of Increase in ddfitieformities deformities shocked public

 1st linked to amphibian malformations in 1990 (Ruth and Sessions)

Confirmed by Johnson et al. 2001

 Preserved specimens 1946

 Mostly hindlimb abnormalities Supernumerary, usually unilateral but when bilateral, assymmetrical

 60 species in 46 states and 4 provinces (Mostly anuran) http://www.npwrc.usgs.gov/narcam

 Different species respond differently to identical R. ondatrae numbers (P. treefrogs vs. W. Toads, Johnson et al. 2001)

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But how do we go from this

To that

 First intermediate hosts: Planorbid snails (Rediae)

 Second intermediate hosts: Amphibians or Fish (CCiercariae)

 Definitive hosts: Birds or Mammals (Metacercariae)

Ribeiroia as a biological control? Biomphalaria glabrata

a) Rediae Schistosoma mansoni b) Cercariae c) Metacercariae d) Adult parasite

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 Disruption of developing and regenerating tissues Sessions and Ruth (1990)  Two hypotheses for improper limb development

• Mechanical: parasites disturb the arrangement of growing limb cells, leading to abnormal limb formation or even duplication • Chemical: Ribeiroia actively produces a compound that interferes with a retinoid- sensitive signaling pathway, stimulating or inhibiting continued limb growth Maden (1996) Johnson (1999) May occur individually or in concert. Malformation is dependent upon : number of parasites timing of exposure Johnson (2001) Sweet planet video  Polymely, ectromely, polydactyly, etc.

 Malformed Hyla regilla and Ambystoma  Resin beads (150-200μm) inserted into macrodactylum in Northern California captive Xenopus laevis and Ambystoma mexicanum  Adults/juveniles and larval stages collected for analysis  Control limb buds

 Supporting Evidence  Substantial limb 1. Visible disruption of hind limb-forming abnormalities region by cysts in young tadpoles 2. Limb abnormalities and presence and  Close physical localized concentrations of metacercariae association b/t in two unrelated species of amphibians in beads and the same pond. duplicated limb structures

 Western toads exposed to different levels of cercariae Control, Light, Intermediate, and Heavy  67% of exposed had malformations.  86% in heavy treatment had malformations  Survivorship in all treatment groups decli ned sh arpl y with parasit e load

Survivorship as exposure Freq. of abnorm. as exposure

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 Not associated with widespread population declines but…….

 Emergence due to the changing ecology of the habitats of its hosts 1)Highly productive due to run-off and lead to increased algal production increased populations of snail hosts 2) in the number of artificial impoundments and in natural wetlands 3) Other hosts (birds, amphibians) typically found in artificial systems

 Other factors causing malformations: UV-B radiation, pesticides, nutrient run-off, predators (introduced and natural)

 Interaction of factors

 Has potential to be a cause of amphibian declines Kiesecker (2002) Thiemann (2000)

 Co-evolutionary interactions between R. ondatrae and its hosts

 Parasite/host/environment interactions

 Differing species

 Possibility of increase in geographic prevalence of the parasite

 Hoppe, D.M. 2000. History of Minnesota abnormalities: do recent findings represent a new phenomenon? J. Iowa Acad. Sci. 107: 86-89.  Hoppe, D.M. 2004. Linking malformations to amphibian declines: history of malformed anurans in Minnesota and interspecific differences in their occurences. In Declining Amphibians: A United States’ Response to the Global Phenomenon (Lannon, M.J., ed.), University of California Press, Berkeley, California.  Johnson P.T.J. et al. 1999. The effect of trematode infection on amphibian limb development and survivorship. Science 284: 802-804.  Johnson, P.T.J., and Lunde K.B. 2001 Trematode parasites and amphibian limb malformations in the western U.S.: are they a concern? In Status and conservation of U.S. amphibians. Edited by M.J. Lannoo. University of California Press.  Johnson, P.T.J., et al. 2001. Ribeiroia ondatrae (Trematoda:Dignea) infection induces severe limb malformations in western ttdoads (BBfufo boreas). Can. J. Zool . 79: 370-379.  Johnson P.T.J., Sutherland, D.R., Kinsella, J.M., and K.B. Lunde. 2004. Review of the Trematode Genus Ribeiroia (Psilostomidae): Ecology, Life History and Pathogenesis with Species Emphasis on the Amphibian Malformation Problem. Advances in Parasitology: 57: 191-253  Kiesecker, J.M. 2002. Synergism between trematode infection and pesticide exposure: A link to amphibian deformities in nature? Proc. Natl. Acad. Sci. U.S.A. 99: 9900-9904.  Maden, M. 1996. Retinoic acid in development and regeneration. J. Bioscience 21, 299-312  Sessions, S.K. and Ruth, S.B. 1990. Explaination for naturally occuring supernumerary limbs in amphibians. J. Expo. Zool. 254: 38-47.  Ouellet, M., Bonin, J. , Rodrigue, J., DesGranges, J.L., Lair, S. 1997. Hindlimb deformities (ectromelia, ectrodactyly) in free living anurans from agricultural habitats. J. Wildl. Dis. 41:37-66  Stopper, G.F. et al. 2002. How trematodes cause limb deformities in amphibians. J. Expo. Zool. 294: 252-263.  Sutherland, D.R. 2004. Parasites of North American Anurans. In Declining Amphibians: A United States’ Response to the Global Phenomenon (Lannon, M.J., ed.), University of California Press, Berkeley, California.  Thiemann, G.W. and Wassersug, R.J. 2000. Patterns and consequences of behavioural responses to predators and parasites in Rana tadpoles. Biol. J. Linn. Soc. 71: 513-528.

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