Rhabdias pseudosphaerocephala infection in Bufo marinus: Lung nematodes reduce viability of metamorph cane toads

School of Biological Sciences A08, University of Sydney, NSW 2006, Australia.
Parasitology (Impact Factor: 2.56). 07/2009; 136(8):919-27. DOI: 10.1017/S0031182009006325
Source: PubMed


Cane toads (Bufo marinus) were introduced to Australia in 1935 and have since spread widely over the continent, generating concern regarding ecological impacts on native predators. Most Australian cane toad populations are infected with lung nematodes Rhabdias pseudosphaerocephala, a parasite endemic to New World (native-range) cane toad populations; presumably introduced to Australia with its toad host. Considering the high intensities and prevalence reached by this parasite in Australian toad populations, and public ardour for developing a control plan for the invasive host species, the lack of experimental studies on this host-parasite system is surprising. To investigate the extent to which this lungworm influences cane toad viability, we experimentally infected metamorph toads (the smallest and presumably most vulnerable terrestrial phase of the anuran life cycle) with the helminth. Infected toads exhibited reduced survival and growth rates, impaired locomotor performance (both speed and endurance), and reduced prey intake. In summary, R. pseudosphaerocephala can substantially reduce the viability of metamorph cane toads.

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Available from: Crystal Kelehear
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    • "To stimulate oviposition and fertilization, we injected adult cane toads (from the northeastern NSW study area) with 0.4 mL (males) or 0.8 mL (females) of Leuprorelin acetate (0.5 mg/mL; Lucrin, Abbott Australasia, Botany, NSW) diluted at 1∶20 with saline (see Kelehear et al. 2009 for details). Following deposition of eggs into water of pH 7, viable eggs containing early embryos (Gosner stage 10–13, 100 per container; Gosner 1960) were placed into 15-L solutions of the five pH treatments, with six replicates per treatment (randomly arranged in the experimental area). "
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    • "One South American parasite that was introduced to Australia with the cane toad is a lungworm, Rhabdias pseudosphaerocephala, which causes morbidity and mortality in a wide range of toad life-history stages [27], [28]. This parasite lags behind the cane toad invasion front [29], and thus the selection pressure it mediates across the population would be variable. "
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    • "\1 % survival of eggs and hatchlings in the presence of cannibalistic conspecific tadpoles: Alford et al. 1995). In addition, parasitism, cannibalism and predation by ants can reduce survival of metamorph toads (Pizzatto and Shine 2008; Kelehear et al. 2009; Ward-Fear et al. 2010). Predation by vertebrates on this invasive species remains poorly studied (but see, for example, Hamley and Georges 1985; Letnic et al. 2008; Ujvari and Madsen 2009). "
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