Frog decline, frog malformations, and a comparison of frog and human health

Cohen, Michael

doi:10.1002/ajmg.10002

Cited by 38 publications

(31 citation statements)

References 61 publications

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“…global warming and diseases, the major cause appears to be chemical pollution owing to the increased contamination of natural water bodies by agrochemicals (Green, 1999;Cohen 2001;Daniels, 2003;Hayes et al, 2006;Wake, 2007). Field studies have indicated that there is a correlation between the use of chemical pesticides and emergence of the amphibian larvae with developmental deformities in Northern America (Glare and O'Callaghan, 1999).…”

Section: Amputation Of Tail and Treatmentmentioning

confidence: 96%

“…In recent years, owing to water pollution, there has been an increase in the production of amphibian fauna with gross malformations aff ecting survival ability, leading to overall decline in populations (Wake, 1991;Hayes et al, 2003). These have prompted serious concern regarding the biological status of many anuran species (Green, 1999;Cohen, 2001;Daniels, 2003;Hayes et al, 2006).…”

Section: Introductionmentioning

confidence: 97%

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Developmental disruptions induced by insect growth regulator (Novaluron) in Bufo melanostictus tadpoles

Pancharatna

Ghodageri

Deshpande

et al. 2010

J of Applied Toxicology

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Novaluron is an insect growth regulator (IGR) used against fruit-borers and domestic pests. In this study, effects of different concentrations (0.5, 0.75, 1.0, 1.5 microg l(-1)) of novaluron on the tail regeneration, limb development and metamorphosis were examined in Bufo melanostictus. Thyroxine (1.0, 2.0, 3.5, 5.0 microg l(-1)), which promotes amphibian development/metamorphosis, and vitamin A (5, 20, 40, 60 IU l(-1)), which disrupts development and induce polymelia, were used for comparison. Bufo melanostictus tadpoles were raised in the laboratory from eggs collected around Dharwad in August 2007. The tail of tadpoles was amputated at limb-bud stage under ether anesthesia. Ten tadpoles were exposed to each concentration of chemicals in triplicate for 5 days and then reared in conditioned water. Tadpoles were fed on boiled spinach. In controls (tadpoles exposed to ringer solution), the tail regenerated on the 5th day, hind-limbs and fore-limbs appeared on days 15 and 24, respectively; metamorphosis was complete on the 30th day. In 1 and 2 microg l(-1) thyroxine exposed tadpoles, regeneration of tail, development of limbs and metamorphosis were preponed to the 4th, 7th, 11th and 23rd day respectively. Exposure to vitamin A resulted in the regeneration of laterally drooped tails, delay in limb development and arrest of metamorphosis in all the concentrations used. Novaluron at lower dose (0.5 microg l(-1)) was not effective, but at 0.75 microg and higher concentrations it elicited results comparable to those of vitamin A. The study indicates that novaluron interferes with amphibian development if found as contaminant in the water bodies where amphibians live and reproduce.

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Section: Amputation Of Tail and Treatmentmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 97%

Developmental disruptions induced by insect growth regulator (Novaluron) in Bufo melanostictus tadpoles

Pancharatna

Ghodageri

Deshpande

et al. 2010

J of Applied Toxicology

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“…These causes may occur synergistically (Kiesecker, 2002) and may relate to recent human-induced environmental damage (Blaustein and Johnson, 2003;Lannoo, 2008). The rate of malformed frogs in nature seems to have increased in recent years (Cohen Jr., 2001;Blaustein and Johnson, 2003;Schoff et al, 2003;Lannoo, 2008) and malformed frogs may indicate degraded environmental health (Ouellet et al, 1997;Roy, 2002).…”

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confidence: 96%

The Archipelago of Fernando de Noronha: An Intriguing Malformed Toad Hotspot in South America

Toledo

Ribeiro²

2009

EcoHealth

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Malformed anurans raise concern among scientists, because deformities may relate to the recent global crisis among amphibian populations, although declining populations also may be associated with other causes (e.g., diseases, over-exploitation, and land use/land cover change). We examined a sample of toads (Rhinella jimi, Bufonidae) from an introduced population in the Archipelago of Fernando de Noronha, Brazil where malformations of anurans were thought to be high. Our sample of 159 specimens from the site revealed that 44.6% of all specimens had one or more malformations. Incidence of malformed toads on the mainland sites was substantially lower: 10.5% at Itamaracá, and 3.7% at Propriá. We describe the malformations observed, including six undescribed types of malformation of anurans, and we pose possible hypotheses to explain this high incidence of malformed toads. In addition to existing hypotheses, we suggest for the first time the hypothesis that lack of predation pressures contributes to numbers of malformed toads. We indicate the need of specific studies to understand the causes of malformations in the R. jimi population of Fernando de Noronha, which is thought to be extreme foci of malformed amphibians in the world. Our results may improve local conservation action plans as this is an alien population that may be affecting endemic fauna, and may affect populations in other parts of the world, because toad species of the genus Rhinella are recognized as exceptional colonizers. More importantly, unknown variables in these toads' environment are evidently affecting toads during development, which should be a concern for all species that inhabit the area, perhaps even humans.

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“…If the survival of Pleurogenoides is strongly associated to water frogs as the key host within the life-cycle, Pleurogenoides might soon become a vanishing genus at least in Europe because of the current widespread frog population decline [16]. In that case the absence of Pleurogenoides larval stages in the snails will open free ecological niches -chances to use these snails as hosts -for other fl ukes.…”

Section: Discussionmentioning

confidence: 99%

A case of a facultative life-cycle diversification in the fluke Pleurogenoides sp. (Lecithodendriidae, Plagiorchiida)

Hassl

2010

Wien Klin Wochenschr

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Numerous specimens of the native, intestinal digenean fluke Pleurogenoides sp. (Lecithodendriidae, Plagiorchiida), a genus known for the simultaneous co-existence of genuine adults and progenetic, adult-like metacercaria, were found by chance parasitizing in the oesophagus of a recently imported, tropical Bristly Bush Viper (Atheris hispida). The snake had before been force-fed with native water frogs, the assumed definitive host of these flukes. Hence water frogs act as the second intermediate host or as a paratenic host for Pleurogenoides flukes, as they must house progenetic fluke larvae, which develop to genuine adults when transmitted to an appropriate consecutive host, the ancestral definitive host, a reptile. The European Pleurogenoides fluke species seem to display a facultative life-cycle diversification, they can adjust their life-history strategy according to their immediate transmission opportunities. This phenotypic plasticity allows the parasite to respond quickly to any changes in the abundance of a host; usually this biological oddity results in a life-cycle truncation by the elimination of the definitive host.

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Frog decline, frog malformations, and a comparison of frog and human health

Cited by 38 publications

References 61 publications

Developmental disruptions induced by insect growth regulator (Novaluron) in Bufo melanostictus tadpoles

Developmental disruptions induced by insect growth regulator (Novaluron) in Bufo melanostictus tadpoles

The Archipelago of Fernando de Noronha: An Intriguing Malformed Toad Hotspot in South America

A case of a facultative life-cycle diversification in the fluke Pleurogenoides sp. (Lecithodendriidae, Plagiorchiida)

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