May 29

In a letter to Nature magazine, researchers have expressed their concern over the appearance of a non-native toad species, the Asian common toad, in Madagascar.

The Asian common toad (Duttaphrynus melanostictusi) is a close relative of the cane toad (Rhinella marina), an invasive toad species that rapidly spread across Australia after its introduction in the 1930s, and has devastated many native fauna and flora populations. First seen on Madagascar in March, the Asian common toad has been sighted several times in areas close to Toasmasina, the main port of the island nation. Worryingly, there have also been sightings of the amphibian just 25 kilometres from the Betampona Nature Reserve and short distances from other biodiversity hotspots. The dispersal of this species is not just limited to Madagascar and it is thought that populations may have also become established in other areas. One of the authors of the letter, Jonathan Kolby, of James Cook University in Queensland, Australia, said, ”There is now a high dispersal risk of these toads spreading from Madagascar to other Indian Ocean islands such as the Mascarene Islands, Comoros, and Seychelles.”

It is thought that populations may have also become established on other Indian Ocean islands, such as the Mascarene Islands

It is thought that the Asian common toad could have various negative impacts on the fauna of Madagascar, including spreading diseases such as ranavirus and chytridiomycosis to native amphibians and competing with them for food and breeding areas. This toad species is poisonous and is known to be toxic to animals that ingest it. Snakes are thought to be one of the animal groups most at risk from the invasion and there are over 50 endemic snake species on Madagascar, including the Madagascar ground boa. Other endemic species including fossas, lemurs, and birds will also be put at risk should the population of this harmful amphibian become established. Kolby also said, “It’s worrying because Madagascar has amazing endemic biodiversity – plants, animals, and amphibians that are found nowhere else. And this one species has the propensity to damage that.”

95 percent of the reptiles on Madagascar are endemic to the island, including the Madagascan ground boa

As well as being a threat to the animals of Madagascar, the Asian common toad is also a threat to the human population as it is known to contaminate drinking water and transmit parasites. After the devastation the cane toad has caused in Australia, it is thought that immediate action is required on Madagascar to prevent history from repeating itself. Kolby said, “The question is, can we still eradicate them? Have we caught it soon enough that eradication could be a feasible option? Obviously we all hope the answer is yes.” Suggested methods of eradication include removing adult toads, draining breeding ponds, and installing fences to prevent the toads from reaching water where they would be able to breed. Highlighting the urgency of the situation, Kolby said, ”Time is short, so we are issuing an urgent call to the conservation community and governments to prevent an ecological disaster.”

In Australia, the introduced cane toad is responsible for the declines of many native species, including the Near Threatened brush-tailed phascogale

Read more on this story at Nature – Toxic toads threaten ‘ecological disaster’ for Madagascar.

View images and videos of Madagascan species on ARKive.

Hannah Mulvany, ARKive Content and Outreach Officer

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