Mites give poison frogs their toxic might

This is a video, in English with Portuguese subtitles, about the reproduction of the poison frog Oophaga pumilio.

From New Scientist:

Mites give poison frogs their toxic might

* 12:27 15 May 2007
* NewScientist.com news service
* Roxanne Khamsi

Poison frogs of Central America acquire their toxic arsenal by extracting it from the mites they eat – not by synthesising it themselves, a new study reveals.

The frogs somehow store the chemical weaponry in their skin and release it when a predator, such as a snake, attacks.

The finding explains why the amphibians lose their toxic shield when removed from their natural habitat.

John Daly of the National Institutes of Health in Bethesda, Maryland, US, and colleagues collected Oophaga pumilio frogs, which are found throughout southern Nicaragua, Costa Rica and parts of Panama.

The team also collected numerous insect samples from the leaves in the frogs’ habitat.

Unlike Oophaga pumilio frogs raised in captivity, those in the rainforest had high levels of poisonous alkaloids in their skin.

The mites – tiny arachnids – that Daly’s team analysed contained an astonishing range of alkaloids: 84 in total, 42 of which were also detected in Oophaga pumilio.

The team also discovered that the mites produced the frogs’ namesake toxin, the “pumilio” alkaloid.

Taste not a good test

“The dogma in the field has been that ants have been the most important dietary source of these toxins,” says Ralph Saporito of Florida International University in Miami, Florida, US, who helped conduct the research.

“Our results suggest it’s the mites instead. We’ve found a larger number and diversity in alkaloids in mites.” …

In January, it was revealed that snakes in Japan store the venom of the poisonous toads they eat to use in their own defensive arsenal.

See also here.

This is another Oophaga pumilio video. It is called Strawberry poison dart frog (Dendrobates pumilio) calling in Costa Rica.

Miguel Vences was dissecting a frog no bigger than his fingernail when he smelled an unusual acrid smell. “Maybe it can be compared with vinegar,” he says. “It is a totally different smell, but somehow the same kind of bitter-burning feeling when you get it into your nose.” He remembered the distinctive scent from his experiences with other species of frogs, all of which have powerful poisons in their skins. He reasoned that the species he was cutting open – a beautiful Monte Iberia eleuth – was similarly armed with toxins. A chemical analysis of its skin confirmed Rodriguez’s suspicion. The frog’s skin was laced with toxins, including a group of muscle-paralysing poisons called pumiliotoxins that are common among poison dart frogs: here.