http://www.digitaljournal.com/news/environment/african-frog-uses-chemicals-to-hide-from-killer-ants/article/364778

African frog uses chemicals to hide from killer ants

Posted Dec 29, 2013 by Tim Sandle
The West African savanna frog avoids being eaten by African stink ants by exuding a chemical that conceals the frog from the maundering ants.
African bullfrog (Pyxicephalus adspersus)
African bullfrog (Pyxicephalus adspersus)
Steven G. Johnson
African stink ants (Paltothyreus tarsatus) live in giant nests comprising of several thousand ants. They are a type of army ant, due to their aggressive predatory foraging groups, known as "raids," in which huge numbers of ants forage simultaneously over a certain area. The ants also vigorously defend their nests, biting intruders with powerful mandibles and stinging them with venom. The ants are capable of killing frogs.
One frog has a mechanism to avoid being eaten by the ants. The West African savanna frog (Phrynomantis microps) produces two short chains of amino acids — known as peptides — that trick the ants into leaving the frog alone. The frog is a type of bullfrog, also known as the pixie frog, due to its Latin name. It is found in Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, South Africa, Swaziland, Tanzania, Zambia, Zimbabwe, and possibly Democratic Republic of the Congo.
To find out about the special properties of the frog, the research team collected 13 frogs from the Pendjari Biosphere Reserve in northern Benin. Back in the lab in Germany, they needed to get samples of the chemicals, unknown at that point, secreted through the frogs’ skin. So the scientists placed a frog in a 250-milliliter beaker containing 10 milliliters of water and shook it for two minutes. When the researchers covered termites or mealworms with the frog secretions and presented the potential prey to stink ants, the ants delayed their stinging behavior.
This interesting finding has been discovered by Mark-Oliver Rödel of the Leibniz Institute for Research on Evolution and Biodiversity in Berlin. The findings have been published in the journal PLoS One. The paper is titled "Chemical Camouflage– A Frog's Strategy to Co-Exist with Aggressive Ants."