Having dangerous and potentially deadly enemies, it is very useful to move unnoticed. Harry Potter and his friends need a magic cloak for that purpose, making them invisible. The Red Rubber Frog, living in the savannas of West Africa, occurs within the colonies of poisonous and aggressive ants, without being harmed by them. Now researchers of the Museums für Naturkunde in Berlin, together with their colleagues from Frankfurt, Würzburg and Switzerland, have identified and synthesized the substances which are used by the frog to inhibit the aggressive behaviour of the ants.
The Red Rubber Frog has no easy life. This species inhabits savannas sometimes being without rain for half a year. In order to not dry up, the frog needs to hide underground in humid soil. As this frog can’t dig himself into the earth, it is completely dependent to use already existing burrows and cracks. However, those are often already occupied by aggressive ants. One of these species, the African Scavenger Ant, reaching 2.5 cm and smelling like sulphur, is particularly aggressive, possessing powerful mandibles and a sting connected with a venom gland. These ants hunt and kill other frogs; however, the Red Rubber Frog even lives in middle of their colonies, apparently not being recognized as an intruder.
Mark-Oliver Rödel, researcher at the Museum für Naturkunde in Berlin, and his colleagues supposed that the frogs make use of chemical substances in their skin in order to move unrecognized between the ants, these mainly relying on their chemical perception of their environment. In the newest issue of the scientific journal PLOS ONE these researchers now report on a set of experiments with which they discovered hitherto unknown substances, two new peptides, which contribute to the effect that the ants don’t attack the frog. In order to prove that it is these substances “taming” the ants, the synthesized the two peptides and successfully tested them in Africa with wild Scavenger Ants. For this purpose they offered the ants another favourite prey, termites, either treated or not treated with these peptides. Treated termites were ignored by the ants or only attacked with some delay compared to untreated termites.
The researchers assume that the frogs are able to produce these substances by themselves, and do not need particular food in order to synthesize it (in contrast to poison dart frogs which relay on particular arthropod diets in order to maintain being poisonous). Even freshly metamorphed rubber frogs move unharmed between the ants and adults kept for years in captivity with artificial food didn’t loose their chemical protection.
The authors of this study believe that the substances discovered by them, theoretically could also be useful to tame other aggressive insect behaviour.
Rödel, M.-O., C. Brede, M. Hirschfeld, T. Schmitt, P. Favreau, R. Stöcklin, C. Wunder & D. Mebs (2013): Chemical camouflage – a frog’s strategy to co-exist with aggressive ants. – PLOS ONE. http://dx.plos.org/10.1371/journal.pone.0081950