Only discovered in 2008, the tiny nematode Myrmeconema neotropicum has a highly unusal reproductive strategy. It’s so unique that sceintists cannot find any other nematode species to match it. Considering that there are over 20,000 nematode species, M. neotropicum is unique, indeed. It only lives in South African rainforests, because that is where their companions in reproduction live.
Nematodes, also called roundworms, are microscopic worms that live inside the bodies of other creatures or inside of plants. Carnivorous nematodes specializing in insects usually can eat several species but not M. neotropicum. Of course, scientists are not entirely sure if M. neotropicum does prey on other insects, but so far only one host species has been positively identified.
The Birds and the Ants
In order to reproduce, M. neotropicum relies on the ant species Cephalotes atratus, commonly called neotropical black ants, as well as numerous birds that like to eat red berries. Birds and ants are crucial to the survival of M. neotropicum. Mating is done inside of the bodies of Cephalotes atratus while it is still a pupae. The female lays eggs. But the body of one ant is not enough to feed the next generation.
The solution is to use birds to taxi the eggs to other ants. But how to get the birds to eat the ants? Ants are not desirable food items for birds of the South American rainforests. They are the walking equivalent of celery in that it usually makes them burn more calories to eat an ant than the ant body can provide. Also, many ant species sting or seem to taste terrible to bird palates. The solution is to make the ant not look like an ant but a berry.
The abdomen or gaster of an infected Cephalotes atratus turns from its normal black into bright red like a berry. This is to attract berry-eating birds to eat the ants. Scientists still are not sure exactly how M. neotropicum manages this colorful transformation. For decades, biologists had just assumed these strange red-bottomed black ants were another species.
Birds see the berry red behinds of the ants and eat the ants, or at least the behind where the nematode eggs are. The eggs then pass through the bird’s digestive system unharmed and are deposited all over the rainforest inside of the bird’s manure.
And guess just what is the preferred food of Cephalotes atratus? Bird manure. The ants eat the egg-laden bird manure back to their colonies, including their larvae. The eggs hatch inside of the ant larvae, then mature and mate white the ant is only a pupae. Then the whole cycle starts again.
University of Nebraska-Lincoln. “Nematodes in General: What Are Namtodes?” http://nematode.unl.edu/Wormgen.htm
Science Daily. “Ant Parasite Turns Host Into Ripe Red Berry, Biologists Discover.” Jan. 21, 2008. http://www.sciencedaily.com/releases/2008/01/080116142805.htm
Science Blog. “Berry Butts: Parasitized Black Ants Resemble Red Berries.” http://scienceblogs.com/grrlscientist/2008/01/berry_butts.php