Berkeley -- A newly discovered parasite so dramatically transforms its host, an ant, that the ant comes to resemble a juicy red berry, ripe for picking, according to a report accepted for publication in The American Naturalist. This is the first example of fruit mimicry caused by a parasite, the co-authors say.
Presumably, the dramatic change in appearance and behavior tricks birds into eating infected ants - parasites and all - so that the bird can spread the parasite in its feces. The fruit-eating birds' droppings, which are mostly seeds and insect parts, are gathered by other ants who then feed and unwittingly infect their young.
This bizarre lifecycle of a parasitic nematode, or roundworm, plays out in the high canopy of tropical forests ranging from Central America to the lowland Amazon, according to Robert Dudley, a professor of integrative biology at the University of California, Berkeley.
"It's just crazy that something as dumb as a nematode can manipulate its host's exterior morphology and behavior in ways sufficient to convince a clever bird to facilitate transmission of the nematode," Dudley said.
"It's phenomenal that these nematodes actually turn the ants bright red, and that they look so much like the fruits in the forest canopy," said co-author Stephen P. Yanoviak, an insect ecologist and assistant professor of biology at the University of Arkansas at Little Rock, who noted that numerous tropical plants produce small red, orange and pink berries. "When you see them in the sunlight, it's remarkable."
Dudley chanced upon the infected ants while he, Yanoviak and ant ecologist Michael E. Kaspari of the University of Oklahoma in Norman were studying the gliding ability of a species of ant, Cephalotes atratus, common in the tropical forest canopy. Three years ago, their team described the ant's ability to make mid-air maneuvers so that, if knocked off a branch, they can glide toward the tree trunk, grab hold
|Contact: Robert Sanders|
University of California - Berkeley