for National Geographic News
Fruit pickers beware. That red berry might actually be an infested ant's rear end.
Scientists have discovered a parasite in the tropical forests of Central and South America that makes its ant hosts look like juicy, red berries ripe for the picking.
Presumably the change in appearance tricks foraging birds into eating the otherwise unappetizing ants—parasites and all. The parasites travel through the birds' guts intact and are pooped out, which allows them to spread.
"These ants, in nature, go out and collect bird feces," explained Steve Yanoviak, an insect ecologist at the University of Arkansas in Little Rock.
The finding is the first known example of fruit mimicry caused by a parasite, he and his colleagues conclude in their study, which has been accepted for publication in the journal The American Naturalist.
(Related photo: "Fooled Ants "Adopt" Rare Butterflies" [January 3, 2008].)
(Yanoviak's research was partially funded by the National Geographic Society's Committee for Research and Exploration. The National Geographic Society owns National Geographic News.)
Yanoviak's colleague Robert Dudley, a professor of integrative biology at the University of California, Berkeley, happened upon the infected tree-dwelling ants in Panama while studying their ability to glide.
Cephalotes atratus ants can make midair maneuvers, so that if knocked off a branch, they can steer toward the tree trunk, grab hold, and climb back up, the team showed in earlier work.
Dudley also noticed that some ants' gasters—the rear segments of their abdomens—were bright red. Yanoviak sliced open such a gaster in the lab and found it was full of the eggs of a parasitic nematode, or roundworm.
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