But in a new study, Rissing and his colleagues found some genetically odd colonies of harvester ants (Pogonomyrmex), that don't seem to abide by the traditional rules of caste development. They found that genetics not environment determines the fate of a developing ant, and consequently the role it will play in the colony.
The researchers report their findings in the latest issue of the journal Current Biology. The team was led by Sara Helms Cahan, an assistant professor of biology at the University of Vermont.
A typical ant colony includes one queen and, in the case of harvester ants, hundreds or thousands of sterile female workers (worker ants are always female and, with a few exceptions, sterile. Soldier ants are larger versions of workers.) During her lifetime, which can last as long as 20 or 30 years, a queen produces mainly worker eggs.
Male ants, which come from unfertilized eggs, typically serve one purpose: to mate with a queen. Males are usually in short supply, and a queen produces male eggs only when it's time to make more colonies. Then a queen produces eggs that give rise to both males and queens (reproductive females). The males and new queens swarm out of the nest, mate, and the young queens try to establish a new a colony. Males, which have short life spans, die shortly after mating.
The type of ants in this study harvester ants are one of the largest insect societies in the western United States, with ranges covering hundreds of miles and nests so large they're visible from airplanes.
"This is the ant that runs the west it's everywhere," Rissing said.
Contact: Steve Rissing
Rissing.2@osu.edu
614-688-4989
Ohio State University
11-Jan-2005