http://www.digitaljournal.com/article/271167

Thriving Amazon Ant Colony Has No Males

Posted Apr 18, 2009 by Chris V. Thangham
A University of Arizona biologist has found a rare ant colony in the Amazon jungle with no males. The ants have virtually no sexual organs, but their colony thrives compared to other ant species.
Anna Himler, a University of Arizona biologist, and her team studied an ant species called Mycocepurus smithii. Many ant species keep domesticated “farms,” where they breed different types of fungus for food, but “Mycocepurus smithii” ants have far farms that are far more successful.
Himler found the farms of this particular ant variety contained more fungus and also more varieties of fungus than other ants.
Himler and her team wanted to find out what makes this particular ant species more successful than others. They found that there were no male ants and their sexual organs virtually disappeared. The ants reproduced by cloning.
They found fungus in the ant farms also reproduced by cloning.
Himler gave the following reasoning for this ant behavior. Himler told the BBC:
“It avoids the energetic cost of producing males, and doubles the number of reproductive females produced each generation from 50% to 100% of the offspring.”
All the ants in the colony were clones of the ant queen.
There are advantages and disadvantages with the all-female population; The advantages include being able to spend more time and energy to produce elaborate type of farms; the disadvantage is if the queen is responsible for cloning, she becomes vulnerable to pandemics and the entire colony becomes vulnerable because they can inheret the same immune system.
Himler said she has seen many ant varieties that have unusual reproductive strategies but the “Mycocepurus smithii” ants are very rare in nature.