Ant Body Odor Signals Job To Be Done

April 27, 2004 Dig, look for food, gather food, dig, dig, gather food, care for young, dig, look for food: there is so much work to be done in an ant colony! With so much to do, how does an ant know what job to perform? When researchers Drs. Michael Greene and Deborah Gordon studied the ants, they found a surprising answer: ANT BODY ODOR! The Stanford University researchers studied red harvester ants. These desert-dwelling, seed-eating ants have a single queen and live in colonies with 10,000 to 12,000 workers. If patroller ants do not return to the nest, forager ants that gather food will stay in the nest. To study how patroller ants communicate with forager ants, the researchers created a "fake ant." The fake ant was made of a small glass bead that was coated with the smell of a patroller ant and then placed just inside the entrance of the nest. If the time of day was right, the coated glass beads could trick the forager ants into leaving the nest just as often as real live patroller ants. Only patroller ant body odor worked; beads coated with the smell of nest maintenance ants had little effect on the forager ants. Drs. Greene and Gordon believe that ants that spend time outside the nest in a warm, dry environment have a unique body odor. When ants in the nest smell this odor on returning ants, they can change jobs to leave the nest and find food. So, if the time and smell is right, it's a signal to go outside to gather up dinner. These chemical signals, therefore, can influence the behavior of individual ants and the entire ant colony.