Airdate: Aug 23, 2004
Scientist: Diane Wagner
Ants & Caterpillars: Interdependence
Did you ever consider an ant to be the perfect baby-sitter?
ambience: dawn at desert
This time of year, heavy monsoon rains saturate the dry soil of Arizonaâ€™s Sonoran Desert. The acacia shrubs are in bloom, and their nectar attracts colonies of ants to nest at their base. The acacia flowers also attract butterflies, and the ants and butterflies have evolved a remarkable interdependent relationship. I'm Jim Metzner, and this is the Pulse of the Planet. Diane Wagner is an assistant professor in the Department of Biological Sciences at the University of Nevada.
â€œAfter the monsoon rains the butterflies arrive. And the butterfly Iâ€™m talking about is the Reichertâ€™s Blue, and this is a small, dime-sized butterfly. And the juvenile stages of the butterfly are tended by ants, the way you mightâ€™ve seen ants tending aphids or treehoppers.â€
Well, some species of ants are known to tend herds of aphids like cattle, feeding on the aphidsâ€™ secretions and in return, protecting them from predators. Well, in the same way, these Sonoran Desert ants tend the caterpillars - the larvae of the Reakirtâ€™s blue butterflies.
â€œThe ant stands on the caterpillar, and it touches it with its antennae, and it touches it in ways that tell the caterpillar to secrete a droplet of food. So the ant can feed from the caterpillar, from a gland on the caterpillarâ€™s back and in return, if a predator approaches the caterpillar, the ant will chase it off. So the ants provide protection to the caterpillars and the caterpillars feed the ants in return.â€
This relationship only lasts during the juvenile stage of the caterpillarâ€™s life. Once itâ€™s transformed into a butterfly, it has but a few moments to fly away, otherwise the ants will kill it.
Pulse of the Planet is presented with support provided by the National Science Foundation.