Sucrose-Free Sips Suit Acacia Ants

摘要

The thorny acacia tree has strong allies: vicious, centimeter-long ants whose nasty bite scares off plant-eating animals and also humans. In return for defending acacias, the ants get free meals and places to live. The key to this sweet deal is the sucrose-free nectar provided by the plant, says Martin Heil, an ecolo- gist at the Max Planck Institute for Chemical Ecology in Jena, Germany. As he and his colleagues report on page 560, a sucrose-degrading enzyme produced by the acacia customizes its nectar to appeal to the right ant partners. The defensive-minded ants that protect the tree prefer their nectar without sucrose, while other ants do not, the researchers found.