ABSTRACT
In aggregate, leaf-cutting ants are the most destructive herbivores in the New World tropics and subtropics. Our research group is investigating the host plant selection of the leaf-cutting ant Atta cephalotes in Costa Rica and searching for the reasons why some plant species escape attack. The mutualistic relationship between the leaf-cutters and their associated fungus opens intriguing questions in chemical ecology. Our group at Iowa consists of ecologists, chemists, and microbiologists working to characterize chemical defenses against leaf-cutting ants, discover the mechanisms by which they work, and understand their importance in host plant selection relative to other plant characteristics. Our search for the chemical factors affecting leaf-cutter choices required the development of a fast and reliable laboratory bioassay which we could use to quantify the activity of plant extracts or pure chemicals. Rapid and repeatable field bioassays were designed to investigate the palatability of plants and compare the preferences of different colonies.
