Research: Leaf-cutting ants do not harvest coffee leaves in shade farms
Varon, E. H., S. D. Eigenbrode, N. A. Bosque-Perez, and L. Hilje. 2007. Effect of farm diversity on harvesting of coffee leaves by the leaf-cutting ant Atta cephalotes. Agriculture and Forest Entomology 9:47-55. Leaf-cutting ants, which are common in the tropics, cut pieces of live leaves and carry them to underground burrows where they are used to raise a fungus, which is the food of the ants.
The types of leaves these ants harvested were studied on Costa Rican coffee farms which varied in the diversity of tree species present. In sun coffee monocultures, the proportion of coffee leaves harvested was highest, at 40% of total biomass. It was under 1% in farms with complex shade, and the ants preferred shade tree species over coffee when given the choice in trials.
Leaf-cutting ants can consume 12 to 17% of leaf production in an area,and can defoliate coffee plants if there are not preferred alternatives. Damage to coffee plants by these ants is minimized by the availability of a diversity of shade trees.
Photo of Atta cephalotes by Scott Bauer. USDA Agricultural Research Service.