Toxicity of terpenoid deterrents to the leafcutting antAtta cephalotes and its mutualistic fungus.

Four natural products, of varying activity as deterrents of leafcutter attack, were tested for their effects on ant survival and on the growth of the mutualistic attine fungus. The substances were incorporated into an artificial liquid diet for bioassays on the ants or included in an agar culture medium for fungus growth-inhibition studies. Three of the four compounds exhibited deleterious effects on either adult leafcutting ants or their mutualistic fungus, and there appeared to be some correlation between deterrency and activity in these toxicity assays. The implications of these findings for leafcutting ant foraging patterns are discussed.