The role of endophyte diversity in protecting plants from defoliation by leaf-cutting ants

Plants host a vast diversity of fungal symbionts inside their tissues that live in close proximity with each other to form rich and dynamic communities. Although endophytes can affect plant–herbivore interactions in several ways, it is still not known to what extent such effects are influenced by the properties of endophyte communities or by particular species traits. Here we compared the effects of high versus low foliar fungal endophyte diversity on the preferences of laboratory and wild colonies of leaf-cutting ants. We found that when endophyte densities were high, the ants responded similarly to leaves hosting one endophyte species, Colletotrichum tropicale, or those hosting a species-rich endophyte community. Results were also consistent when comparing the laboratory versus wild ant colonies. We discuss the significance of these results with respect to the ecological effects of plant–endophyte interactions in natural and agricultural ecosystems.