A fungal endosymbiont of the grass Bromus setifolius: Distribution in someAndean populations, identification, and examination of beneficial properties

Endophyte infection levels were estimated in populations of the grass Bromu s setifolius at several sites in the Andes Mountains in South America. The endophyte was identified as pertaining to the Neotyphodium tembladerae clad e using sequence data. A high percentage of grass individuals infected by t he endophyte was found in populations located in communities that contained leaf-cutting ants (Acromyrmex sp.). N. tembladerae was found to produce tw o mycotoxins (ergovaline and peramine) that are known to be toxic to insect herbivores. Feeding experiments demonstrated that fall armyworms preferred endophyte-free B. setifolius over endophyte-infected B. setifolius when gi ven the option of both. The results of this investigation support the defen sive mutualism hypothesis that defense of the host from herbivores is a bas is for the mutualistic association between clavicipitaceous endosymbionts a nd host grasses.