Invertebrate diversity on sleepy grass (Achnatherum robustum) infected with the alkaloid-producing Neotyphodium endophyte

Abstract

Sleepy grass is a native grass of the southwestern United States that is inhabited by a symbiotic fungal endophyte of the genus Neotyphodium. Endophytes, by definition, are fungi that reside entirely within the tissues of their host plant throughout most of their life cycle. It has been proposed that the ancestors of endophytes were pathogenic fungi that developed specialized relationships with their host plants. The relationship between Neotyphodium and its host grasses is thought to be mutualistic. The endophyte produces several types of noxious alkaloids that are known to cause toxicosis in vertebrate herbivores such as cattle. In fact, plants infected with the endophyte are avoided by some vertebrate herbivores. In this investigation, it was hypothesized that the alkaloid levels produced by a plant’s endophytic fungi result in a change in community composition on the plant.