Effect of Endophytic Fungi on Herbivory by Redlegged Grasshoppers (Orthoptera: Acrididae) on Arizona Fescue

Abstract

We tested the hypothesis that an endophytic fungus, Acremonium starrii (White & Morgan–Jones), deters redlegged grasshoppers, Melanoplus femurrubrum (De Geer), from feeding on Arizona fescue, Festuca arizonica (Vasey), a native grass. Arizona fescue plants were screened and classified according to their level of endophyte infection. In the laboratory, we presented grasshoppers with grass clippings from plants of high or low endophyte infection levels either simultaneously (choice) or separately (no choice), and we measured the amount of each eaten by the grasshoppers. In the field, we monitored the mass of grasshoppers placed in cages built around plants of high or low levels of infection. In all cases, we found that grasshoppers consumed similar amounts of grasses with high and low infection levels, contrary to the prediction that endophytic fungi deter herbivores. Our results question whether the A. starrii endophyte alters the interactions of native populations of Arizona fescue with a native grasshopper.