ABSTRACT
Richardson (2000) briefly catalogs the history of endophyte research in grasses, showing that the effect of infected plants on grazing animals has been noted since the early 1980s. He continues to discuss the importance of the production of alkaloids by these endophytic fungi as being the causal agent of herbivore avoidance. These alkaloids are secondary metabolites of the fungi and are considered to have evolved as an adaptation to confer competitive advantage to the endophyteinfected host plant. Indeed, Lane et al. (2000) show that the infection of grasses with asexual Neotyphodium endophyte exerts a natural selection in favor of the host plant, increasing its fitness in competition with other plant species due to antiherbivore and plant-growth-promoting factors. It would appear that the degree of protection afforded to a host plant by an endophyte does not change under changing environmental conditions. In a study of the influence of elevated carbon dioxide on the rate of grazing of grasses by the fall armyworm Spodoptera frugiperda, Marks and Lincoln (1996) saw an increase in grazing intensity with elevated CO2, but the proportion of plant consumed by the insects was similar to that of plants grown in ambient conditions (Fig. 5.15). Indeed, Clay (1997) showed that endophyte-infected plants outperformed uninfected plants in the presence of herbivory and suggested that the evolutionary trajectory of increasing endophyte infection of plants will be associated with the level of herbivory (Fig. 5.16). Use of fungal endophytes for pest management is appearing as a new science. Prestidge and Ball (1997) cite evidence of the adverse effects of Acremonium-infected tall fescue on 12 species of beetle, two species of flies, 16 species of Hemiptera and Homoptera, and eight species of lepidopteran larvae, thus suggesting that endophytes could be important biological control agents of agricultural pests.
