The occurrence of the alkaloidsN-formyl andN-acetyl loline, peramine, lolitrem B, and ergovaline and the response of aphids to plants containing these compounds were determined in species and cultivars ofFestuca,Lolium, and other grass genera infected with fungal endophytes (Acremonium spp., andEpichloe typhina). Twenty-nine of 34 host-fungus associations produced one or more of the alkaloids, most frequently peramine or ergovaline. Three alkaloids (lolines, peramine, and ergovaline) were found in tall fescue and in perennial ryegrass infected withA. coenophialum, while peramine, lolitrem B, and ergovaline were present in perennial ryegrass and in tall fescue infected withA. lolii and inF. longifolia infected withE. typhina. WhileA. coenophialum andA. lolii produced similar patterns of alkaloids regardless of the species or cultivar of grass they infected, isolates ofE. typhina produced either no alkaloids or only one or two different alkaloids in the grasses tested. Aphid bioassays indicated thatRhopalosiphum padi andSchizaphis graminum did not survive on grasses containing loline alkaloids and thatS. graminum did not survive on peramine-containing grasses. Ergovaline-containing grasses did not affect either aphid.

INTRODUCTIONThe tenn endophyte (Greek: endo == within + phyte = plant) has been defined as an organism contained or growing (entirely) within the substrate plant, whether parasitically or not (100, 106). Using this tenn in its broadest sense, the subject of this chapter could include all fungi that spend all or nearly all of their life cycles in the host grasses. We do not discuss such endophytic fungi as the smuts and vesicular-arbuscular mycorrhizas that infect grass. Instead, our interests lie primarily with a specific group of c1avicipitaceous fungi that belong or are related to fungi in the tribe Balansiae (5, 24). These fungi either are true endophytes that never produce external fructifications on the plant or else may produce external mycelium andlor spores that affect flower and seed production. We focus specifically on those grass-endophyte complexes that may also cause maladies of grazing animals.Using the above criteria, two recent events involving grass-endophyte associations have important implications for the livestock industry. In 1977 Bacon et al (9) reported the close association of an endophyte (Sphacelia typhina) in infected tall fescue (Festuca arundinacea) and the incidence of 293 0066-4286/87/090 1-0293$02.00Annu. Rev. Phytopathol. 1987.25:293-315. Downloaded from www.annualreviews.org by ILLINOIS STATE UNIVERSITY on 10/24/12. For personal use only. Quick links to online content Further ANNUAL REVIEWS 294 SIEGEL, LATCH & JOHNSON fescue toxicosis (summer syndrome) in cattle. A similar association between a then unidentified endophyte in perennial ryegrass (Latium perenne) and the incidence of ryegrass staggers in sheep in New Zealand was reported in 1981 by Fletcher & Harvey (27). Since the initial work of Bacon et al (9) in 1977, researchers have come to further understand the relationship between fungal endophytes of grasses and animal toxicoses. This understanding includes the origin and incidence of infected grasses, modes of dissemination of the fungi, identification of the chemicals responsible for toxicoses, and control of the fungi. Specifically, what has been learned is that endophyte-infected tall fescue and perennial ryegrass are widely distributed in the United States and New Zealand, respec tively; endophytic fungi are only seed disseminated; specific chemicals are responsible for fescue toxicosis and ryegrass staggers; infected pasture grasses cost the livestock producer hundreds of millions of US dollars annually in lost production; the fungi cannot be controlled in the field, but endophyte-free cultivars do result in greatly improved livestock production in the United States; and lastly, the relationship between grass and symbiont is primarily mutualistic. resulting in many benefits to host and fungus (5, 10, 97). With regard to this final point, it is now recognized that these grass endophytes can play an important role in survival of the host plants subjected to environmen tal stresses (insects, grazing animals, drought, and heat). The potential for improved insect resist...

Documenting whether a biotic taxon is native or alien to an ecosystem has theoretical value for ecological and evolutionary studies, and has practical value because it can potentially identify a taxon as a desirable component of an ecosystem or target it for removal. In some cases, however, such background information is inadequate or unavailable. Here we use paleo-DNA to re-evaluate the historical status of yellow perch in the 6 million acre Adirondack State Park of northern New York. Yellow perch DNA in a 2200-year sediment record reveals a long-term native status for these supposedly alien fish and challenges assumptions that they necessarily exclude native trout from upland lakes. Similar approaches could be applied to other species with uncertain historical distributions and could help to identify unrecognized pockets of biodiversity.

The presence of an endophytic fungus, Acremonium coenophialum , in tall fescue ( Festuca arundinacea ) deterred aphid feeding by Rhopalosiphum padi and Schizaphis graminum. Both species of aphid were unable to survive when confined to endophyte-infected tall fescue plants. Feeding deterrents and toxic factors to R. padi and Oncopeltus fasciatus , large milkweed bug, were primarily associated with a methanol extract obtained when endophyte-infected tall fescue seed was serially extracted with hexane, ethyl acetate, and methanol. The concentrations of pyrrolizidine alkaloids were determined to be 30 to 100 times greater in the methanol extract than in the hexane and ethyl acetate extracts.

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