Musgrave, D.R.Ball, Olivier2026-09-142026-09-141994https://hdl.handle.net/10289/18641Three broad, but related, categories of research were undertaken in this study. The first involved developing an enzyme-linked immunosorbent assay (ELISA) to quantify Acremonium lolii levels in perennial ryegrass. The second was aimed at investigating how concentrations of the alkaloids peramine and lolitrem B (measured using high performance liquid chromatography) and of A. lolii (measured using the ELISA), varied with factors such as plant/endophyte genotypes, season, plant component, plant age and plant management. The third was aimed at investigating the effect of endophyte-infection on adult black beetle, and once an effect had been established, the chemical mechanism of the resistance. 1. A quantitative ELISA to A. lolii was developed by inoculating rabbits with either the mycelial antigen fraction or the soluble antigen fraction of A. lolii. Both antigen types were effective in eliciting immune responses, and it was found that using two different antibodies in the assay, one derived from a rabbit injected with the mycelial antigen, the other derived from a rabbit injected with the soluble antigen, greatly enhanced detection of the endophyte. It was also found that grass samples had to be freeze-dried rather than oven-dried before detection of A. lolii was possible. 2. A. lolii, peramine and lolitrem B concentrations were lowest in winter. The increase in A. lolii content appeared to be correlated with reproductive development of the ryegrass host. Peramine and lolitrem B concentrations in the plants were largely determined by the concentration of A. lolii. Peramine concentrations increased, and lolitrem B concentrations decreased as leaf age decreased. Also, lolitrem B and A. lolii concentrations were generally higher in leaf sheaths compared to leaf blades. Peramine was distributed more evenly between the leaf sheath and leaf blade. Compared to all other plant components A. lolii, peramine and lolitrem B concentrations were highest in the seed. A. lolii growth in plants which were not regularly trimmed and therefore allowed to become reproductive, was significantly enhanced compared to the growth of A. lolii in trimmed plants. The opposite was true of peramine concentrations early in the reproductive phase of rye grass. The significance of these results, and those of an experiment investigating the effect of plant age on alkaloid concentration, from the perspectives of the plant, insect pests and livestock are discussed. 3. Adult black beetle was found to be deterred from feeding by the presence of Acremonium endophytes in perennial ryegrass. Peramine, lolitrem B and paxilline did not deter adult black beetle from feeding on artificial diet discs. Ergotamine significantly deterred black beetle from feeding on artificial diets at a concentration of 5 μg/g or more. Choice tests using ryegrass plants infected with Acremonium endophytes producing different alkaloid spectra, confirmed that peramine and lolitrem B were not required for adult black beetle resistance. Ergovaline was also not necessary for adult black beetle resistance. The significance of these results with regard to using endophytic fungi as biocontrol agents of black beetle is discussed.enAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.Thesis