Achnatherum inebrians (drunken horse grass) causes symptoms in sheep and horses reminiscent of ergot alkaloid intoxication. Microscopical examination of seed and leaf tissues revealed the presence of an endophytic fungus that did not produce spores when grown in culture and which was serologically related to endophytic Acremonium species of the Albo-lanosa section Morgan-Jones & Gams. ELISA indicated the presence of high concentrations of ergot alkaloids. Ergonovine and lysergic acid amide were identified by HPLCat levels up to 2500 and 400 mg kg-1, respectivelyas the major ergot alkaloids by their retention times and their UV and fluorescence scans. Their identities were confirmed by HPLC analysis of epimerized extracts, and the identity of ergonovine was further confirmed by high-resolution FAB-MS and HPLC−FAB-MS. These are the highest levels of ergonovine and lysergic acid amide so far reported in an endophyte-infected grass, and the similarity of many of the symptoms of A. inebrians intoxication to those previously reported for ergonovine and lysergic acid amide implicates these alkaloids as causative agents of the toxicosis. Endophyte-free A. inebrians did not contain detectable levels of ergot alkaloids and may therefore be useful for stock fodder. A. inebrians was also examined for the presence of other alkaloids that are commonly found in endophyte−grass associations. N-Acetylloline and N-formylloline were not detected by GC, and peramine was not detected by HPLC, in endophyte-infected A. inebrians. However, ELISA and HPLC analyses were consistent with the presence of low levels of analogues of the indole−diterpenoids paxilline and lolitrem B. Keywords: Achnatherum inebrians; Stipa inebrians; Acremonium; endophyte; ergonovine; ergonovinine; lysergic acid amide; isolysergic acid amide

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Perennial ryegrass (Lolium perenne L.) is commonly infected with the endophytic fungus Acremonium lolii in a mutualistic relationship. The fungus produces a number of alkaloids, some of which are responsible for causing livestock disorders and/or for conferring insect resistance to the host grass. Little is known about the interrelationship between fungal growth and alkaloid production in the ryegrass plant and how this varies throughout the year. The concentrations of A. lolii and two of its alkaloid metabolites, lolitrem B and peramine, were monitored in basal (mainly leaf sheath) and upper (mainly leaf blade) parts of 17 endophyte-infected ryegrass plants on a monthly basis for 1 year. A. lolii, lolitrem B, and peramine concentrations were lowest in winter. The highest A. lolii concentrations were recorded in early summer, which coincided with the development of plant reproductive structures. Lolitrem B concentrations were highest from summer to early autumn and were consistently highest in the basal part of the plant. Peramine concentrations were generally highest in the upper part of the plant. Individual plants contained different levels of A. lolii, lolitrem B and peramine. These differences were generally maintained throughout the year. Although data for each month were variable, regression analyses showed that yearly mean concentrations of lolitrem B and peramine in individual plants were closely related to, and therefore probably largely determined by, yearly mean concentrations of A. lolii.

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Pasture mealybug (Balanococcuspoae) was found infesting two field trials evaluating the performance of selected strains of the endophyte Neotyphodium lolii in ryegrass (Lolium spp.) in Canterbury, New Zealand. Deterioration of endophyte-free plots relative to endophyte-infected plots had been observed. In Trial A, pasture mealybug were sampled in plots of the perennial ryegrass cultivar 'Grasslands Nui', without endophyte (nil), or infected with the wild-type endophyte, or the selected strains, AR1 and AR37. In Trial B, mealybug numbers on six ryegrass cultivars infected with AR1 or wild-type were compared with those on the same cultivars without endophyte. In sampling these trials, the presence of a root aphid, Aploneura lentisci, was also noted. Populations of mealybug in both trials were similar on all endophyte-infected treatments and significantly lower than populations on nil treatments. Neither AR1 nor wild-type appeared to reduce root aphid numbers, while AR37 may have had some effect. The amount of dead grass was significantly greater in nil than in endophyteinfected plots in Trial A, and yield of ryegrass was correlated with numbers of mealybug and root aphid present. Pasture productivity in nil treatments had recovered by spring, in the year of the outbreak. The presence of endophyte, strain of endophyte and cultivar were all significant factors affecting both total dry matter and green yield in Trial B. Pasture mealybug accounted for 55% of the variation in a decline in growth rate that occurred in this trial over the summer-autumn periods between 2000 and 2001, particularly in the nil treatments. Two years after the outbreak there was 25% less ryegrass and persistently lower pasture yields in nil plots. We conclude that pasture mealybug are capable of inflicting severe damage to endophyte-free ryegrass in Canterbury, particularly during dry summer-autumn periods.