scholarly journals Olfactory responses of Argentine stem weevil to herbivory and endophyte-colonisation in perennial ryegrass

2021 ◽  
Author(s):  
Louise M. Hennessy ◽  
Alison J. Popay ◽  
Travis R. Glare ◽  
Sarah C. Finch ◽  
Vanessa M. Cave ◽  
...  
Keyword(s):  
Volatile Compounds ◽  
Perennial Ryegrass ◽  
Fungal Endophytes ◽  
Fungal Endophyte ◽  
Wild Type ◽  
Olfactory Responses ◽  
Plant Volatile ◽  
Endophyte Infection ◽  
Listronotus Bonariensis ◽  
Volatile Blend

AbstractArgentine stem weevil adults (ASW, Listronotus bonariensis) feed on the leaves of agricultural grasses and their larvae mine the pseudostem, causing extensive damage that can result in plant death. Plants emit volatiles that serve as signals to host-searching insects and these odours can be altered by both herbivory and fungal endophyte-infection. This study investigated whether ASW adults utilise olfaction to identify their host plants, perennial ryegrass (Lolium perenne), and if conspecific herbivory or the presence of Epichloë festucae var. lolii fungal endophytes (strain wild-type or AR1) influenced such responses. Results from olfactometer bioassays established that ASW adults were able to utilise their olfactory response to orient towards volatiles released by perennial ryegrass and further, the weevils displayed a preference for plants previously damaged by conspecific weevils. However, there was no evidence that weevils had the ability to distinguish between endophyte-infected and endophyte-free plants using olfaction alone. Using a push–pull extraction technique, thirteen volatile compounds were identified in the blend released by perennial ryegrass. Endophyte and herbivory were found to alter these volatile compounds and quantities emitted by this forage grass. This study suggests that despite observing differences in the plant volatile blend, ASW do not perceive endophyte (wild-type and AR1) using olfaction alone and must rely on other cues, e.g. contact chemoreception or post-ingestional malaise, to detect the presence of a bioactive endophyte in an otherwise acceptable host plant.

scholarly journals Ryegrass production in Wairarapa, New Zealand: is biological control of Argentine stem weevil important?

2007 ◽  
Vol 13 ◽  
pp. 301-306
Author(s):  
M.R. Mcneill ◽  
D.E. Hume ◽  
R. Ashby ◽  
M. Ashby ◽  
P. Brandon ◽  
...  
Keyword(s):  
Lolium Perenne ◽  
Dry Matter ◽  
Fungal Endophyte ◽  
Wild Type ◽  
Neotyphodium Lolii ◽  
Endophyte Infection ◽  
Plant Persistence ◽  
Listronotus Bonariensis ◽  
Microctonus Hyperodae ◽  
Over Time

To investigate the interaction between Argentine stem weevil (Listronotus bonariensis), its parasitoid Microctonus hyperodae, fungal endophyte (Neotyphodium lolii) and its grass host, four endophyte-ryegrass (Lolium perenne) treatments were established on four farms in Wairarapa in autumn 2003. A diploid ryegrass contained either wild-type or AR1 endophyte or was endophytefree, while a tetraploid ryegrass contained AR1 endophyte. Wild-type, AR1 and endophyte-free ryegrasses average 52%, 91% and 2% endophyte-infected tillers for the 3 years of measurement. Moderate increases over time in the proportion of wild-type infected tillers indicated selection pressures favoured endophyte-infected tillers. Endophyte-free tiller populations were 11% lower than AR1 or wild-type but not significantly so. L. bonariensis populations were highest in endophyte-free and wild-type pastures and 80% lower in AR1 pastures. Mean rates of parasitism in L. bonariensis were lower in spring (9%) than autumn (35%), tended to be higher in wild-type than in AR1 diploid ryegrass, and only had a weak relationship with percent endophyte-infection. Keywords: endophyte, Neotyphodium lolii, Lolium perenne, dry matter yields, plant persistence, Listronotus bonariensis, Microctonus hyperodae

Fungal endophytes of Festuca rubra increase in frequency following long-term exclusion of rabbits

Botany ◽  
2015 ◽  
Vol 93 (4) ◽  
pp. 233-241 ◽  
Author(s):  
James S. Santangelo ◽  
Nash E. Turley ◽  
Marc T.J. Johnson
Keyword(s):  
Plant Growth ◽  
Intraspecific Competition ◽  
Fungal Endophytes ◽  
Natural Populations ◽  
Fungal Endophyte ◽  
Festuca Rubra ◽  
Red Fescue ◽  
Grass Endophyte ◽  
Defensive Mutualism ◽  
Endophyte Infection

Plant – fungal endophyte interactions are common in nature and they can shape the ecology of plants. Vertically transmitted endophytes are hypothesized to serve as mutualists, protecting plants from herbivores. If this hypothesis is true, then we expect endophytes to be most abundant in the presence of herbivores and least abundant in their absence, assuming endophytes incur a cost to their host. We tested this prediction by studying the effects of intense rabbit (Oryctolagus cuniculus Linnaeus) grazing on grass–endophyte interactions at Silwood Park, UK. We examined seeds of red fescue (Festuca rubra L.) collected from 15 natural populations that were protected from rabbits for 0.3–21 years. Contrary to our prediction, the mean proportion of seeds with endophytes increased 1.84×, from 0.45 to 0.83, following 21 years of rabbit exclusion. To better understand the mechanisms driving this increase in frequency, we conducted a fully factorial greenhouse experiment where we manipulated the presence or absence of endophyte infection, intraspecific competition, and simulated grazing on F. rubra plants. In both damaged and undamaged treatments, infected plants produced approximately twice as much biomass as uninfected plants, and endophytes did not influence tolerance to herbivory. These results suggest that endophytes directly change plant growth but not compensatory responses to damage. In the absence of competitors, infected plants produced 2.17× more biomass than uninfected plants, whereas in the presence of competitors, infected plants produced only 1.55× more biomass than uninfected plants. This difference suggests that intraspecific competition might lessen the benefits of endophyte infection. Our results do not support the defensive mutualism hypothesis, but instead suggest that endophyte-induced plant growth is important in shaping the costs and benefits of endophytes in our system.

scholarly journals Evaluation of several lolitrem-free endophyte/perennial ryegrass combinations

1991 ◽  
pp. 215-219 ◽  
Author(s):  
L.R. Fletcher ◽  
A.J. Popay ◽  
B.A. Tapper
Keyword(s):  
Weight Loss ◽  
Perennial Ryegrass ◽  
Fungal Endophyte ◽  
Feeding Deterrent ◽  
Animal Performance ◽  
Wild Type ◽  
Affected Animal ◽  
Lolitrem B

The fungal endophyte Acremonium lolii, in association with its ryegrass host, produces both peramine, a feeding deterrent to Argentine stem weevil,andlolitrem B,a neurotoxin causing ryegrass staggers. Endophyte strains vary in the ratio of production of these alkaloids in the ryegrass. In field evaluations of several endophyte/ryegrass - combinations, 'Endosafe', a zero lolitrem B, high peramine strain protected its host against Argentine stem weevil attack and did not cause ryegrass staggers in lambs grazing three of four ryegrass cultivars. Lambs on the endophyte-free and Endosafe combinations had the highest liveweight gains and while endophyte-free ryegrass did not cause ryegrass staggers it suffered significant stem weevil damage. Ryegrasses with their 'wild-type' endophyte and a high lolitrem B strain 'Waiau', had only minor stem weevil damage but caused severe ryegrass staggers and weight loss in lambs. Ryegrass with the no lolitrem B, low peramine strain, 'IOOA', suffered some stem weevil damage and although not causing ryegrass staggers, did cause weight loss in lambs. Ryegrass/endophyte metabolites in addition to lolitrem B may have affected animal performance on endophyte-infected ryegrass. Keywords endophytc, Endosafe, perennial ryegrass,ryegrass staggers, Argentine stem weevil, liveweight gains, peramine, lolitrem B

scholarly journals Black beetle damage to perennial ryegrass infected with AR1 endophyte

2001 ◽  
pp. 267-271 ◽  
Author(s):  
A.J. Popay ◽  
J.G. Baltus
Keyword(s):  
New Zealand ◽  
Perennial Ryegrass ◽  
Field Trials ◽  
Fungal Endophyte ◽  
Reproductive Capacity ◽  
Wild Type ◽  
Adult Feeding ◽  
Important Pest ◽  
Pot Trial ◽  
Beetle Damage

AR1 is a new fungal endophyte that is being released in perennial ryegrass to New Zealand farmers. This endophyte lacks the mammalian toxins, ergovaline and lolitrem B, but produces peramine which provides resistance to a major ryegrass pest, Argentine stem weevil (Listronotus bonariensis). Black beetle (Heteronychus arator) is another important pest of ryegrass in northern areas of New Zealand. Adults are selective feeders, and avoid feeding on ryegrass infected with wildtype endophyte. A limited supply of suitable food greatly reduces their reproductive capacity. Laboratory and field investigations were therefore carried out to evaluate the degree of resistance to black beetle provided by AR1. Assessments of adult black beetle feeding were made on two field trials planted in autumn 1999. In both trials, adult feeding was significantly higher on ryegrass infected with AR1 than on ryegrass with wild-type but also significantly lower on AR1 than on endophyte-free ryegrass. In a pot trial conducted in summer, black beetle adult damage to 4-week-old AR1-infected ryegrass was no different from damage to endophyte-free plants. However in 6-month-old plants, damage to AR1 plants was significantly less than to endophyte-free plants and was similar to damage levels on wild-type plants. A further pot trial showed that beetles overwintering on AR1 ryegrass had a higher reproductive capacity than those overwintering on wild-type infected ryegrass. In February 2001, two field trials planted the previous June were sampled for black beetle larvae. Black beetle presence was significantly higher on endophyte-free plots than on wild-type plots, with presence on AR1 intermediate between these treatments. Ryegrass infected with AR1, although showing a degree of resistance to black beetle compared with endophyte-free ryegrass, is more susceptible to damage than wild-type, particularly in its first year of planting. Limited data indicate that older AR1 swards may have similar resistance to that of the wild-type but further research is needed to clarify the effect of stand maturity on black beetle damage to ryegrass infected with this new endophyte. Keywords: AR1, black beetle, endophyte, Heteronychus, Listronotus, Neotyphodium, ryegrass

scholarly journals Establishing and maintaining a toxin-free pasture: a review

1999 ◽  
Vol 7 ◽  
pp. 123-132
Author(s):  
D.E. Hume
Keyword(s):  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Tall Fescue ◽  
Fungal Endophytes ◽  
Wild Type ◽  
Neotyphodium Lolii ◽  
Domestic Livestock ◽  
Buried Seed ◽  
On Farm ◽  
Sources Of Contamination

This paper reviews how new pastures may become contaminated with perennial ryegrass (Lolium perenne) infected with wild-type fungal endophytes (Neotyphodium lolii). These wild-type endophyte strains may be toxic to domestic livestock. Sources are from seed (natural reseeding, buried seed, sown seed, in dung, hay, carried on farm machinery) and survival of existing infected ryegrass plants. In particular, seed in soil and dung are reviewed. Contamination may occur both pre- and postestablishment. It is recommended that steps should be taken to minimise contamination from all sources when establishing new pastures. Although normal establishment practices for successful rapid establishment of weed-free pastures (e.g., cropping, fallow, herbicides) will minimise the risk of contamination, a number of cases highlight that extra time (e.g., 18-24 months planning rather 6- 12 months) and consideration of all sources of contamination is needed to minimise risk. Once established, further measures should be taken to prevent seed being transferred in dung or hay. This has implications when establishing pastures with endophyte-free ryegrasses, ryegrasses with selected non-toxic endophytes, a new ryegrass cultivar, or other grasses (e.g., tall fescue), whether for grazing by animals or for seed production. Keywords: endophyte, endophyte survival, faeces, Lolium perenne, natural reseeding, Neotyphodium lolii, pasture establishment, perennial ryegrass, seed burial, seed survival, tall fescue

Host plant genetics affect hidden ecological players: links among Populus, condensed tannins, and fungal endophyte infection

2005 ◽  
Vol 83 (4) ◽  
pp. 356-361 ◽  
Author(s):  
Joseph K Bailey ◽  
Ron Deckert ◽  
Jennifer A Schweitzer ◽  
Brian J Rehill ◽  
Richard L Lindroth ◽  
...  
Keyword(s):  
Host Plant ◽  
Genetic Markers ◽  
Condensed Tannin ◽  
Fungal Endophytes ◽  
Fungal Endophyte ◽  
Ecological Genetics ◽  
Plant Genetics ◽  
Endophyte Infection ◽  
Bark Tissue ◽  
Tannin Concentration

Recent studies have shown effects of host plant genetics on community and ecosystem processes, which makes understanding the impacts of genetically based traits on hidden or non-apparent organisms more important. Here we examined links among genetic variation in hybrid cottonwoods, plant phytochemistry, and twig fungal endophytes (i.e., a common hidden organism). We found three major patterns: (1) twig fungal endophyte infection was positively related to the introgression of Fremont cottonwood (Populus fremontii S. Wats.) RFLP genetic markers, (2) condensed tannin concentration in twig bark tissue was negatively correlated to the introgression of Fremont genetic markers, and (3) fungal endophyte infection was negatively related to condensed tannin concentration in twig bark. These data demonstrate that plant genotype can impact hidden ecological players (i.e., fungal endophytes) resulting in community and ecosystem consequences.Key words: ecological genetics, fungal endophytes, hidden players, hybridization, Populus, tannins.

scholarly journals Ryegrass endophyte infection affects Argentine stem weevil adult behaviour and susceptibility to parasitism

2000 ◽  
Vol 53 ◽  
pp. 406-409 ◽  
Author(s):  
P.J. Gerard
Keyword(s):  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Neotyphodium Lolii ◽  
Pot Experiments ◽  
Endophyte Infection ◽  
Listronotus Bonariensis ◽  
Microctonus Hyperodae ◽  
Observation Period

Pot experiments were undertaken to investigate whether Argentine stem weevil Listronotus bonariensis adults placed on endophyteinfected or endophytefree perennial ryegrass (Lolium perenne) exhibited behaviour differences that may lead to differing susceptibility to attack by the endoparasitoid Microctonus hyperodae There was no difference (P>005) in the behaviour of weevils on pots of Nui ryegrass infected with either the wildtype endophyte Neotyphodium lolii or AR1 a N lolii selection high in peramine but low in other key alkaloids Although adults were offered no choice over 60 of the adults were found off endophyteinfected plants during the observation period Weevils on high endophyte plants were found to spend less time in positions highly favourable for parasitoid oviposition (eg feeding P

scholarly journals Field performance of perennial ryegrass (Lolium oerenne) infected with toxin-free fungal endophytes (Neotyphodium spp.)

1999 ◽  
Vol 7 ◽  
pp. 113-122
Author(s):  
A.J. Popay ◽  
D.E. Hume ◽  
J.G. Baltus ◽  
G.C.M. Latch ◽  
B.A. Tapper ◽  
...  
Keyword(s):  
Insect Resistance ◽  
Perennial Ryegrass ◽  
Fungal Endophytes ◽  
Field Performance ◽  
Insect Damage ◽  
Wild Type ◽  
Pasture Production ◽  
Adult Feeding ◽  
Lolitrem B ◽  
Beetle Damage

A national series of six small plot trials were sown in 1996 and four in 1997 to evaluate the performance of six novel fungal endophytes in Grasslands Nui perennial ryegrass. These endophytes do not produce the mammalian toxins, ergovaline and lolitrem B, but produce peramine, a feeding deterrent to the major ryegrass pest, Argentine stem weevil (ASW). Trials included the naturally occurring endophyte (wild-type) which produces both toxins, and an endophyte-free (nil) treatment. Pasture production was measured regularly and samples were taken at least once each summer-autumn from all trials for assessment of ASW damage. Black beetle larval damage was recorded on three trials. The toxin-free endophytes, AR1, AR12, AR22 and the wild-type were equally effective at reducing ASW adult feeding and larval damage significantly below that which occurred in nil treatments. Ryegrass infected with AR1, AR12, AR22 and the wild-type endophyte was damaged less by black beetle larvae than ryegrass without endophyte. The effect of AR24 on insect damage was variable and two other toxin-free endophytes, AR17 and AR506, which had low infection rates, seldom reduced either ASW or black beetle damage. Yield differences between treatments were found on two of 21 sampling occasions between October and December and 12 of 30 sampling occasions between January and April. During summer-autumn, wild-type, AR1, AR12 and AR22 gave higher ryegrass yields than the nil, AR17 and AR506 treatments. In the second year of the 1996-sown trials, productivity of ryegrass with AR1 in the summer-autumn tended to be lower than that of the wild-type with significant differences occasionally occurring. Yield differences were correlated with either ASW or black beetle damage in North Island trials and with percent endophyte infection at all sites. Differences in yield at Lincoln, Canterbury, were attributed to pasture mealy bug. Three conclusions were drawn from these results: 1. Endophytes are very important for maximising ryegrass yield during summer and early autumn. 2. The effect of endophytes on yield is at least partly due to the insect resistance they impart. 3. The field performance of three toxin-free endophytes, AR1, AR12 and AR22, equalled that of the wild-type in terms of increased insect resistance but did not always match it in plant growth. Keywords: AR1, Argentine stem weevil, black beetle, endophyte strain, ergovaline, insect damage, lolitrem B, Neotyphodium lolii, ryegrass yield

scholarly journals Endophyte fungus levels in perennial ryegrass and tall fescuse varieties grown for seed in Oregon, USA - implications for responsible grass straw use as livestock feed

2007 ◽  
Vol 13 ◽  
pp. 275-276
Author(s):  
Young Iii ◽  
M.E. Mellbye ◽  
T.B. Silberstein ◽  
G.A. Gingrich ◽  
A.M. Craig ◽  
...  
Keyword(s):  
Perennial Ryegrass ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Fungal Endophyte ◽  
Infection Level ◽  
Grass Seed ◽  
Seed Industry ◽  
Livestock Feed ◽  
Endophyte Infection ◽  
Seed Harvest

Baling of perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) straw residue following seed harvest has become a common practice in Oregon's grass seed industry. In 2005, almost 670 000 tons [607 000 Mg (tonne)] of grass straw was exported to Japan and Korea for use as livestock feed. Most of the grass seed varieties grown today are turf-type, which in recent years have been developed with high levels of fungal endophyte infection. Currently, over 73% and 43% of perennial ryegrass and tall fescue varieties, respectively, are ranked as having a "High" (>61% infected) infection level. Concern for the safe use of these grass straw residues had led to their routine analysis for toxin content before shipment to consuming markets. These chemical analyses provide assurances against deleterious effects to livestock fed Oregon grass straw. Keywords: straw, endophyte-infected, perennial ryegrass, tall fescue

scholarly journals Spontaneous in planta changes in fungal endophytes impact symbiosis

2007 ◽  
Vol 13 ◽  
pp. 191-193
Author(s):  
W.R. Simpson ◽  
M.J. Christensen ◽  
R.D. Johnson ◽  
J. Schmid
Keyword(s):  
Perennial Ryegrass ◽  
Cell Walls ◽  
Fungal Endophytes ◽  
Fungal Mycelium ◽  
Wild Type ◽  
In Planta ◽  
Neotyphodium Lolii ◽  
The Relationship ◽  
Host Tissues

The symbiosis between the asexual Ascomycetous fungi of the genus Neotyphodium and host grasses is considered to be symptomless. Symbioses involving Epichloë can show symptoms but this is restricted to the formation of stroma on floral structures. Fungal mycelium of both Epichloë and Neotyphodium endophytes occupy the intercellular space of plant tissues with no breach of host cell walls. Research involving these endophytes and their host grass symbioses relies on staining of host tissues and microscopic examination, immuno-detection or in-vitro isolation to determine infection status. This work reports on the observation of two independent instances of spontaneous change in the endophyte fungus that manifests as changes in the host grass vegetative morphology; one involving a genetically modified Epichloë festucae inoculated into a perennial ryegrass (Lolium perenne) population and the other a resident wild type Neotyphodium lolii. The relationship between wild type and variant fungus is confirmed as is the connection between variant fungus and host morphology. This work demonstrates that spontaneous in-planta changes in fungal endophytes occur and that these can impact on fungus/host grass symbioses. Keywords: Neotyphodium, Epichloë, symbiosis, endophyte, perennial ryegrass

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