Leaf Age and Related Factors Affecting Endophyte-mediated Resistance to Fall Armyworm (Lepidoptera: Noctuidae) in Tall Fescue

Hardy, Tad N.; Clay, Keith; Hammond, A. M.

doi:10.1093/ee/15.5.1083

Cited by 67 publications

(36 citation statements)

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“…Adverse effects on fall armyworm growth in our study became more apparent with each trial as plants aged. Fall armyworm neonates signiÞ-cantly preferred and fed more on older, uninfected tall fescue leaves, compared with similar-aged, infected counterparts (Hardy et al 1986). Similarly, survival and larval weights were more adversely affected with increasing leaf age.…”

Section: Discussionmentioning

confidence: 99%

Grass Species and Endophyte Effects on Survival and Development of Fall Armyworm (Lepidoptera: Noctuidae)

Braman

Duncan

Engelke

et al. 2002

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Grass selections including 10 zoysiagrasses, 18 paspalums, 34 Bermuda grasses, tall fescue, creeping red fescue, and perennial ryegrasses with and without endophyte were evaluated for potential resistance to fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae. Laboratory evaluations assessed the degree of antibiosis among >70 grass lines to first-instar fall armvworms. When all parameters measured were considered, the trend in resistance to fall armyworm among endophyte-infected (E+) and endophyte-free (E-) cool season grasses from greatest to least was: 'Dawson' E+ > APR 1234 > 'Dawson' E- > 'Rosalin' E+ > Lp 5425, 'Rosalin' E-, ATF 480 > 'Tulsa' or: E+ slender creeping red fescue > E+ turf- type perennial ryegrass > E- slender creeping red fescue > E+ forage-type perennial ryegrass > E- forage-type perennial ryegrasses, and E+ tall fescue > E- turf-type tall fescue. Among warm season grasses larval weight gain was reduced on all zoysiagrasses. Larval weight gain also was lower on the Bermuda grasses 'Tifsport', 'Tifgreen', 97-4, 97-14, 97-22, 97-28, 97-39, 97-40,97-54, 98-15, 98-30, and 98-45 than when larvae were fed 'Tulsa' tall fescue or the diet control. Only APR1234 and 'Dawson' creeping red fescue reduced larval survival to the same extent that was observed for zoysiagrasses. Survival on Bermuda grasses was least on 97-8. Seashore paspalums were only rarely less susceptible to fall armyworm than tall fescue, although pupal weights were consistently lower on 'Temple 1' and 'Sea Isle 1' paspalums than that on 'Tulsa' tall fescue. Genetic resistance to key grass pests can reduce insecticide use and simplify management of these cultivars.

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Section: Discussionmentioning

confidence: 99%

Grass Species and Endophyte Effects on Survival and Development of Fall Armyworm (Lepidoptera: Noctuidae)

Braman

Duncan

Engelke

et al. 2002

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“…We placed each insect into an individual transparent plastic box (16 by 11 by 4 cm) between two food items: a 10-cm leaf segment of a randomly selected endophyte-symbiotic F. subverticillata and the same sized leaf segment from a randomly selected, disinfected F. subverticillata plant. Cut leaves have been commonly used for assaying food preference and performance in prior experiments, including in grassÐ endophyte studies (Hardy et al 1986, Clay 1988, Bultman and Bell 2003, Ball et al 2006, Bultman et al 2006. Clearly, plant quality may be altered in detached leaves compared with whole plants; however, these assays can still inform our understanding of insect preference, especially when preferences are strong.…”

Section: Choice Experimentsmentioning

confidence: 99%

Endophyte-Mediated Resistance to Herbivores Depends on Herbivore Identity in the Wild GrassFestuca subverticillata

Afkhami

Rudgers

2009

Environ Entomol

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Understanding factors that affect the context dependency of species interactions has been identified as a critical research area in ecology. The presence of symbionts in host plants can be an important factor influencing the outcome of plant-insect interactions. Similarly, herbivore identity can alter the outcome of plant-symbiont interactions. Symbiotic foliar fungal endophytes confer resistance to herbivores in economically important agronomic grasses, in part through the production of alkaloids. Although endophytes are common in nature, relatively little is known about their effects on herbivores of native, wild grass species, and a recent meta-analysis suggested that endophytes are only beneficial in agronomic settings. In this study, we performed choice trials for five insect species and a greenhouse experiment with one species to assess effects of the fungal endophyte Neotyphodium sp. on herbivores of the wild grass Festuca subverticillata. In feeding trials, endophyte presence altered the preference of all five insect species tested. However, the magnitude and direction of preference varied among species, with Pterophylla camellifolia (F.), Spodoptera frugiperda (J. E. Smith), and Rhopalosiphum padi L. preferring endophyte-disinfected plants and Encoptolophus costalis (Scudder) and Romalea guttata (Houttuyn) preferring endophyte-symbiotic plants. Despite reducing insect preference, the endophyte had no significant effect on S. frugiperda performance in a no-choice greenhouse experiment and did not increase plant growth in response to this herbivore. Our results show that endophyte-mediated resistance to herbivory depends strongly on herbivore identity and suggest that the fitness consequences of endophyte symbiosis for host plants will be context dependent on the local composition of insect herbivores.

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“…The ease of rearing, knowledge of its development and its wide graminoid host range make it an ideal model insect for herbivore assays. Earlier experiments have found reduced larval weights and delayed development of S. frugiperda larvae reared on endophyte-infected versus uninfected perennial ryegrass, tall fescue, and other grasses or sedges (Hardy et al 1985(Hardy et al , 1986Cheplick and Clay 1988). In this study we investigated to what extent the development and reproductive success of S. frugiperda were affected when reared on different genotypes of naturally infected, artificially infected and uninfected leaf material of B. sylvaticum.…”

Section: Introductionmentioning

confidence: 97%

Epichloë grass endophytes increase herbivore resistance in the woodland grass Brachypodium sylvaticum

Brem

Leuchtmann

2001

Oecologia

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Endophytic fungi of the genus Epichloë and their asexual Neotyphodium forms are thought to interact mutualistically with their host grasses, providing protection for the host against herbivores and pathogens mediated by fungal alkaloids. Most previous research has concentrated on agronomically important grasses, such as tall fescue, and its interactions with livestock grazers or invertebrate herbivores. In this study we focus on the woodland grass Brachypodium sylvaticum which is infected by the strictly host-specific endophyte Epichloë sylvatica. This fungus has two alternative modes of reproduction: the predominant asexual strains are seed-transmitted, whereas the rare sexual strains are capable of contagious spread by ascospores produced on stromata. To assess potential host protection from herbivory, we tested to what extent development of Spodoptera frugiperda, a noctuid generalist herbivore, was affected when fed on different genotypes of naturally infected (E), artificially infected (F), or uninfected (E) leaf material of B. sylvaticum. In a feeding assay, insect larvae performed significantly better on a diet of uninfected leaves, even though previous studies have not detected alkaloid production by E. sylvatica. A possible explanation for this result may be the presence of an unknown compound in infected plants, acting as metabolic toxin against S. frugiperda larvae. The negative effect on insect larvae was increased when they were fed on a diet artificially infected by a particular genotype (F), suggesting that content of allelochemicals may depend on the fungal genotype. In a dual-choice test, neonate S. frugiperda larvae initially preferred uninfected seedlings over naturally infected seedlings, but only during the first 6 h of the experiment. This suggests that the unknown compounds can act as weak insect-feeding deterrents. To assess herbivory in natural stands of the host grass, nine infected populations of B. sylvaticum were examined for feeding damage. Damage due to microherbivores and macroherbivores was equal in most populations. However, microherbivores (mostly insects) showed a clear preference for tillers bearing fungal stromata, whereas asymptomatically infected tillers were less damaged. Thus, herbivore resistance of infected plants appears to be correlated with the mode of reproduction of fungal genotypes. This result is of evolutionary significance, since asexual, seed-transmitted endophytes depend on host fitness and seed production for their dispersal.

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Leaf Age and Related Factors Affecting Endophyte-mediated Resistance to Fall Armyworm (Lepidoptera: Noctuidae) in Tall Fescue

Cited by 67 publications

References 0 publications

Grass Species and Endophyte Effects on Survival and Development of Fall Armyworm (Lepidoptera: Noctuidae)

Grass Species and Endophyte Effects on Survival and Development of Fall Armyworm (Lepidoptera: Noctuidae)

Endophyte-Mediated Resistance to Herbivores Depends on Herbivore Identity in the Wild GrassFestuca subverticillata

Epichloë grass endophytes increase herbivore resistance in the woodland grass Brachypodium sylvaticum

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