ARS | Publication request: DETRIMENTAL AND NEUTRAL EFFECTS OF WILD BARLEY-NEOTYPHODIUM ENDOPHYTE ASSOCIATIONS ON INSECT SURVIVAL

Submitted to: International Neotyphodium Grass Interactions
Publication Type: Other
Publication Acceptance Date: March 15, 2004
Publication Date: May 23, 2004
Citation: Clement, S.L., Elberson, L.R., Rosque-Perez, N.A., Schotzke, D. 2004. Detrimental and neutral effects of wild barley-neotyphodium endophyte associations on insect survival. In: Kallenbach, R., Rosenkuans, C. Jr, Lock, T.R., editors. Proceedings 5th International symposium on Neotyphodium/Grass Interactions. Paper No. 307.

Technical Abstract: The literature is replete with examples of chemical variation in plants and the role this variation plays in determining the outcome of plant-insect interactions. For example, chemical heterogeneity typifies fungal endophyte (Epicholë and asexual Neotyphodium forms) - temperate grass associations, with insect resistance (deterrence, toxicity) the result of the fungus or the grass-fungus interaction producing specific alkaloids. In the absence of specific alkaloid types and concentrations, grass-endophyte interactions can have neutral effects on insects. Factors that can influence variation in alkaloid production, and hence the expression of insect resistance, are the host plant genotype/species, endophyte genotype, and external factors such as temperature and soil fertility. This poster expands our understanding of the extent to which endophyte infection protects wild grasses from insect attack. Specifically, we present the results from greenhouse and growth chamber experiments involving endophyte-infected wild barley species (perennial Hordeum spp.) and insect associates (Russian wheat aphid, Hessian fly). These insects and wild barleys overlap in their native ranges (Asiatic Turkey to Central Asia). In two of four wild barley-Neotyphodium associations, Russian wheat aphid survival was significantly reduced on infected clones, compared to uninfected replicates. By contrast, Hessian fly survival was reduced on infected clones of all wild barley accessions. When we quantified the survival of Mediterranean and European aphids on plants of the same four associations, we found equivalent survival rates of bird cherry-oat aphid on infected and uninfected clones, and reduced survival of rose grass aphid on infected clones of only one wild barley-endophyte association. These collective results support published research showing that phytophagous insects are affected differently by exposure to endophyte-infected grasses. They also show that endophyte infection can profoundly alter the suitability of a wild grass to Russian wheat aphid and Hessian fly, two major cereal pests.