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Zoysiagrass (Zoysia spp.) resistance to fall armyworm (Spodoptera frugiperda): polyphenols and flavonoids--components of resistance

Hale, Trent C., Reinert, James A., White, Richard H., Snook, M.E.
Acta horticulturae 2008 no.783 pp. 507
Spodoptera frugiperda, insect pests, plant pests, Zoysia japonica, Zoysia matrella, turf grasses, pest resistance, polyphenols, flavanoids, high performance liquid chromatography, phytochemicals, temporal variation, nitrogen fertilizers, cultivars, mortality, chemical concentration, phytotoxins, resistance mechanisms, Texas
Leaf tissue collected from six zoysiagrass (Zoysia spp.) cultivars was analyzed for polyphenols and flavonoids by high performance liquid chromatography (HPLC). The experiment investigated the effects of sampling date and N fertilization rate on green leaf chemistry of zoysiagrass and their relationship to fall armyworm (FAW) [Spodoptera frugiperda (J. E. Smith)] resistance. Six zoysiagrasses cultivars {'Crowne' (Z. japonica Steud.), 'Palisades' (Z. japonica Steud.), 'El Toro' (Z. japonica Steud.), 'Meyer' (Z. japonica Steud.), 'Cavalier' [Z. matrella (L.) Merr.], and 'Emerald' (Z. japonica Stued. x Z. tenuifolia Willd. ex Trin.)} were planted in a randomized split-plot design with 4 replicates using cultivars as the main plot and 12.2 and 48.9 kg of N ha-1 month-1 [(NH4)2SO4] as the split plots. Flavonoid concentration decreased as the amount of applied N increased. Flavonoid concentration was greatest in June and steadily declined throughout July and August. Two unidentified flavonoids (luteolin-glycosides) were consistently associated with FAW mortality when analyzed by stepwise regression techniques. Unidentified luteolin 3 had an inverse relationship with mortality, while unidentified luteolin 9 was positively correlated with mortality. Additional research is needed to determine if the concentration of luteolins found in resistant zoysiagrasses are sufficient to cause biocidal activity in FAW.