We quantified effects of two levels of nutrient availability (50 and 200 ppm N, with N:P:K applied in ratio of 3:1:2) on constitutive and rapid induced resistance (RIR) of black poplar (Populus nigra) to gypsy moth (Lymantria dispar) and whitemarked tussock moth (Orgyia leucostigma). The high nutrient treatment dramatically increased relative growth rate, total biomass, and total leaf area, while constitutive foliar phenolic concentrations were decreased. Constitutive resistance of poplar to gypsy moth was decreased in the high relative to the low fertility treatment, but nutrient availability had no effect on constitutive resistance to whitemarked tussock moth. In response to localized herbivory, expression of RIR to gypsy moth was most pronounced in the high fertility treatment. In contrast, RIR to whitemarked tussock was expressed only in the low fertility treatment. These results suggest that the effects of nutrient availability on the expression of RIR may represent a largely over-looked source of variation in plant / herbivore interactions.
Species 1: Lepidoptera Lymantriidae Lymantria species (gypsy moth)
Species 2: Lepidoptera Lymantriidae Orgyia leucostigma (whitemarked tussock moth)
Keywords: carbon allocation, fertilization
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