The accidental introduction of the Chestnut blight fungus, Cryphonectria parasitica, virtually eliminated American chestnut from eastern forests. Efforts at developing varieties resistant to blight have been somewhat successful, but resistance to one stressing agent may affect susceptibility to a second stressor, suggesting that blight-resistant chestnut could alter susceptibility to herbivory. I investigated herbivore suitability and foliar chemistry of five chestnuts, representing a spectrum of blight resistance. Gypsy moth, Lymantria dispar, larvae, and Japanese beetle, Popillia japonica, adults were assayed on excised chestnut foliage, and consumption was measured. Concurrently, leaves were analyzed for carbohydrates, tannins, and nitrogen.
Suitability of foliage varied between and within chestnut species for both generalist herbivores, but this did not always coincide with chestnut blight resistance, nor was it consistent between herbivores. Similarly, foliar chemistry varied among species.
Blight resistance and herbivore resistance appear to operate independently in the chestnut system. Herbivore susceptibility may be guild-specific, since herbivores with different modes of feeding vary in their ability to exploit these hosts.
Enhanced herbivore consumption of blight-resistant chestnut has implications with respect to the restoration of chestnut to eastern deciduous forests, since intense herbivore pressure could compromise seedling growth and survival, and play a role in sustaining potentially damaging herbivore populations.
Species 1: Lepidoptera Lymantriidae Lymantria dispar (gypsy moth)
Species 2: Coleoptera Scarabaeidae Popillia japonica (Japanese beetle)
Species 3: Fagales Fagaceae Castanea dentata (American chestnut)
Keywords: chestnut blight, herbivory
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