title: The inhibition of phenolic biosynthesis in damaged and undamaged birch foliage and its effect on insect herbivores.
abstract: 1. The leaves of Betula pendula Roth trees were damaged artificially, or by insect-grazing. Both induced an increase in phenolic levels in damaged leaves, larger in the case of insect attack.-2. Some of the damaged trees were sprayed with an inhibitor of phenolic biosynthesis, (aminoxy) acetic acid, which led to a reduction in phenolic levels in both undamaged and damaged leaves. Hence both the effects of damage per se and damage-induced changes in foliage phenolic levels on insect feeding preference could be examined using this technique.-3. Herbivore feeding preferences were assessed in the laboratory by comparing damaged and undamaged leaves, with or without phenolic inhibition, using caterpillars of a natural birch feeder, Apocheima pilosaria D. & S. (Lepidoptera: Geometridae) and a non-birch feeder, Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae). Neither species showed any significant preferences and appeared indifferent to damage, irrespective of whether the trees had their damage-induced phenolic synthesis blocked.-4. The implications of these results for "induced defense" theory are discussed.
authors.affiliation: Department of Biology, University of York, Heslington, YO1 5DD, York, UK.
authors.forename: S E
authors.initials: SE
authors.lastname: Hartley
keywords: Belula; Feeding-preference; Leaf-damage; Phenolics; Spodoptera