Environmental Entomology (2003) 32, 452-462

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David R. Coyle, Joel D. McMillin, Richard B. Hall and Elwood R. Hart (2003)
Effects of cottonwood leaf beetle (Coleoptera: Chrysomelidae) larval defoliation, clone, and season on Populus foliar phagostimulants
Environmental Entomology 32 (3), 452-462
Abstract: The cottonwood leaf beetle, Chrysomela scripta F., is a serious defoliator of plantation Populus in the United States. Current control methods include biorational and synthetic chemicals as well as selecting Populus clones resistant or tolerant to C. scripta defoliation. Specific ratios of long-chain fatty alcohols to alpha-tocopherylquinone (alpha-TQ) on the leaf surface of Populus spp. act as phagostimulants to adult C. scripta. The chemical concentrations and ratios vary among Populus clones; however, the effect of defoliation on the subsequent production of these chemicals is unknown. We investigated the effects of defoliation, clone, and season on Populus leaf surface chemical production. Chemical concentrations and ratios were monitored in 1998 and 1999 on eight Populus clones with and without larval C. scripta defoliation. Chemicals were extracted from the leaf surface and analyzed via gas chromatography. Larval C. scripta defoliation rarely caused changes in leaf surface chemistry at the defoliation levels tested; however, the production of these phagostimulants did vary by clone and season. Foliar alcohol and alpha-TQ concentrations and alpha-TQ:total alcohol ratios differed significantly among clones. Furthermore, alpha-TQ concentrations and alpha-TQ:total alcohol ratios varied temporally in some, but not all, clones. In general, foliar alcohol and alpha-TQ concentrations either did not vary or increased, but alpha-TQ:total alcohol ratios declined throughout the growing season. This research illustrates that the production of leaf surface phagostimulants is not a function of defoliation, but is most likely controlled by genetic and physiologic processes. Additionally, because Populus clones vary in their foliar chemistry, this variation could be exploited in tree breeding programs.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): David R. Coyle, Elwood R. Hart

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host
general biology - morphology - evolution

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Chrysomela scripta Poplar/aspen (Populus)