title: Effects of elevated carbon dioxide and ozone on the phytochemistry of aspen and performance of an herbivore.
abstract: The purpose of this study was to assess the independent and interactive effects of CO(2), O(3), and plant genotype on the foliar quality of a deciduous tree and the performance of a herbivorous insect. Two trembling aspen (Populus tremuloides Michaux) genotypes differing in response to CO(2) and O(3) were grown at the Aspen FACE (Free Air CO(2) Enrichment) site located in northern Wisconsin, USA. Trees were exposed to one of four atmospheric treatments: ambient air (control), elevated carbon dioxide (+CO(2); 560 microl/l), elevated ozone (+O(3); ambient x1.5), and elevated CO(2)+O(3). We measured the effects of CO(2) and O(3) on aspen phytochemistry and on performance of forest tent caterpillar (Malacosoma disstria Hübner) larvae. CO(2) and O(3) treatments influenced foliar quality for both genotypes, with the most notable effects being that elevated CO(2) reduced nitrogen and increased tremulacin levels, whereas elevated O(3) increased early season nitrogen and reduced tremulacin levels, relative to controls. With respect to insects, the +CO(2) treatment had little or no effect on larval performance. Larval performance improved in the +O(3) treatment, but this response was negated by the addition of elevated CO(2) (i.e., +CO(2)+O(3) treatment). We conclude that tent caterpillars will have the greatest impact on aspen under current CO(2) and high O(3) levels, due to increases in insect performance and decreases in tree growth, whereas tent caterpillars will have the least impact on aspen under high CO(2) and low O(3) levels, due to moderate changes in insect performance and increases in tree growth.
authors.affiliation: Department of Entomology, University of Wisconsin, 237 Russell Labs, 1630 Linden Drive, Madison, WI 53706, USA. kopper@entomology.wisc.edu
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Kopper
authors.forename: Richard L
authors.initials: RL
authors.lastname: Lindroth
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior; D005838:Genotype; D005960:Glucosides / Q000032:analysis; D007814:Larva / Q000187:drug effects / Q000502:physiology; D007915:Lepidoptera / Q000187:drug effects* / Q000502:physiology; D009584:Nitrogen / Q000032:analysis; D010126:Ozone / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism / Q000469:parasitology; D032107:Populus / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000469:parasitology*; D013997:Time Factors; D014922:Wisconsin
chemical_list: D005960:Glucosides; D002245:Carbon Dioxide; C095421:tremulacin; D010126:Ozone; D009584:Nitrogen