title: Responses of plant phenology, growth, defense, and reproduction to interactive effects of warming and insect herbivory.
abstract: Climate warming can modify plant reproductive fitness through direct and indirect pathways. Direct effects include temperature-driven impacts on growth, reproduction, and secondary metabolites. Indirect effects may manifest through altered species interactions, including herbivory, although studies comparing the interactive effects of warming and herbivory are few. We used experimental warming combined with herbivore exclusion cages to assess the interactive effects of climate warming and herbivory by Popillia japonica, the Japanese beetle, on flowering phenology, growth, defense, and lifetime reproduction of a biennial herb, Oenothera biennis. Regardless of temperature, herbivory delayed flowering phenology and, surprisingly, led to decreased levels of foliar defenses. At ambient temperatures, plants were able to compensate for herbivory by producing smaller seeds and increasing total seed production, leading to similar investment in seed biomass for plants exposed to and protected from herbivores. At elevated temperatures, plants had elevated total seed production, but herbivory had negligible impacts on flower and fruit production, and total lifetime seed biomass was highest in plants exposed to herbivores in warmed conditions. We speculate that warming induced a stress response in O. biennis resulting from low soil moisture, which in turn led to an increase in seed number at the expense of maternal investment in each seed. Plant-insect interactions might therefore shift appreciably under future climates, and ecologists must consider both temperature and herbivory when attempting to assess the ramifications of climate warming on plant populations.
authors.affiliation: Department of Biological Sciences, Florida International University, 3000 NE 151st Street, North Miami, Florida, 33181, USA.
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Lemoine
authors.affiliation: Department of Earth & Environmental Science, Boston University, 685 Commonwealth Avenue, Boston, Massachusetts, 02215, USA.
authors.forename: Dejeanne
authors.initials: D
authors.lastname: Doublet
authors.affiliation: Natural Chemistry Research Group, Department of Chemistry, University of Turku, Turku, FI-20500, Finland.
authors.forename: Juha-Pekka
authors.initials: JP
authors.lastname: Salminen
authors.affiliation: Department of Biological Sciences, Florida International University, 3000 NE 151st Street, North Miami, Florida, 33181, USA.|Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, California, 93106, USA.
authors.forename: Deron E
authors.initials: DE
authors.lastname: Burkepile
authors.affiliation: Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, Maryland, 21037, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Parker
mesh_terms: D000818:Animals; D002980:Climate; D060434:Herbivory; D007313:Insecta; D031665:Oenothera biennis; D010944:Plants; D012098:Reproduction
keywords: 
  Oenothera biennis
  ; 
  Popillia japonica
  ; climate change; compensation; fitness; herbivory; reproduction; secondary chemistry