title: Responses of leaf beetle larvae to elevated [CO₂] and temperature depend on Eucalyptus species.
abstract: It is essential to understand the combined effects of elevated [CO2] and temperature on insect herbivores when attempting to forecast climate change responses of diverse ecosystems. Plant species differ in foliar chemistry, and this may result in idiosyncratic plant-mediated responses of insect herbivores at elevated [CO2] and temperature. We measured the response of the eucalypt leaf beetle Paropsis atomaria (Coleoptera: Chrysomelidae) feeding on Eucalyptus tereticornis and Eucalyptus robusta. Seedlings were grown at ambient (400 µmol mol(-1)) or elevated (640 µmol mol(-1)) [CO2] and ambient (26/18 °C day/night) or elevated (ambient + 4 °C) temperature in a greenhouse for 7 months. Larvae fed on flush leaves from egg hatch to pupation while being directly exposed to these conditions. Elevated [CO2] reduced foliar [N] and [P], while it increased total nonstructural carbohydrates and the C:N ratio. Elevated temperature increased foliar [N] in E. robusta but not E. tereticornis. Plant-mediated effects of elevated [CO2] reduced female pupal weight and increased developmental time and leaf consumption. Larval survival at elevated [CO2] was impacted differently by the two host plant species; survival increased on E. robusta while it decreased on E. tereticornis. Elevated temperature accelerated larval development but did not impact other insect parameters. We did not detect a CO2 × temperature interaction, suggesting that elevated temperature as a combined direct and plant-mediated effect may not be able to ameliorate the negative plant-mediated effects of elevated [CO2] on insect herbivores. Our study highlighted host-plant-specific responses of insect herbivores to climate change factors that resulted in host-plant-specific survival.
authors.affiliation: Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW, 2751, Australia, a.gherlenda@uws.edu.au.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Gherlenda
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Haigh
authors.forename: Ben D
authors.initials: BD
authors.lastname: Moore
authors.forename: Scott N
authors.initials: SN
authors.lastname: Johnson
authors.forename: Markus
authors.initials: M
authors.lastname: Riegler
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D057231:Climate Change; D001517:Coleoptera / Q000378:metabolism / Q000502:physiology*; D005052:Eucalyptus / Q000254:growth & development / Q000502:physiology*; D005260:Female; D060434:Herbivory; D007814:Larva / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology; D011679:Pupa / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D013696:Temperature
chemical_list: D002245:Carbon Dioxide