Open Collections

Ha, Kyu

University of British Columbia

Atmospheric CO₂ has been rising rapidly. Elevated CO₂ may disrupt plant-insect interactions by inducing changes in plant chemistry. Elevated CO₂ can suppress jasmonic acid (JA)-regulated hormonal defense and enhance salicylic acid (SA)-regulated defense against insect herbivores. However, insect responses to CO₂-induced changes in plant chemistry are unpredictable and species-dependent. Many factors such as differences in adaptation to host defense or mode of feeding can contribute to the wide diversity of insect responses. However, many herbivore studies at elevated CO₂ only consider one herbivore species. To fill this knowledge gap, I tested multiple insect species to examine species-specific responses to plants grown under elevated CO₂. I evaluated the change in mass and leaf matter consumed for two caterpillars (Plutella xylostella and Spodoptera exigua), and the change in population growth of one aphid species (Myzus persicae), on Arabidopsis thaliana reared at elevated CO₂ as a model Brassicaceae plant. I investigated the performance of three lepidopteran pests (Manduca sexta, Spodoptera exigua and Trichoplusia ni) on tomatoes (Solanum lycopersicum) grown at elevated CO₂ levels as a model Solanaceae plant. To evaluate the role of CO₂-induced changes in hormonal defense, I tested insect herbivory on plant genotypic mutants under-expressing JA or SA (JA- and SA-) in A. thaliana, and JA over-expressing (JA+) or JA- mutants in S. lycopersicum. I also investigated CO₂-induced changes in plant biomass, and for tomato, levels of terpenes, which can have anti-herbivory effects. Plant genotype affected caterpillar performance in both plant species, where insects weighed more on JA- plants. Caterpillars did not respond to CO₂-treatment in A. thaliana trials, while there were species-specific differences in insect responses to CO₂-treatment in S. lycopersicum trials. In S. lycopersicum, M. sexta mass increased while S. exigua mass decreased and T. ni mass did not change on CO₂-enriched plants. Elevated CO₂ decreased the concentration of two monoterpenes in wild type tomato. M. persicae performance was unaffected by CO₂ or genotype. These results suggest that elevated CO₂ may not significantly alter the performance of P. xylostella, S. exigua and M. persicae on A. thaliana, while M. sexta feeding on tomato may increase at higher CO₂.

Text

2024-04-29

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88088

Integrated Studies in Land and Food Systems

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/