Olfactory Preferences of Popillia japonica, Vanessa cardui, and Aphis glycines for Glycine max Grown Under Elevated CO2

• Published in: Environmental entomology 2010-08, Vol.39 (4), p.1291-1301
• Main Authors: O'Neill, Bridget F, Zangerl, Arthur R, Delucia, Evan H, Berenbaum, May R
• Format: Article
• Language: English
• Subjects: 2-hexenal; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Aphididae; Aphids; Aphis; Aphis glycines; Autoecology; Biological and medical sciences; Butterflies; carbon dioxide; Carbon Dioxide - metabolism; CHEMICAL ECOLOGY; climate change; Climatology. Bioclimatology. Climate change; Coleoptera; Earth, ocean, space; elevated atmospheric gases; Exact sciences and technology; External geophysics; Female; Fundamental and applied biological sciences. Psychology; Glycine max; Glycine max - chemistry; Glycine max - metabolism; Glycine max - parasitology; green leaf volatiles; herbivorous insects; host plants; Host-Parasite Interactions; insect pests; Insecta - physiology; kairomones; leaves; Male; Meteorology; odor compounds; odors; Oviposition; phytophagous insects; plant damage; Plant Leaves - chemistry; plant pests; Popillia japonica; Protozoa. Invertebrata; Smell; soybeans; Vanessa cardui; volatile compounds; Volatile Organic Compounds - analysis; Y-tube olfactometers
• ISSN: 0046-225X; 1938-2936; 0046-225X
• DOI: 10.1603/EN09036

Levels of atmospheric CO2 have been increasing steadily over the last century and are projected to increase even more dramatically in the future. Soybeans (Glycine max L.) grown under elevated levels of CO2 have larger herbivore populations than soybeans grown under ambient levels of CO2. Increased abundance could reflect the fact that these herbivores are drawn in by increased amounts of volatiles or changes in the composition of volatiles released by plants grown under elevated CO2 conditions. To determine impacts of elevated CO2 on olfactory preferences, Japanese beetles (Popillia japonica Newman) and soybean aphids (Aphis glycines Matsumura) were placed in Y-tube olfactometers with a choice between ambient levels of CO2 gas versus elevated levels of CO2 gas or damaged and undamaged leaves and plants grown under ambient levels of CO2 versus damaged and undamaged plants grown under elevated levels of CO2. All plants had been grown from seeds under ambient or elevated levels of CO2. Painted lady butterflies (Vanessa cardui L.) were placed in an oviposition chamber with a choice between plants grown under ambient and elevated levels of CO2. A. glycines and V. cardui showed no significant preference for plants in either treatment. P. japonica showed no significant preference between ambient levels and elevated levels of CO2 gas. There was a significant P. japonica preference for damaged plants grown under ambient CO2 versus undamaged plants but no preference for damaged plants grown under elevated CO2 versus undamaged plants. P. japonica also preferred damaged plants grown under elevated levels of CO2 versus damaged plants grown under ambient levels of CO2. This lack of preference for damaged plants grown under elevated CO2 versus undamaged plants could be the result of the identical elevated levels of a green leaf volatile (2-hexenal) present in all foliage grown under elevated CO2 regardless of damage status. Green leaf volatiles are typically released from damaged leaves and are used as kairomones by many herbivorous insects for host plant location. An increase in production of volatiles in soybeans grown under elevated CO2 conditions may lead to larger herbivore outbreaks in the future.