Effects of Host Plants Reared under Elevated CO2 Concentrations on the Foraging Behavior of Different Stages of Corn Leaf Aphids Rhopalosiphum maidis

Climate change is a major environmental concern and is directly related to the increasing concentrations of greenhouse gases. The increase in concentrations of atmospheric carbon dioxide (CO2), not only affects plant growth and development, but also affects the emission of plant organic volatile compounds (VOCs). Changes in the plant odor profile may affect the plant-insect interactions, especially the behavior of herbivorous insects. In this study, we compared the foraging behavior of corn leaf aphid (Rhopalosiphum maidis) on barley (Hordeum vulgare L.) seedlings grown under contrasted CO2 concentrations. During the dual choice bioassays, the winged and wingless aphids were more attracted by the VOCs of barley seedlings cultivated under ambient CO2 concentrations (aCO(2); 450 ppm) than barley seedlings cultivated under elevated CO2 concentrations (eCO(2); 800 ppm), nymphs were not attracted by the VOCs of eCO(2) barley seedlings. Then, volatile compositions from 14-d-old aCO(2) and eCO(2) barley seedlings were investigated by GC-MS. While 16 VOCs were identified from aCO(2) barley seedlings, only 9 VOCs were found from eCO(2) barley seedlings. At last, we discussed the potential role of these chemicals observed during choice bioassays. Our findings lay foundation for functional response of corn leaf aphid under climate change through host plant modifications.