Elevated Carbon Dioxide and Nitrogen Impact Wheat and Its Aphid Pest.

The rise in atmospheric carbon dioxide (CO) generally increases wheat biomass and grain yield but decreases its nutritional value. This, in turn, can alter the metabolic rates, development, and performance of insect pests feeding on the crop. However, it is unclear how elevated CO (eCO) and nitrogen (N) input affect insect pest biology through changes in wheat growth and tissue N content. We investigated the effect of three different N application rates (low, medium, and high) and two CO levels (ambient and elevated) on wheat growth and quality and the development and performance of the bird cherry-oat aphid, a major cereal pest worldwide, under controlled environmental conditions. We found that eCO significantly decreased total aphid fecundity and wheat N content by 22 and 39%, respectively, when compared to ambient CO (aCO). Greater N application significantly increased total aphid fecundity and plant N content but did not offset the effects of eCO. Our findings provide important information on aphid threats under future CO conditions, as the heavy infestation of the bird cherry-oat aphid is detrimental to wheat grain yield and quality.