A field experiment with elevated atmospheric CO(2)-mediated changes to C(4) crop-herbivore interactions

The effects of elevated CO(2) (E-CO(2)) on maize and Asian corn borer (ACB), Ostrinia furnacalis, in open-top chambers were studied. The plants were infested with ACB and exposed to ambient and elevated (550 and 750 μl/l) CO(2). E-CO(2) increased the plant height and kernel number per ear. The plants had lower nitrogen contents and higher TNC: N ratios under E-CO(2) than at ambient CO(2). The response of plant height to E-CO(2) was significantly dampened in plants with ACB infestation. However, the weight gain of the survivors declined in plants grown under E-CO(2). Moreover, the plant damage caused by ACB was not different among the treatments. Overwintering larvae developed under E-CO(2) had a lower supercooling point than those developed under ambient CO(2). The results indicated that there was a positive effect of E-CO(2) on the accumulation of maize biomass, i.e., the “air-fertilizer” effect, which led to a nutritional deficiency in the plants. The fitness-related parameters of ACB were adversely affected by the CO(2)-mediated decreased in plant nutritional quality, and ACB might alter its food consumption to compensate for these changes. Larval damage to maize under E-CO(2) appears to be offset by this “air-fertilizer” effect, with reductions in larval fitness.