Elevated CO2 and temperature alter specific‐species population dynamic and interspecific competition of three wheat aphids

Abstract

AbstractAtmospheric warming, combined with projected atmospheric carbon dioxide (ab. CO2) level arising, may have marked ecological effects on growth of agricultural crop plants, and in turn affect the higher trophic level of insect herbivores. In this study, the effects of elevated CO2 (i.e., 650 μL/L vs. ambient 400 μL/L) and temperature (ab. T; ambient vs. ambient +0.6°C) on the population abundance and the interspecific competition among three co‐occurring species of wheat aphids (Sitobion avenae, Rhopalosiphum padi and Schizaphis graminum) were studied. The results indicated that wheat plants had higher biomass and yields when grown under elevated CO2 in contrast to ambient CO2, and elevated T had no significant effect on the biomass and yields of wheat plants. Elevated CO2 significantly decreased the population dynamic level of S. avenae, and increased the population dynamic levels of R. padi and S. graminum; Elevated T significantly decreased the population dynamic level of S. avenae and significantly increased the population dynamic level of R. padi. Moreover, elevated T significantly decreased the niche breadth of S. avenae and S. graminum, respectively, while elevated CO2 had no significant effect on the three species niche breadth. Furthermore, elevated CO2 and T both significantly increased the niche overlap index (ab. NOI) between S. avenae and R. padi, as well as between R. padi and S. graminus, elevated T significantly reduced the NOI between S. avenae and S. graminus. This study provides evidence that elevated CO2 and T can alter the species‐specific population abundance of three wheat aphids, and aggravate two major interspecific competition among these three co‐occurring species of wheat aphids by increasing their spatial overlap.