Influence of elevated CO2 on development and food utilization of target armyworm Mythimna separata fed on transgenic Bt maize infected by nitrogen-fixing bacteria

Abstract

Bt crops will face a new ecological risk of reduced effectiveness against target-insect pests owing to the general decrease in exogenous-toxin content in Bt crops grown under elevated CO2. How to deal with this issue may affect the sustainability of transgenic crops as an effective pest management tool especially under future CO2 raising. In this study, azotobacters, as being one potential biological regulator to enhance crops nitrogen utilization efficiency, were selected and the effects of Bt maize and non-Bt maize infected by Azospirillum brasilense and Azotobacter chroococcum on development and food utilization of target Mythimna separate were studied under ambient and elevated CO2. The results indicated that azotobacter infection significantly increased larval life-span, pupal duration, RCR and AD of M. separata, and significantly decreased RGR, ECD and ECI of M. separata fed on Bt maize; There were opposite trends in development and food utilization of M. separata fed on non-Bt maize infected with azotobacters compared with the buffer control regardless of CO2 level. Presumably, the application of azotobacter infection could make Bt maize facing lower field hazards from the target pest of M. separate, and finally improve the resistance of Bt maize against target lepidoptera pests especially under elevated CO2.\n\nSummary statementElevated CO2 effect on development and food utilization of target armyworm Mythimna separata fed on Bt maize infected by azotobacter, Azospirillum brasilense and Azotobacter chroococcum