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The Direct Effects of Elevated CO2 on the Asian Corn Borer

Paper Reviewed
Xie, H., Zhao, L., Yang, Q., Wang, Z. and He, K. 2015. Direct effects of elevated CO2 levels on the fitness performance of Asian corn borer (Lepidoptera: Crambidae) for multigenerations. Climate Dynamics 44: 3469-3479.

In addition to impacting plants, future levels of atmospheric CO2 may also affect the biology of animals. However, there presently exists only a limited body of research in this area.

Writing as background for their work, Xie et al. (2015) say that "few studies have examined the direct effects of elevated CO2 on insects," yet they note that "understanding the direct response of insects to elevated CO2 should help to elucidate the mechanistic bases of the effects of elevated CO2 on the interactions of insects with plants." And, therefore, the team of five Chinese researchers decided to investigate the direct impact of elevated CO2 on the Asian corn borer (Ostrinia furnacalis), a moth that consistently causes 10-30 percent maize yield losses annually in China.

To accomplish their objective, Xie et al. reared O. furnacalis on an artificial diet in closed environment chambers maintained at either ambient (350-400 ppm) or elevated (550 and 750 ppm) CO2, where they measured survival, growth and developmental parameters over a period of six generations. The artificial diet was purposely selected so as to avoid indirect effects of the nutrition deficiency that sometimes develops in plant leaves under elevated CO2.

In describing their findings, Xie et al. report that both larval and overall survival rate of the Asian corn borer were reduced (by ten and thirteen percent, respectively) under high CO2 conditions (750 ppm). Additionally, they found that mean larval development times were significantly longer across the generations (by seven and sixteen percent, respectively, for the 550 and 750 ppm treatments compared to ambient). Pupal weight was also reduced under elevated CO2. And these observations, in the words of the authors, "suggest that O. furnacalis larvae and pupae reared in elevated CO2 conditions would have lower fitness, including increased mortality, reduced pupal weight and, in multiple generations, longer development times," all of which is good news as it reduces the future annual loss of maize to this significant insect pest.

Posted 2 December 2016