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Issue No. 10, Article 2/June 2, 2006

Elevated Carbon Dioxide and Ozone in the Atmosphere Influence Egg Laying by Variant Western Corn Rootworms

In a recent journal article (Environmental Entomology, June 2006), researchers described how elevated atmospheric carbon dioxide (CO2) and ozone (O3) may affect egg laying by variant western corn rootworm adults in soybean fields. The authors indicated that global atmospheric CO2 has increased 20% in the last century and may increase another 48% by 2050. Concentrations of O3 also may increase another 20% midway through this new century as well. During 2003 and 2004, the investigators conducted their experiments on the SoyFACE (free air gas concentration enrichment) site located south of Champaign-Urbana. For more information about this unique experimental site, please refer to the SoyFACE web site. Stephen P. Long, professor in the Department of Crop Sciences at the University of Illinois, is the overall project leader for this novel study area.


SoyFACE experimental site, Department of Crop Sciences at the University of Illinois.

The researchers offered the following remarks in their article abstract: "Although elevated CO2 and O3 did not have an effect on adult female densities of the variant western corn rootworm, they did significantly affect egg densities. Approximately twice as many eggs were found in the soil of soybean plots exposed to elevated CO2 compared with ambient control plots or those with elevated O3. Egg densities were even greater (approximately three times) in plots with the elevated CO2 and O3 combination treatment than in ambient plots. This suggests that rising CO2 and O3 are stimulating egg-laying by the variant western corn rootworm, potentially increasing population densities and risk of damage to the subsequent corn crop."

These findings suggest that western corn rootworms in the future may exert even greater pressure on corn production. Transgenic corn rootworm hybrids, along with soil insecticides, will certainly help us manage corn rootworm damage well into the future; however, this insect is an adaptable foe. We anticipate continued research in the area of changing atmospheric conditions to help elucidate why egg laying by variant western corn rootworms increased so significantly. We thank Jared B. Schroeder for providing leadership on this study, which served as part of his master's thesis research in the Department of Crop Sciences at the University of Illinois.--Mike Gray

Reference

Schroeder, J.B., M.E. Gray, S.T. Ratcliffe, R.E. Estes, and S.P. Long. 2006. Effects of elevated CO2 and O3 on a variant of the western corn rootworm (Coleoptera: Chrysomelidae). Environmental Entomology, 35(3): 637-644.

Author:
Mike Gray

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