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Responses of Three Generations of Cotton Bollworms Feeding on Wheat Grown in Air of Ambient and Double-Ambient CO2 Concentration
Wu, G., Chen, F.-J. and Ge, F. 2006. Response of multiple generations of cotton bollworm Helicoverpa armigera Hubner, feeding on spring wheat, to elevated CO2. Journal of Applied Entomology 130: 2-9.

What was done
The authors grew spring wheat (Triticum aestivum L.) from seed to maturity in pots placed within open-top chambers maintained at either 370 or 750 ppm CO2 in Sanhe County, Hebei Province, China, after which they reared three generations of cotton bollworms (Helicoverpa armigera Hubner) on the milky grains of the wheat, while monitoring a number of different bollworm developmental characteristics.

What was learned
Wu et al. report that "significantly lower pupal weights were observed in the first, second and third generations," and that "the fecundity of H. armigera decreased by 10% in the first generation, 13% in the second generation and 21% in the third generation," resulting in a "potential population decrease in cotton bollworm by 9% in the second generation and 24% in the third generation." In addition, they say that "population consumption was significantly reduced by 14% in the second generation and 24% in the third generation," and that the efficiency of conversion of ingested food was reduced "by 18% in the first generation, 23% in the second generation and 30% in the third generation."

What it means
In consideration of their several important findings, the Chinese researchers concluded that "net damage of cotton bollworm on wheat will be less under elevated atmospheric CO2," while noting that "at the same time, gross wheat production is expected to increase by 63% under elevated CO2."

Reviewed 14 June 2006