Using population energetics to evaluate potential damage to cotton by the cotton bollworm Helicoverpa armigera (Lepidoptera

Energy dynamics of a natural population of the cotton bollworm, Helicoverpa armigera, was investigated using a combination of field surveys and a laboratory energy budget experiment. The ingestion and production of the population (during generations 2nd-4th) were 29.59 kJ/m2 and 2.69 kJ/m2, respectively. The assimilation efficiency ranged from 64.67 to 75.72%, and the net ecological efficiency was 9.21-16.21%. Of the fruit production of cotton plants, 0.17% was consumed and 9.80% damaged by the bollworm population over the entire study period. Both percentages were significantly higher in the 2nd generation than those in the 3rd and 4th generations. This work provides strong evidence that H. armigera is a major pest in a cotton agroecosystem in North China, and the second generation was the key damage-causing generation.