Abstract: The lifetables of 3rd and 4th generation of cotton bollworm Helicoverpa armigera Hubner were established by action factors under four different control conditions.The results showed that under natural control,the egg parasitic rates of 3rd and 4th cotton bollworm were 4.39% and 1.19%,the predatory rates were 21.11% and 15.80%,and the larvae parasitic rates were 19.34% and 16.20% respectively.The indexes of population trend were only 0.0032 and 0.0014 respectively,after using selective pesticides IKI and Bt to control cotton bollworm.Though the index of population trend decreased to 48.66% and 61.67% after contantly praying chemical pesticides,the number of predators also decreaseed to 23.48% and 41.26% respectively.Transgenic Bt cotton could inhibit the population increase of cotton bollworm,but had no effect on predators.The parasitic rates of 3rd and 4th cotton bollworm on Transgenic Bt cotton were 51.14% and 0% respectively,as compared to control.

Key words: Cotton bollworm, Control means, Lifetable, Interference index of population control(IIPC)