Abstract:By using indoor cotton leaf rearing, the effects of transgenic cotton on the growth and development of near-isogenic Helicoverpa armigera (Hübner) resistant to Cry1Ac was compared with susceptible strain in the laboratory. This study demonstrates that resistant strain indicates fitness costs when feeding on conventional cotton leaves. The larval survival rates of resistant strain were significantly lower than those of susceptible strain feeding on non-transgenic cotton (conventional parental cotton) DP5415 and Shiyuan321. However, when resistant Helicoverpa armigera fed on transgenic cottons (33B and SGK321), not only the larval survival rates were obviously higher than those of susceptible strain, but also its LT50s were extended than those of the latter. After feeding 9 days, the percentages of 4th and 3rd instar larvae of resistant strain fed on DP5415 and Shiyuan321 were significantly lower than those of susceptible strain, while the percentages of 3rd instar larvae of resistant strain were obviously higher than those of susceptible strain when they fed on 33B and SGK321. The pupal weights of resistant strain fed on conventional cottons were significantly lower than susceptible strain. Parts of resistant H.armigera could pupate after they fed on transgenic cotton, but there were no larvae could survive up to pupae in susceptible strain.