Abstract: The individual genome DNA of male and female cotton bollworms (Helicoverpa armigera) was screened with RAPD-PCR technology by 500 random primers. A 450 bp marker amplified from female genome DNA with random primer Operon AF-18 was cloned and sequenced, which was confirmed as a specific molecular marker on the W chromosome. A part of HaKettin gene was cloned according to the sequences of homologues from Bombyx mori and Drosophila, and its copy number in the genome DNA of male and female cotton bollworms was detected with the real-time quantitative PCR technique compared with DH-PBAN. The ratio of copy between HaKettin and DH-PBAN was 1.0 in males and 0.5 in females, showing that the copy number of HaKettin is equal to that of Z chromosome in the genome of cotton bollworm. It is so inferred that HaKettin is located on Z chromosome in the genome of cotton bollworm.

Key words: Helicoverpa armigera, RAPD, molecular marker, sex chromosome, HaKettin gene