Abstract: Olfactory receptors (ORs) play a critical role in insect olfactory system. Research on ORs can help us understand the molecular mechanism of odors discrimination in insect. In this study, 11 Helicoverpa armigera OR genes (GenBank accession numbers: EU599565-EU599568, EU818702-EU818706, FJ393455) were cloned using RT-PCR. The results of sequence analysis showed that HarmOR2 was atypical OR and the rest 10 ORs were typical ORs. Phylogenetic tree indicated that HarmOR10 and DOr46a belonged to a single cluster, while HarmOR4 belonged to a cluster of gustatory receptors (Grs). The other H. armigera ORs belonged to the cluster which had a long distance with Drosophila melanogaster ORs. We also found that HarmOR2 was expressed in antennae and proboscis of H. armigera, while other HarmORs were specially expressed only in the antenna of adult moth, of which HarmOR3，HarmOR13 and HarmOR14 were expressed only in the antenna of male adult. Moreover, HarmOR12 and HarmOR20 were expressed at higher level in antenna of male than that of female, while other HarmORs were expressed at the same level both in female and in male.

Key words: Helicoverpa armigera, olfactory receptors, RT-PCR, cloning, expression pattern