In the present study,the fulllength cDNA of the odorant receptor coreceptor gene was cloned from the antennae of Sitotroga cerealella (named ScerOrCo) by using reverse transcription polymerase chain reaction (RTPCR) and rapid amplification of cDNA ends (RACE).Sequence analysis revealed that the transcript consisted of 1 876 nucleotides and the open reading frame was 1 422 bp,encoding a peptide of 437 amino acids with 7 putative transmembrane domains.The deduced amino acid sequence of ScerOrCoshared the highest similarity with the olfactory receptor of Mythimna separate (87%).The results of quantitative real time RTPCR showed that the ScerOrCo mRNA was expressed specifically in adult antennae and had no difference between female and male (P＞0.05).