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 (RTPCR) 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 RTPCR showed that the ScerOrCo mRNA was expressed specifically in adult antennae and had no difference between female and male (P>0.05).