In order to better understand the roles of cysteine proteinase gene and develop a novel molecular target for insect pest control

we obtained the full-length cDNA sequence of Bdcyp (GenBank accession no. KU904503) from the oriental fruit fly

Bactrocera dorsalis (Hende) by using RT-PCR and RACE methods. The deduced amino acid sequence analysis of Bdcyp was performed by using bioinformatics methods. The expression patterns of Bdcyp in different stages and tissues were investigated using quantitative real-time PCR (qPCR). The Bdcyp was 1 955 bp in lenght

containing an open reading frame of 1 653 bp which encodes 551 amino acid residues with a predicated molecular weight of 62 900 and isoelectric point of 6.11. Bdcyp had typical features of cysteine proteinase

including signal peptide

three catalytic active regions (Cys-His-Asn)

and two conserved motifs (ERFNIN and GNFD). Phylogenetic analysis showed that Bdcyp has the closest genetic relationship with the cysteine proteinase of B. oleae. Bdcyp was constitutively expressed in the tested stages

including third-instar larvae

pupae and adults. The highest expression level was observed at the middle of pupal stage. Tissuespecific expression showed that the highest expression was in the fat body

followed by trachea and integument

and the expression in midgut was the lowest. The results provide the basis for further studying the function of Bdcyp.