Abstract:  Odour chemically mediates foraging, mating and oviposition behaviour of the tobacco cutworm, Spodoptera litura (Fabricius) (Lepidoptera, Noctuidae). The olfactory receptor is a direct receptor of odours and a key component of olfactory system, which plays an important role in encoding and transmission pathway of olfactory signal. By using RT-PCR and Western blot techniques, the tissue-specific expression of S. litura olfactory receptor gene Ⅱ(SlitOR2) (GenBank accession no. DQ845292) in different developmental stages was analyzed and identified. Semi-quantitative RT-PCR analysis indicated that SlitOR2 mRNA was mainly expressed in the adult antennae. Western blot result showed SlitOR2 was expressed mainly in the adult antennae, which was consistent with the previous semi-quantitative RT-PCR results. But there were also trace proteins which are expressed in the adult legs, head and midpupa. It could be the non-specific protein bands with similar size to target protein or the trace of proteins expressed in the adult legs, head and mid-pupa, because a small number of olfactory sensilla are distributed in both tarsi and proboscis. A clear single target band indicates that the obtained peptide antibody with high specificity can be used for further experiments.

Key words: Spodoptera litura; olfactory receptor, semi-quantitative RT-PCR, Western blot, gene expression profile