To clarify the role of phospholipase C (PLC) in insect olfactory transduction, we have undertaken its molecular identification in the moth Spodoptera littoralis. From the analysis of a male antennal expressed sequence tag library, we succeeded in cloning a full-length cDNA encoding a PLC that belongs to the cluster of PLC-b subtypes. In adult males, the PLC-b transcript was located predominantly in brain and antennae where its presence was detected in the olfactory sensilla trichodea. Moreover, PLC-b was expressed in antennae at the beginning of the pupal stage, then reached a maximum at the end of this stage and was maintained at this level during the adult period. Taken together, these results provided molecular evidence for the putative participation of a PLC-b in signaling pathways responsible for the establishment and the functioning of insect olfactory system.