Abstract: The structure and olfactory function of antennal sensilla of the bean pod borer Maruca testulalis (Geyer) (Lepidoptera: Pyralidae) were investigated by the scanning electron microscopy (SEM) and electroantennogram (EAG) technology. The results showed that there are five types of sensilla in both male and female antenna，including sensilla trichodea，sensilla chaetica，sensilla coeloconicum，sensilla auricillica and sensilla styloconicum， whereas another type of sensilla，sensilla cylindric，was observed only in the male antenna. The number of all types of sensilla in both male and female adults was statistically analyzed by dividing the antenna into three sections (basal， middle and distal). It was found that the quantity of sensilla was significantly different between male and female in three types of sensilla (sensilla trichodea， sensilla coeloconicum and sensilla auricillica). The EAG responses of male and female adults to sex pheromone，(E10， E12)-hexadecadienal and (E10， E12)-hexadecadien-1-ol，and plant volatiles，cis-3-hexenyl acetate and (l)-linalool，showed no correlation between the number of sensilla and the EAG amplitude. The sensilla contributed to the sensory responses to pheromone compounds are mainly distributed in 24 distal flagellar segments of the antenna (1/3)， but the segments detecting the plant volatiles are distributed in 48 distal flagellar segments of the antenna (2/3)．

Key words: Maruca testulalis, antennal sensilla, SEM, EAG, plant volatiles, sex pheromone