Abstract: 【Aim】 To clarify the types, morphology, quantity and distribution of sensilla on the female and male adult antennae of Cotesia ruficrus, an indigenous parasitic natural enemy against Spodoptera frugiperda, a major invasive agricultural pest, and provide theoretical support for exploring the function and olfactory mechanism of various types of sensilla of C. ruficrus.【Methods】 The sensilla on female and male adult antennae of C. ruficrus were observed with scanning electron microscope. 【Results】 The subsegments of antennal flagellum of the male adult of C. ruficrus are long moniliform, and the distal 5 segments of the antennae of female adults are short moniliform. The total length of the male antennae is significantly longer than that of the female. Eleven types of sensilla including Böhm’s bristles, sensilla trichodea, sensilla placodea, sensilla basiconica, sensilla chaetica, sensilla coeloconica, sensilla campaniformia, sensilla squamous, sensilla gemmiformia, sensilla cavity and sensilla cylindric, and smell pores were found on female and male adult antenna. Among them, sensilla trichodea, sensilla placodea and sensilla basiconica have two subtypes. Sensilla trichodea and sensilla placodea are the main sensilla on the antennae of C. ruficrus, with a wide distribution and a large number. Sensilla cavity are only distributed in pairs on the pedicel, and sensilla cylindric were only found on the flagellum of male adult. Sensilla gemmiformia were found for the first time in Braconidae.【Conclusion】We identified eleven types of antennal sensilla in female and male adults of C. ruficrus, more than those in other known braconid species, and sensilla gemmiformia were found for the first time in braconid species, speculating that they may play an important role in host positioning and searching for spouses.

Key words:  Cotesia ruficrus, adult antenna, sensillum, scanning electron microscope, ultrastructure