Antennal Sensilla Ultrastructure in Aphidius gifuensis (Hymenoptera: Braconidae), A Parasitoid of Myzus persicae (Hemiptera: Aphididae)

Aphidius gifuensis Ashmaed (Hymenoptera: Braconidae) is an important aphid parasitoid species of the green peach aphid, Myzus persicae (Sulz.) For better comprehend the host discrimination mechanism of this parasitoid, the ultrastructure, abundance and distribution of antennal sensilla of A. gifuensis male and female were examined using scanning electron microscope. The antenna has a filamentous shape, comprised of radicula, scape, pedicel, and flagellum. Six kinds of antennal sensilla were found in A. gifuensis, including sensillum chaetica, s. trichode, s. basiconica, s. coeloconicum I, s. coeloconicum II and s. placodea. Sexual differences were found in length of antennae and rate of abundance of several sensillum types. The length of female antenna is much longer than that of males. S. placode and s. trichode are of higher density in male in comparison to those in females. On contrary, s. basiconica are more in females than males. The ultrastructure of all sensillum types of A. gifuensis male and female were compared to those found on other hymenopteran parasitoid species, particularly braconids. The probable roles of these sensillum types in the courtship and host discrimination of A. gifuensis were discussed.