Antenna and antennal sensilla dimorphism in Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Morphological studies on the antennae of Callosobruchus maculatus showed that the ratio of antennal length to body was almost double in the male compared to that of the female. Scanning with a light microscope and under dark field with polarized light revealed the presence of three types of sensilla (trichodea I, trichodea II, and basiconia) in both the sexes. Sensilla were radially arranged on the annuli of the antenna, and the number of sensilla of all types decreased from the distal to proximal annulus. However, the size of both the sensilla trichodea and the number of sensilla trichodea II was significantly greater in the male compared with the female, suggesting a possible sex pheromone detection role to the sensilla trichodea II in the male.