Structure and distribution of antennal sensilla in the Indianmeal moth, Plodia interpunctella (Hübner, 1813) (Lepidoptera: Pyralidae)

The Indianmeal moth, Plodia interpunctella, is an important primary pest of stored products worldwide. To better understand the chemical orientation of this insect towards its host products, we determined the structure and distribution of antennal sensilla of P. interpunctella by light and scanning electron microscopy (SEM). The results show that the antenna is filiform and made of three parts, a scape, a pedicel, and a flagellum. The female antenna was found slightly longer (5.20 ± 0.37 mm) than the male antenna (4.37 ± 0.23 mm). In both sexes, eight main types of sensilla were observed: Böhm bristles, sensilla basiconica, sensilla chaetica, sensilla coeloconica, sensilla styloconica, sensilla auricillica, sensilla squamiformia, and sensilla trichodea. The latter type was made of three subtypes according to their length: short sensilla trichodea, medium sensilla trichodea, and long sensilla trichodea. The sexual dimorphism in the antenna of P. interpunctella was mainly perceived as a variation in flagella length and sensilla distribution and size. External structure and distribution of these sensilla are compared to those of other pyralids and possible functions of the antennal sensilla are discussed.