Scanning Electron Microscopy of Antennal Sensilla of the European Corn Borer, Ostrinia nubilalis1

Abstract

Scanning electron microscopy of the antennae of Ostrinia nubilalis (Hubner) moths was used to compare morphological classes and numbers of external sensilla typical of the sexes. These observations are correlated with previous studies of sex pheromone receptor sensilla in Bombyx mori L. for assessment of the physical apparatus responsible for sex pheromone detection in the corn borer. Sensillar classes found on antennae of both male and female corn borers include sensilla styloconica, sensilla chaetica, sensilla coeloconica, sensilla auricillica, sensilla basiconica, and sensilla trichodea. The sensilla trichodea are further subdivided into two distinct types (designated A and B) on criteria of surface substructure and length. Sensilla trichodea are more numerous on the antennae of male moths than on those of females, with the excess surface area of Type A sensilla trichodea estimated at 100% greater in the males. Estimates of numerical totals and distribution along the antennal flagelluni are compared for the sensilla trichodea types for both sexes. The other sensilla of male and female corn borer moths also have been compared with respect to location on the antennae and relative frequency. Complete descriptions of sensillar and antennal morphology as observed with this technique are included.