Ultrastructure of six types of antennal sensilla in Monochamus alternatus

Key Words：ultrastructure, sensillum, antenna, Monochamus alternatus, function

Abstract：      The ultrastructure of different types of antennal sensilla in Monochamus alternatus Hope was investigated by scanning and transmission electron microscopy. There were six types of sensilla on its antenna, i.e. mechanoreceptor, sensilla basiconica, sensilla trichodea, sensilla auricillica, sensilla chaetica and sensilla styloconica. There was thick wall and no dendrite in mechanoreceptor. There was thin cuticular wall perforated by numerous pores in sensilla basiconica, and more than 50 dendritic branches, each of which contained 1-10 microtubules. Sensilla trichodea were single\|walled with relatively fewer pores, and there were 1-8 dendrites, each of which contained different amount of microtubules. There was thin cuticular wall perforated by numerous pores in sensilla auricillica, and less than 5 dendritic branches, each of which contained different amount of microtubules. There were two subtypes in sensilla chaetica, in which subtype I showed grooved surface and no pores, but terminal pores, and subtype II showed no grooved surface and pores, as well as a terminal pore. There was thick non\|porous wall in both subtypes, and dendrite sheath up to terminal pore. There were lengthways veins and no pores on the upside of sensilla styloconica, several pores on the downside, and a trifurcate terminal pore. The functions of sensilla were discussed that mechanoreceptor was not chemical sensilla, and sensilla basiconica, sensilla trichodea and sensilla auricillica were olfactory sensilla, but sensilla chaetica and sensilla styloconica were possibly gustatory sensilla.