Abstract:The morphology, especially the ultrastructures of antennal sensilla of B.tabaci was observed under scanning and transmission electron microscope. Antennae of B.tabaci are made up of scapus, pedicle and flagella that the latter consist of 1-5 segments and most of the antennal sensilla lie on its outer, upper and lower surfaces. Both the antennae of male and female contain five kinds of antennal sensilla, namely, microtrichia, chaetae sensilla, coeloconic sensilla, campaniform sensilla, basiconic sensilla, and the kinds, number and distribution of antennal sensilla of both sexes are similar. There have a large number of microtrichia and chaetae sensilla on the antenna of B.tabaci, and the number significantly higher than that of coeloconic, basiconic and campaniform sensilla, which was just 6, 4 and 1, respectively. Coeloconic sensilla and basiconic sensilla, the main chemical odor receptors on antennae of B.tabaci, consist of cuticular wall, sheath cells, sensillum lymph and dendrites. The role of olfactory function in the host-selection behavior of B.tabaci was investigated by Y-tube olfactometer. The result indicated 30% of B.tabaci adults have no response to the odor of host plants, but more than 50% of adults show the strongest host preference to piemarker, cotton, tobacco, cucumber and cabbage. There was significant difference on the orientation rate among the five host plants, followed by the order: cucumber>piemarker>cotton>tobacco>cabbage.