Ultrastr ucture of the antennal sensilla on the funiculus of Bactrocera dorsalis is distinguished into two groups: the single-walled sensilla and the double-walled sensilla. The single-walled sensilla are further divied into those with thick-walled-pore and those with thin-walled-pore. The former have thick cuticular sensillar wall about 0.18-0.38 µm in thickness. The pore openings are small and the density of pores is only 11 to 12 pores per square micron. One or two dendrites appear in each sensillar lumen and they connect with one or two sensory cells. The latter have a thin cuticula r walls about 0.05-0.15 µm in thickness. The density of pores is about 25 pores per square micron . The pore openings are large with a circular pore below the cuticular wall. Twenty to sixty dendritic branches appear in the distal region of the sensillar lumen. In the clavate sensilla, besides the dendritic branches, there is a lamella or rolled dendritic structu re on the midregion of the sensillar lumen, with one or two sensory cells at the base of the sensilla, below the cuticular part. The double walled sensilla contains an original cuticul ar sensilla wall and 10 to 12 ridges to make a double walled structure which appears as a stellate structure in cross section . These sensilla include two sensory neurons and two to four dendritic branches in the sensillar lumen.
Ultrastructure, Thick-walled-pore sensilla, Thin-walled-pore sensilla, Double-walled sensilla
