STOMODAEAL VALVE ULTRASTRUCTURE IN THE SANDFLY LUTZOMYIA-LONGIPALPIS (DIPTERA, PSYCHODIDAE)

The stomodaeal valve and adjacent cardia region of the alimentary cana l of the phlebotomine sandfly Lutzomyia longipalpis have been studied using electron microscopy. With the scanning electron microscope (SEM) , numerous pit-like structures of different sizes were found in the su rface of the valve of male and female flies. Under the transmission el ectron microscope (TEM), the cells adjacent to the pores were shown to have numerous mitochondria and to lack neural innervation. It is sugg ested that the pit-like structures are probably secretory. A typical b asiconic sensilla was found on the inner side of the oesophagus at the junction with the stomodaeal valve, with at least one dendrite which extended to the tip, indicating a chemosensory role. It is likely that this type of sensilla may control the movement of the stomodaeal valv e after contact with fluids entering the mid-gut and may be responsibl e for diverting the sugar meal to the crop by closure of the valve.