SPOROGONIC DEVELOPMENT OF THE GREGARINE ASCOGREGARINA-TAIWANENSIS (LIEN AND LEVINE) (APICOMPLEXA, LECUDINIDAE) IN ITS NATURAL HOST AEDES-ALBOPICTUS (SKUSE) (DIPTERA, CULICIDAE)

Sexual reproduction of Ascogregarina taiwanensis occurred in pupal Mal pighian tubules of its natural host Aedes albopictus, resulting in the formation of gametocysts within which oocysts developed. Sporogony pr oceeded in each newly formed unsporulated oocyst; eight sporozoites we re formed after completion of nuclear divisions followed by the cytoki nesis. Developing oocysts were separated by gradient centrifugation on percoll based on different buoyant densities. The slender sporozoite had a typical apical complex composed of a coiled conoid, polar rings, rhoptries with ductules, subpellicular microtubules and micronemes. A n apical cavity was seen in the gland-like rhoptries. Mitochondria of gregarines were not seen in any stage during the sporogony. However, a mylopectin granules were frequently seen in the cytoplasm. These starc h-related granules became scant when the sporozoite was formed. We ass umed they were associated with the energy source. Since the apical com plex was only present in the sporozoite stage, it was most likely rela ted to the invasion of host epithelial cells of the midgut during the early phase of infection.