A NEW SPORULATION SEQUENCE IN EDHAZARDIA-AEDIS (MICROSPORIDIA, CULICOSPORIDAE), A PARASITE OF THE MOSQUITO AEDES-AEGYPTI (DIPTERA, CULICIDAE)

The presence of a previously unrecognized sporulation sequence during the early development of the microsporidium Edhazardia aedis is descri bed from the mosquito, Aedes aegypti. This new information, together w ith the previous data on this species, has established that the develo pmental cycle of E. aedis is characterized by four sporulation sequenc es, two in the parental host and two in the filial generation. This is the first report of a microsporidium exhibiting four sporulation sequ ences. The events of gametogony, plasmogamy, nuclear association, and merogony occur almost exclusively in the gastric caeca following the i nitial infection and culminate with the formation of a first binucleat e spore. This spore is morphologically, ultrastructurally, temporally, and functionally different from the second binucleate (transovarial) spore. Our findings suggest that the first binucleate spore is respons ible for autoinfection and that its descendants lead to the formation of the second binucleate spore. (C) 1997 Academic Press.