The Propagation, Preservation Of Cryptocaryon Irritans Brown 1951, And Control Of Cryptocaryonosis

Cryptocaryon irritans (Brown, 1951) is an obligate parasite of marine fish living in tropical and subtropical zones, causing white-spot disease. Over years, the mariculture regions in South China have suffered white-spot disease severely, causing significant economic losses. We have studies on the propagation, preservation and integrated control of C. irritans in this thesis including following six parts: 1. A standardized method to propagate C. irritans on a susceptible host pompano Trachinotus ovatus ; 2. The developmental features of C. irritans after preservation in vitro at low temperature; 3. Killing efficacy of several chemotherapeutants against free living stage of ciliate C. irritans ; 4. Antiparasitic effect of several oral chemotherapeutants against infection of the ciliate C. irritans; 5. Immune response and immunoprotection of pompano against C. Irritans; 6. Passive immunisation of pompano against C. Irritans.A standardized procedure for C. irritans propagation was established by means of infecting the animal model pompano Trachinotus ovatus (167.8±15.1 g) with a sub-lethal dose of theronts. By using this method, up to 40 consecutive cycles were successively established. Briefly, theronts collected within 2 hr of excystment were used to infect pompanos (8,000-15,000 theronts per fish) in dark for 3 hr starting between 22:00-24:00, at 27±0.5 ℃ and 29-32 ‰ salinity. The trophonts on the skin and gill appeared evidently 60 hr post-infection. Their growth phase culminated when the mature trophonts spontaneously exited the host after another 24 hr and fell to the bottom as protomonts. All of the protomonts were collected by using a special collection unit. After a 60-hr incubation, the protomonts evolved into tomonts and began to release theronts. The excystment of theronts reached the peak after 24 hr, and...