Experiments on the Evaluation of the Blood Feeding of Heterobothrium okamotoi (Monogenea : Diclidophoridae)

Blood feeding of the monogenean Heterobothrium okamotoi from tiger puffer Takifugu rubripes was examined. Physiological saline containing fluorescent microspheres (1μm in diameter) was injected into the hepatic vein of one-year-old tiger puffer experimentally or naturally infected with H. okamotoi, and blood was taken from the host at 3 and 12 h post-injection (PI). Parasites were collected at 12 h PI and individually digested with KOH. Microspheres in the host blood and parasite body were counted by fluorescence microscopy. The amount of blood taken by individual parasites was calculated by the number of microspheres in the parasite body divided by the mean value of the microsphere concentration in the host blood at 3 and 12 h PI. The results show that the amount of blood increased as the parasite developed and that anadult fed 0.69±0.93μL of host blood for 12 h (=42μL/month). This is the first report of a quantitative study on the blood feeding of polyopisthocotylean monogeneans.