G. Schmahl, TREATMENT OF FISH PARASITES .10. EFFECTS OF A NEW TRIAZINE DERIVATIVE, HOE-092-V, ON MONOGENEA - A LIGHT AND TRANSMISSION ELECTRON-MICROSCOPY STUDY, Parasitology research, 79(7), 1993, pp. 559-566
For chemotherapy of fish parasitized by monogeneans, a novel triazine
derivative, phenyl]-1-methyl-hexahydro-1,2,4-triazine-3,5-dion (HOE 09
2 V), was tested in vivo against the gill- and skin-parasitizing speci
es Dactylogyrus extensus, D. vastator, and Gyrodactylus arcuatus. Natu
rally infected fish were incubated in aerated, separate tanks at 22-de
grees-C for 1, 2, 3, and 4 h in water containing 0, 1, 5, 10, or 15 mu
g HOE 092 V/ml, whereas Pseudodactylogyrus bini was tested in vitro at
10 mug HOE 092 V/ml for 2.25 h. As seen by means of transmission elec
tron microscopy, in vivo treatment against D. extensus caused vacuoliz
ation and lysis of the parasite's tegument at a dose as low as 1 mug/m
l over a 3-h exposure period. Higher doses, such as 5 and 10 mug/ml ov
er the same exposure period, produced lesions in the circular and long
itudinal musculature of D. extensus and differing degrees of damage to
the ciliary cells of protonephridia and immature vitelline cells. The
re was 100% mortality in D. vastator when incubation was done with 10
mug HOE 092 V/ml for 4 h (G. arcuatus: 5 mug/ml for 4 h; 10 mug/ml for
1 h) and in P. bini after 2.25 h in vitro exposure. In all species te
sted, the anterior portion and the opisthaptor region were most sensit
ive to the drug action. This study shows that fish infected with Gyrod
actylus spp., Dactylogyrus spp., and/or Pseudodactylogyrus spp. can be
treated successfully in a water bath containing 10 mug HOE 092 V/ml.