Dehydration is more effective for the control of embryonic development and larval hatching of Diplectanum aequans (Monogenea, Diplectanidae) than formalin and trichlorphon

Embryonic development and larval hatching of the monogenean Diplectanum aequans, gill parasite of sea bass Dicentrarchus labrax, was studied in relation to different prophylactic treatments. Groups of eggs of D. aequans were submitted to different in vitro treatments: formalin (300 and 100 μL L^sup -1^ per 1 hour), Neguvon^sup ®^ (trichlorphon 0.2 mg L^sup -1^ per 48 hours) and dehydration for 4 and 8 hours. Percentages of hatched larvae, aborted larvae and undeveloped embryos were estimated in comparison with the control group. Results showed that 300 μL L^sup -1^ formalin and dehydration treatments were able to reduce larval hatching significantly, while Neguvon^sup ®^ and 100 μL L^sup -1^ formalin treatments had no effect.[PUBLICATION ABSTRACT]