Abstract
Garlic, A llium sativum L . , extract administered as a therapeutic bath was shown to have antiparasitic properties towards N eobenedenia sp. ( M ac C allum) ( Pl atyhelminthes: M onogenea) infecting farmed barramundi, L ates calcarifer ( B loch). The effect of garlic extract (active component allicin) immersion on N eobenedenia sp. egg development, hatching success, oncomiracidia (larvae) longevity, infection success and juvenile N eobenedenia survival was examined and compared with freshwater and formalin immersion. Garlic extract was found to significantly impede hatching success (5% ± 5%) and oncomiracidia longevity ( −1 , while eggs in the seawater control had >95% hatching success and mean oncomiracidia longevity of 37 ± 3 h. At much lower allicin concentrations (0.76 and 1.52 μL L −1 ), garlic extract also significantly reduced N eobenedenia infection success of L . calcarifer to 25% ± 4% and 11% ± 4%, respectively, compared with 55% ± 7% in the seawater control. Juvenile N eobenedenia attached to host fish proved to be highly resistant to allicin with 96% surviving 1‐h immersion in 10 mL L −1 (15.2 μL L −1 allicin) of garlic extract. Allicin‐containing garlic extracts show potential for development as a therapy to manage monogenean infections in intensive aquaculture with the greatest impact at the egg and larval stages.