Dietary supplementation of garlic (Allium sativum) to prevent monogenean infection in aquaculture

Development of an effective preventative treatment for managing infections by Monogenea (Platyhelminthes) in aquaculture remains elusive. Present treatment methods offer only temporary respite and are either labor intensive, harmful to fish welfare or environmentally destructive. This study used garlic (Allium sativum) supplemented feed to assess its potential, in relation to its allicin content (an active component of garlic), to prevent infection by Neobenedenia sp. (Monogenea: Capsalidae) on farmed barramundi, Lates calcarifer. Two garlic supplemented diets of different concentrations and a non-supplemented control diet were fed to L. calcarifer for 10 and 30. days prior to challenging fish with Neobenedenia sp. Long-term (30. days) supplementation with garlic significantly reduced infection success by up to 70% compared to controls and did not negatively affect palatability of the feed. Infection success was not influenced by short-term (10. days) supplementation suggesting that a delayed host response must occur to improve resistance to infection. Incorporation of garlic into a pressure-extruded pellet was found to be an effective method of delivery as only minimal leaching of allicin from the diet occurred (<. 3% of allicin detected) during the interval of water contact between delivery and consumption. This study demonstrates that garlic extract administered as a dietary supplement is one of the most practical methods to prevent Neobenedenia sp. infection in mariculture. © 2013

Efficacy of garlic (Allium sativum) extract applied as a therapeutic immersion treatment for Neobenedenia sp. management in aquaculture

Garlic, Allium sativum L., extract administered as a therapeutic bath was shown to have antiparasitic properties towards Neobenedenia sp. (MacCallum) (Platyhelminthes: Monogenea) infecting farmed barramundi, Lates calcarifer (Bloch). The effect of garlic extract (active component allicin) immersion on Neobenedenia sp. egg development, hatching success, oncomiracidia (larvae) longevity, infection success and juvenile Neobenedenia survival was examined and compared with freshwater and formalin immersion. Garlic extract was found to significantly impede hatching success (5% ± 5%) and oncomiracidia longevity (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 Neobenedenia infection success of L. calcarifer to 25% ± 4% and 11% ± 4%, respectively, compared with 55% ± 7% in the seawater control. Juvenile Neobenedenia 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. © 2013 John Wiley & Sons Ltd