Antiparasitic efficacy of essential oils for Neobenedenia melleni infecting farmed Lebranche mullet (Mugil liza)

The present study investigated the phytotherapeutic effects of Lippia origanoides, L. sidoides and Mentha piperita (100, 200, 300, 400, 500, 600 and 700 mg L^–1) and the chemotherapeutics formalin (100, 200, 300, 400, 500, 600 and 700 mg L^–1), potassium permanganate (1.5, 2.5, 3.5, 4 and 5 mg L^–1), hydrogen peroxide (90, 180, 200, 250, 300 and 350 mg L^–1) and salinity (0.5 and 10.0 g L^–1) on Neobenedenia melleni infecting cultivated Mugi liza. The parasites were collected from 15 individuals of a first-generation broodstock of aquacultured mullets with average weights and lengths of 900.4 ± 96.99 g and 45.67 ± 1.50 cm, respectively. In vitro assessments were conducted in triplicate in experimental units consisting of polystyrene plates with flat bottoms, smooth surfaces and high edges containing 10 parasites in each well. For quantification of dead parasites and behavioral observations, treatments were monitored at different exposure times (5, 10 and 15 min) and then every 30 min. Treatments involving essential oils were effective for ectoparasite immobilization. The treatments with 100% effectiveness in the shortest time were 600 and 700 mg L^–1 L. origanoides (1 min), followed by L. sidoides at 700 mg L^–1 (4 min) and M. piperita at 700 mg L^–1 (9 min). Formalin, hydrogen peroxide, potassium permanganate, and freshwater baths were also effective against N. melleni. The present study indicates that sanitary treatments with essential oils and freshwater baths for N. melleni infecting the Lebranche mullet M. liza are highly sustainable and pose a low risk to the environment. © The Author(s) 2024.