Antiparasitic potential of alternative treatments against larval stages of Lernaea cyprinacea

This study evaluated the potential of alternative treatments against larval stages of Lernaea cyprinacea. For in vitro test, the nanoemulsified oils of Pinus sp. acicule and oleoresin were evaluated, along with Biogermex® (commercial product based on citrus biomass). For this, the motility of five larvae of the same stage (nauplii or copepodite) were evaluated in a 96-well microplate. Using the best results, on the in vivo test, fries of Rhamdia quelen were submitted to a long-term immersion bath (96 h) containing different concentrations of the product diluted directly in the water. It was possible to notice the antiparasitic potential of the oleoresin and the acicule of Pinus sp., as well as the citrus biomass extract against the parasites. The nanoemulsified oils successfully inhibited the development of nauplii (10 mg L⁻¹ in 24 h) and the fries showed to be tolerant to the presence of the compound (LC₅₀ 96 h—16.74 mg L⁻¹). The concentration of 30.5 mg L⁻¹ of Biogermex® eliminated the copepodites within 24 h, being more efficient than Pinus sp. when tested at the same stage, at the times analyzed. The results obtained indicate a potential use of these compounds as prophylactic agents against L. cyprinacea.