RESUMEN
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.
RESUMEN
Gills of Maria-da-toca Hypleurochilus fissicornis collected at Ponta do Sambaqui-Florianópolis island-Brazil, were analyzed to describe the histopathology caused by metacercaria of Bucephalus margaritae. Gills were submitted to the routine histological techniques for embedding in paraffin and permanent mounting in Balsam and stereoscopic analysis. Metacercariae showed a branchial infection site pattern for encystations. The branchial infection site pattern is half-basalward in the primary branchial filament with amplitude of the infection of 1-3 metacercaria. Cysts occurred within branchial abductor muscle and cartilaginous and osseous tissues of the gills. Each metacercariae had a contentional hyaline parasitic capsule and melanin-like pigmentation. The half-apicalward region of the primary branchial filaments showed several dysplasia degrees, cartilage and osseous degeneration (pyknosis), thrombosis and immune exudated cells (mainly lymphocytes). Cytopathologies as thickening of the epithelium lining of the secondary branchial filaments were a response of the branchial infection site pattern of the metacercaria. Interlamellar obliteration and fusion of the lamellae due to the hypertrophy and hyperplasia of the epithelial lining as well as chloride cells occurred. Pyknosis of pillar cells and epithelial lining cells from the secondary branchial filaments were also present. Bucephalosis in H. fissicornis gills is no-hemorrhagic and no-fatal branchitis, but could compromises the gill functions and could permits the secondary opportunistic infections.
