In vitro anthelmintic effect of plant extracts on gastrointestinal nematodes of hair sheep

Abstract

Due to the growth of resistance of the gastrointestinal nematodes (GIN) to the anthelmintic ones, it was proposed as a goal to evaluate in vitro the efficacy of essences from different plants. There were formulated hydro-alcoholic essences that were put on over eggs and infective larvae (L3) of GIN. In the case of the larvae, there were carried two tests: in the first one, there were used gourd essence (L. diversifolia), black Elephant’s ear (E.cyclocarpum) and pega-pega (D. tortuosum); whereas for the second bioassay, there were used gourd essence (L. Leucocephala), mangrove (R. mangle) and neem (A. indica). In the inhibition test of the hatching of eggs (ITHE), there were used neem leaves (A. indica), yerba santa leaves (P. auritum) and skunk weed leaves (P. alliacea).

Eggs and larvae were obtained from infected ovine in a natural way while grazing. The infective larvae were unsheathed with sodium hypochlorite (0.187%). After, there were added 100 larvae per pit on distilled water and they challenged themselves with their essence through an in vitro test of larval motility with direct observation. Treatments were the essen­ces at different concentrations (100, 50, 25, 12.5, 6.25, 3.13, 1.56, 0.78, 0.39, 0.20, 0.10, 0.05 mg/ml-1). The levamisole on its commercial and diluted presentation (120, 60, 30, 15, 7.5, 3.75, 1.88, 0.94, 0.47, 0.23, 0.12, and 0.06 mg/ml-1) was used as a reference to determine the effectiveness of the essences and the larvae in distilled water to determine the natural mortality. In the ITHE test, there were also used the same concentrations. Data were analyzed through the process PROBIT. The re­sults demonstrated that the essences of L. leucocephala and A. indica presented a stage of larvicidal action in GIN similar to levamisole. With the essence of L. leucocephala, there was obtained the least lethal dose (DL50=0.045mg/ml-1) against L3. In the hatching of eggs, the best results were obtained with the essence of P. alliance and P. auritum.