Abstract
<jats:p>The study evaluated the ovicidal activity of Achillea setacea and Achillea micrantha extracts against strongylid eggs in in vitro experiments. The extracts were obtained from dried and ground herbs using an extraction method; the concentrated extracts were diluted in dimethyl sulfoxide (DMSO) to concentrations of 0.5% and 5%. A 4% phenol solution was used as a positive control, and untreated samples served as a negative control. The experiment was conducted on fresh horse feces. Samples were treated with extracts for exposure times of 30 and 60 minutes, as well as 24 and 48 hours. Assessment was performed using light microscopy (×400), taking into account morphological changes and egg viability. The results showed variable activity of the plant extracts. Exposure to 0.5% A. setacea (at all exposure times) and 5% for 30–60 minutes did not cause egg degeneration, and viable larvae were formed. For instance, after 30 minutes of exposure, egg viability was 98% (0.5%) and 95% (5%). However, 5% A. setacea extract after 24–48 hours of exposure caused signs of egg destruction (24 h – 77%, 48 h – 91%). Extracts of A. micrantha (0.5% and 5%) did not induce egg degeneration under any exposure regime, maintaining high viability and larval development. In the phenol-treated control samples, a rapid and pronounced effect was observed: viability suppression reached 57–58% after 30 minutes, 76–80% after 1 hour, and up to 96% after 24–48 hours. In the untreated control group, egg development proceeded normally. Thus, A. setacea exhibited a strong ovicidal effect of up to 91% at a 5% extract concentration and 48 hours of exposure, suggesting the potential use of Achillea setacea extracts at high concentrations and prolonged exposure to inactivate strongylid eggs in environmental settings.</jats:p>