Ovicidal Potential of Five Different Essential Oils to Control Gastrointestinal Nematodes of Sheep

Abstract

The development of resistance to commercial anthelmintics, particularly in different species of gastrointestinal nematodes (GINs), requires the search for alternatives. Within that context, the aim of this study was to evaluate the in vitro ovicidal activity of five different essential oils (EOs): Origanum vulgare, Satureja hortensis, Thymus vulgaris, Mentha x piperita and Helichrysum arenarium against sheep GINs. For this purpose, the nematode eggs were collected from naturally infected sheep by GINs in two farms located in southern Italy. The egg hatch test (EHT) was performed at six different concentrations (50, 12.5, 3.125, 0.781, 0.195 and 0.049 mg/mL) for each EO. Gas chromatography-mass spectrometry chemical analyses of tested EOs, as well as coproculture examination of tested faecal samples, were also conducted. The results of EHT showed the greatest ovicidal activity of O. vulgare EO with a maximum effect on egg hatching (100%) for all tested concentrations. A similar effect was also shown by S. hortensis and T. vulgaris EOs with an activity of 99.3-100% and 98.5-100%, respectively. M. piperita EO showed medium, dose-dependent ovicidal activity with an inhibitory effect of 72.5-99.8% on the egg hatchability, while the least effective was H. arenarium EO with an activity of 59.8-69.3%. For the anthelmintic activities of the tested EOs are responsible their ingredients, above all carvacrol, thymol, p-cymene and gamma-terpinene. The present study demonstrated the significant anthelmintic potential of the tested EOs and emphasizes the possible importance of medicinal plant products for the control of gastrointestinal parasites in sheep.