Effect of essential oils on cattle gastrointestinal nematodes assessed by egg hatch, larval migration and mortality testing

Abstract

AbstractThe efficacy of eight essential oils (EOs) (Solidago canadensis,Eucalyptus globulus,Pelargonium asperum,Ocimum basilicum,Thymus vulgaris,Mentha piperita,Cymbopogon citratusandCymbopogon martinii) against gastrointestinal nematodes (GINs) was evaluated using eggs collected from naturally infected cattle and cultured infective larvae (L3). The larvae species cultured from the faecal samples and subjected to twoin vitrotests wereHaemonchusspp. (55.5%),Trichostrongylusspp. (28.0%),Cooperiaspp. (15.0%) andOesophagostomumspp. (1.5%). The genus of EOCymbopogon(C. citratusandC. martinii) showed the highest anthelmintic activity at the dose of 8.75 mg/ml, for the egg hatch, the larval migration and mortality assays. All of the EOs tested reduced egg hatching to rates <19.0%, compared to the controls (water and water + Tween 20) that had rates >92.0%.Cymbopogon citratusandC. martiniitreatments resulted in 11.6 and 8.1% egg hatch, had the lowest migration of larvae through sieves, 60.5 and 54.9%, and the highest mortality rates, 63.3 and 56.3%, respectively. Dose–response tests showed that EO fromC. citratushad the lowest larval LC50and migration inhibition concentration (IC50) values of 3.89 and 7.19 mg/ml, respectively, compared to two other EOs (C. martiniiandO. basilicum). The results suggest that EOs from the genusCymbopogoncan be interesting candidates for nematode control in cattle, although it may prove challenging to deliver concentrations to the gastrointestinal tract sufficient to effectively manage GINs.