In vitro Assessment of the Acaricidal Activity of Laurus nobilis and Croton tiglium Seeds Extract against Hyalomma dromedarii Ticks

Abstract

Background: Ticks are destructive ectoparasites that feed on the blood of domestic animals and the spread of ticks causes significant losses in meat, milk and leather production. About 800 species of ticks are known around the world, Hyalomma dromedarii is one of the ticks that attack camels as their main host. The objective of this study was to identify the acaricidal activity of Laurus nobilis and Croton tiglium seeds extract against H. dromedarii ticks and comparison with some drugs used against external parasites. Methods: A study was performed to evaluate the acaricidal activities of methanolic extracts of two medicinal plants, namely the seeds of C. tiglium and L. nobilis, against H. dromedarii using an adult immersion test and larval bundle test. Five graduated concentrations of extracts, 6.25, 12.5, 25, 50 and 100 mg/ml, were tested at different periods and changes over time in the viability of ticks were registered for 24 hr. Distilled water and cypermethrin (0.1%) were used as a negative and positive control, respectively. Result: From 30 min after exposure, a concentration of 100 mg/ml of C. tiglium seed extract resulted in higher mortality (p less than 0.05) compared with cypermethrin. A significant rise in tick mortality began 2 hr after exposure to a concentration of 100 mg/ml of C. tiglium seed extract and cypermethrin. At 24 hr after exposure, cypermethrin and concentrations of 50 and 100 mg/ml of C. tiglium extract induced significantly higher tick mortality compared to the rest of the concentrations. A significant increase in tick mortality began 3 hr after exposure to cypermethrin and concentrations of 50 and 100 mg/ml of Laurus nobilis extract and 12 hr after exposure to concentrations of 6.25, 12.5 and 25 mg/ml L. nobilis extract. At 24 hr after the exposure time, concentrations of 50 and 100 mg/ml of the extract and cypermethrin had a comparable higher tick mortality effect compared to the remaining concentrations below 25 mg/ml (p less than 0.05). The lower concentration (6.25 mg/ml) resulted in notably higher mortality of adult ticks and larvae compared to the negative control (distilled water) at 24 hr exposure to both extracts. At 24 hr after the exposure period, the tick mortality of all estimated plant extracts also increased with raised exposure time and concentration. Therefore, studied plants can be used against H. dromedarii as a potential alternative to commercially available medicines. Further studies should include more research on separating each component and validating the materials.