In vitro acaricidal activity of essential oil and alcoholic extract of Trachyspermum ammi against Dermanyssus gallinae

This study aimed to assess in vitro acaricidal activity of essential oil (EO) and alcoholic extracts (AE) of Ajowan against D. gallinae. Using contact and spraying bioassays, different doses of EO and AE were tested. Cypermethrin and thymol (positive controls), and ethanol and distilled water (negative controls) were also tested. The results indicated that effects were method and dose dependent. Statistical analysis showed a highly significant difference for contact and spraying bioassays and various doses of EO and AE (p < 0.0001) as, the spraying method was more effective than the contact method for acaricidal activity at 24 h post treatment (PT). In this method, Cypermethrin, EO and thymol caused over 90 % mite mortality at 50 μgcm⁻², while AE caused this rate at 150 μgcm⁻². In the contact bioassay, all tests produced low mortality rates except for Cypermethrin. Thymol was the main constituent of EO (Area = 42.26 %) and AE (Area = 45.8 %). Results of the present study indicated that Ajowan had a satisfactory acaricidal effect against D. gallinae in vitro. It was also found that the spraying method could be used to control the D. gallinae as the most appropriate method.