Bio-efficacy of Syzygium aromaticum bud extract as eco-friendly green acaricide for controlling Hyalomma dromedarii.

The most common hard tick in Egypt is Hyalomma dromedarii as a one of the most dangerous ectoparasites. The current study aims to detect the chemical composition of Syzygium aromaticum bud ethanolic extract using GC-MS and some phytochemical analysis in addition to investigating its acaricidal activity on H. dromedarii engorged females through biological and biochemical studies. The GC-MS revealed the presence of eugenol, eugenol acetate and D-(-)-fructofuranose as the most active compounds, and it appeared to be rich in alkaloids, flavonoids, phenolic compounds, tannins and terpenoids. At high concentration, the extract caused mortality to reach 100% after 35 days of treatment in engorged females, with LC50 reached 100.22 and 0.83 mg/mL after the 3rd and 5th week (half and end of examined period) following treatment, respectively. The blood digestion was affected by significantly decreasing in their body weights. Furthermore, the extract showed a decrease in their oviposition, hatchability, and fertility. The extract at 100 mg/mL caused a reduction in ovary total protein content with disappearance of some protein bands using SDS-PAGE, compared with the control group. Overall, the current study revealed the effectiveness of S. aromaticum extract as a bio-acaricide for controlling H. dromedarii and it recommended numerous additional field studies to assess its effectiveness under different conditions.