Evaluation of acaricidal effect of terpinolene and γ-terpinene on Hyalomma anatolicum and in silico screening of herbs.

Abstract

Importance: Terpenoids of a plant origin are a class of alternatives to chemical acaricides for tick control. Despite this, few studies have evaluated the efficacy of terpenoid-containing herbal extracts or individual terpenoids in Hyalomma anatolicum.

Objective: This study evaluated the killing efficacy of terpinolene and γ-terpinene against H. anatolicum to identify herbs rich in these compounds as potential candidates for future materials in the control of H. anatolicum.

Methods: Terpinolene and γ-terpinene were subjected to adult tick immersion experiments to evaluate their killing effect on H. anatolicum, following their identification post-collection. The herbs were screened for the two terpenoids using the HERB database, and the resulting data were categorized and analyzed.

Results: The acaricidal effect of terpinolene and γ-terpinene against H. anatolicum showed a clear dose-response relationship, with effective doses LC₅₀ of 6.60 mg/mL and 4.86 mg/mL, respectively. In silico analysis revealed the presence of terpinolene and γ-terpinene in 52 and 36 herbs, respectively, with 16 herbs containing both compounds. These herbs could be grouped into 35 plant families. In particular, Lamiaceae and Apiaceae emerged as the most represented families, each accounting for 9.23% of the total herbs identified, followed by Zingiberaceae (7.69%) and Asteraceae and Rutaceae (6.15% each).

Conclusions and relevance: Terpinolene and γ-terpinolene have good killing effects against H. anatolicum. Herbs rich in the two terpenoids are promising candidates as plant-derived materials for managing H. anatolicum.