Chemical profiles, acaricidal activity, and enzymatic and transcriptomic mechanisms of Cinnamomum tamala essential oil and cinnamaldehyde against Hyalomma asiaticum

Hyalomma asiaticum , a Palearctic species of significant medical and veterinary relevance, has been identified as a primary vector for Crimean-Congo hemorrhagic fever, Q fever, spotted fever, Tick-borne Encephalitis, Theileriosis, and Anaplasmosis. This study evaluated the efficacy of Cinnamomum tamala EO in controlling ticks through transcriptomic analysis and enzymatic assays. Gas chromatography–mass spectrometry revealed that cinnamaldehyde is the principal component of C. tamala EO. Larval packet tests demonstrated that C. tamala EO exhibited significant acaricidal activity against unfed larvae of H. asiaticum . Immersion tests indicated that both C. tamala EO and cinnamaldehyde displayed considerable acaricidal effects on unfed nymphs and adults of H. asiaticum . Enzymatic assays showed that cinnamaldehyde significantly inhibited carboxylesterase activity while enhancing acetylcholinesterase levels. This research focuses on short-term transcriptomic alterations analyzed via RNA sequencing in H. asiaticum following treatment with C. tamala EO, aiming to identify differentially expressed genes post-treatment with this essential oil. Notably, flavin monooxygenase was significantly upregulated after exposure to C. tamala EO; results from RT-qPCR corroborated those obtained from transcriptome sequencing analyses. These findings suggest that FMOs are implicated in the detoxification mechanisms employed by H. asiaticum in response to C. tamala EO treatment which may help mitigate the development of acaricide resistance among ticks, indicating that C. tamala EO could serve as an effective alternative to synthetic chemical acaricides.