Acaricidal Activity and Synergistic Effect of Thyme Oil Constituents against Carmine Spider Mite (Tetranychus Cinnabarinus (Boisduval))

• Published in: Molecules (Basel, Switzerland) Vol. 22; no. 11; p. 1873
• Main Authors: Wu, Lipeng, Huo, Xin, Zhou, Xiaolong, Zhao, Duoyong, He, Weizhong, Liu, Shenghong, Liu, Hejiang, Feng, Ting, Wang, Cheng
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-11-2017; MDPI
• Subjects: Acaricides; Acaricides - chemistry; Acaricides - pharmacology; Agricultural production; Agrochemicals; Animals; Benzoic acid; Bioassays; botanical acaricides; Carmine - chemistry; Carmine - pharmacology; Carvacrol; Chemical composition; Constituents; Essential oils; Gas chromatography; Insecticides; Insects; Laboratories; Linalool; Mass spectrometry; Mass spectroscopy; Mites; Mixtures; Monoterpenes - chemistry; Monoterpenes - pharmacology; Mortality; Oils & fats; Oils, Volatile - chemistry; Oils, Volatile - pharmacology; p-Cymene; Pesticides; plant essential oil; Plant Oils - chemistry; Synergistic effect; Terpinene; Tetranychidae - drug effects; Thyme; thyme oil; Thymol; Thymol - chemistry; Thymol - pharmacology; Thymus Plant - chemistry; Toxicity; thyme oil; thymol; plant essential oil; botanical acaricides; synergistic effect
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules22111873

Studies examining the use of essential oils as replacements for synthetic insecticides require an understanding of the contribution of each constituent present, interactions among these components, and how they relate to overall toxicity. In the present study, the chemical composition of commercial thyme oil was identified by gas chromatography-mass spectrometry. Thyme oil and blends of its major constituents were tested for their acaricidal activitities against carmine spider mites (
) using a slide-dip bioassay. Natural thyme oil showed greater toxicity than any single constituent or blend of constituents. Thymol was the most abundant component (34.4%), and also possessed the strongest acaricidal activity compared with other single constituents. When tested individually, four constituents (linalool, terpinene,
-cymene and carvacrol) also had activity, while α-pinene, benzoic acid and ethyl gallate had almost no activity. The toxicity of blends of selected constituents indicated a synergistic effect among the putatively active and inactive constituents, with the presence of all constituents necessary to reach the highest toxicity. The results indicated that thyme oil and some of its major constituents have the potential to be developed into botanical acaricides.