Allelopathic, Phytotoxic, and Insecticidal Effects of Thymus proximus Serg. Essential Oil and Its Major Constituents

Shixing Zhou; Caixia Han; Chenpeng Zhang; Nigora Kuchkarova; Caixia Wei; Chi Zhang; Hua Shao

doi:10.3389/fpls.2021.689875

Allelopathic, Phytotoxic, and Insecticidal Effects of Thymus proximus Serg. Essential Oil and Its Major Constituents

Front Plant Sci. 2021 Jun 15:12:689875. doi: 10.3389/fpls.2021.689875. eCollection 2021.

Authors

Shixing Zhou^{1

2}, Caixia Han¹, Chenpeng Zhang^{1

2}, Nigora Kuchkarova^{1

3}, Caixia Wei^{1

2}, Chi Zhang⁴, Hua Shao^{1

2

3}

Affiliations

¹ State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, China.
² University of Chinese Academy of Sciences, Beijing, China.
³ Research Center for Ecology and Environment of Central Asia, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, China.
⁴ Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, College of Resources and Environment, Linyi University, Linyi, China.

Abstract

The chemical profile of Thymus proximus essential oil (EO) and its allelopathic, phytotoxic, and insecticidal activity was evaluated. Carvacrol, p-cymene, and γ-terpinene were detected as the major components of the EO, representing 85.9% of the total oil. About 50 g fresh plant material of T. proximus in a 1.5-L air tight container completely inhibited the seed germination of Amaranthus retroflexus and Poa anuua. Meanwhile, the EO exhibited potent phytotoxic activity, which resulted in 100% germination failure of both the test species when 2 mg/ml (for A. retroflexus) and 5 mg/ml (for Poa annua) oil was applied. The EO also triggered a significant insecticidal activity on Aphis gossypii with a LC₅₀ value of 6.34 ppm. Carvacrol was identified as the main active compound responsible for both the plant suppressing effect and the insecticidal activity of the EO. Our study is the first on the allelopathic, phytotoxic, and insecticidal activity of T. proximus EO, and the determination of the responsible compound, which indicated their potential of being further explored as environment friendly biopesticides.

Keywords: P-cymene; biopesticides; carvacrol; phytotoxicity; γ-terpinene.