Contact, fumigant, and cytotoxic activities of thyme and lemongrass essential oils against larvae and an ovarian cell line of the cabbage looper, Trichoplusia ni

Abstract

The chemical composition of a plant essential oil can be affected by many environmental and biological factors. Understanding the role of individual constituents as well as their interactions to the overall insecticidal bioactivity is prerequisite to the use of essential oils as an alternative to conventional insecticides. In the present study, the chemical compositions of plant essential oils obtained from Thymus vulgaris (thyme) and Cymbopogon citratus (lemongrass) were analyzed by gas chromatography/mass spectrometry, and the insecticidal and cytotoxic activities of individual constituents were evaluated against third instar larvae and an ovarian cell line of Trichoplusia ni. Thymol was the most abundant compound in thyme oil and the primary active constituent in contact and cytotoxicity tests, whereas p-cymene was the most effective compound for fumigant toxicity. In lemongrass oil, citral was identified as the major active and most abundant constituent. A weak correlation between insecticidal activity and cytotoxicity was observed, indicating limitation of the latter as a screening tool for novel insecticides. Although the evaporation of thymol was enhanced at higher temperatures, its contribution to fumigant activity was limited.

Insecticidal Activity of Melaleuca alternifolia Essential Oil and RNA-Seq Analysis of Sitophilus zeamais Transcriptome in Response to Oil Fumigation

“…However, it is difficult to compare data due to different concentrations of essential oils used for the same insect, S . zeamais [15], or different pest insects used [46, 47]. Similar to the previous study [15], the fumigant effect of plant essential oil in S .…”

Insecticidal and acetylcholinesterase inhibitory activities of Lamiaceae plant essential oils and their major components against Drosophila suzukii (Diptera: Drosophilidae)

“…Seo et al (2010) reported that alcohols were more effective than hydrocarbons for nematocidal activity. Thymol and carvacrol have been reported to have contact toxicity against insects and mites (Yeom et al, 2012;Kim et al, 2015;Tak et al, 2016). p-Cymene alone did not show effective fumigant toxicity against Japanese termite, Reticulitermes speratus (Isoptera: Rhinotermitidae) and Lycoriella ingenua (Diptera: Sciaridae) (Park et al, 2008;Seo et al, 2009).…”

In vitro Antifungal Activity of Essential oils and Major Components against Fungi Plant Pathogens

“…On the other hand, quantitative and qualitative composition variations of lemongrass EO were identified in other studies, such as Tak et al. () who reported C. citratus EO chemical composition as geranial (46%), neral (30%) and geraniol (2.5%). Meanwhile, Adukwu et al.…”