Synergistic interactions among the major constituents of lemongrass essential oil against larvae and an ovarian cell line of the cabbage looper, Trichoplusia ni
- 301 Downloads
Since plant essential oils are composed with vast numbers of constituents, they often show complex interactions among the components. Although the research interest on the insecticidal activity of plant essential oils has been gaining more attention recently, most of the studies still focus on simple screening of active plant source or identification of active compounds. In the present study, insecticidal activity and synergistic interactions among the four major constituents of lemongrass (Cymbopogon citratus) essential oil were examined via topical application against the third instar larvae of the cabbage looper, Trichoplusia ni. Two synergistic binary combinations—citral + limonene and citral + geranyl acetate—were identified at the equivalent mixing ratios. The former was especially synergistic in larvae and additionally with respect to cytotoxicity in the ovarian cell line of the cabbage looper. Morphological observations indicated different cytotoxic modes of action of citral and limonene. GC–MS analysis of larval extracts in vivo revealed several metabolites of citral and limonene, with geranic acid and neric acid (from citral), and limonene-1,2-diol (from limonene) as the major ones. The insecticidal activity of geranic acid was very similar to that of the parent compound, citral, but limonene-1,2-diol failed to show any toxicity, indicating that inhibition of the metabolism could be a good strategy to enhance toxicity. Further, larval extracts following topical administration of a binary mixture of the two compounds revealed higher internal concentrations of both compared to their individual application, suggesting the possibility of enhanced cuticular penetration as the mechanism of synergy.
KeywordsCitral Limonene Lemongrass oil Cabbage looper Synergy Botanical insecticide
The authors are grateful to Nancy Brad, Zyta Abramowski, and Lina Madilao for technical support.
The present study was funded by a University of British Columbia graduate fellowship (to JHT), a Discovery grant from the Natural Sciences and Engineering Research Council of Canada (NSERC; 2729-11)(to MBI), a Canada International Food Security Research Fund grant from the International Development Research Fund (IDRC; 106526)(to EJ), and a collaborative grant from Kittrich Corporation (to MBI).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Human rights statement
This article does not contain any studies with human participants performed by any of the authors.
- Belletti N, Kamdem SS, Tabanelli G, Lanciotti R, Gardini F (2010) Modeling of combined effects of citral, linalool and β-pinene used against Saccharomyces cerevisiae in citrus-based beverages subjected to a mild heat treatment. Int J Food Microbiol 136:283–289. doi: 10.1016/j.ijfoodmicro.2009.10.030 CrossRefPubMedGoogle Scholar
- Korenblum E, de Vasconcelos Goulart FR, de Almeida Rodrigues I, Abreu F, Lins U, Alves PB, Blank AF, Valoni E, Sebastián GV, Alviano DS, Alviano CS, Seldin L (2013) Antimicrobial action and anti-corrosion effect against sulfate reducing bacteria by lemongrass (Cymbopogon citratus) essential oil and its major component, the citral. AMB Express 3:44. doi: 10.1186/2191-0855-3-44 CrossRefPubMedPubMedCentralGoogle Scholar
- Miresmailli S, Bradbury R, Isman MB (2006) Comparative toxicity of Rosmarinus officinalis L. essential oil and blends of its major constituents against Tetranychus urticae Koch (Acari: Tetranychidae) on two different host plants. Pest Manag Sci 62:366–371. doi: 10.1002/ps.1157 CrossRefPubMedGoogle Scholar
- Shin S (2005) Anti-salmonella activity of lemongrass oil alone and in combination with antibiotics. Nat Prod Sci 11:160–164Google Scholar
- Tak JH, Jovel E, Isman MB (2016b) Comparative and synergistic activity of Rosmarinus officinalis L. essential oil constituents against the larvae and an ovarian cell line of the cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae). Pest Manag Sci 72:474–480. doi: 10.1002/ps.4010 CrossRefPubMedGoogle Scholar