African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6693

Full Length Research Paper

Insecticidal activities and chemical composition of the essential oil from Tarchonanthus camphoratus (L.), leaves against Sitophilus zeamais Motschulsky, and Sitophilus oryzae (L.)

Sarah K. Nanyonga
  • Sarah K. Nanyonga
  • Department of Chemistry, University of Zululand, Private Bag X1001, KwaDlangewa, 3886, South Africa.
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Andy R. Opoku
  • Andy R. Opoku
  • Department of Bio-Chemistry and Microbiology, University of Zululand, Private Bag X1001, KwaDlangewa, 3886, South Africa.
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Francis B. Lewu
  • Francis B. Lewu
  • Department of Agriculture, Cape Peninsula University of Technology, Private Bag X8, Wellington, 7654, South Africa.
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Adebola O. Oyedeji*
  • Adebola O. Oyedeji*
  • Department of Chemistry and Chemical Technology, Walter Sisulu University, Private Bag X1, Mthatha, 5099, South Africa.
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  •  Received: 14 May 2012
  •  Accepted: 17 December 2014
  •  Published: 07 May 2015

Abstract

The essential oil of Tarchonanthus camphoratus dry leaves growing in Kwa-Zulu Natal, South Africa was obtained by hydrodistillation and evaluated for its repellent effect, contact and fumigation toxicity against both Sitophilus zeamais and Sarocladium oryzae. Chemical composition of the essential oil was analysed by gas chromatography mass spectrometry (GC/MS). The study revealed that the essential oil of T. camphoratus had no contact and fumigation toxicity against stored insect pests, S. zeamais and S. oryzae. The oil, however, showed good repellent activity of over 50% after 24 h for all the concentrations used on both S. zeamais and S. oryzae. A total of 27 compounds accounting for 73% of the total oil composition were identified of which sesquiterpene hydrocarbons, (59.18%), were the most dominant.  These results suggest that the essential oil of T. camphoratus could be considered a potential control agent of stored grain pests as a repellent.

 

Key words: Essential oil, chemical composition, Tarchonanthus camphoratus, Sitophilus zeamais, Sitophilus oryzae, fumigation, repellency, toxicity.