title: Repellent effects of the essential oils of Cymbopogon citratus and Tagetes minuta on the sandfly, Phlebotomus duboscqi.
abstract: BACKGROUND
  The sandfly, Phlebotomus duboscqi is a vector of zoonotic cutaneous leishmaniasis (ZCL) that is an important public health problem in Eastern Africa. Repellents have been used for protection of humans against vectors of ZCL and other vectors that transmit killer diseases including malaria, Rift Valley fever, dengue, and yellow fever. The repellent effects of different doses of the essential oils from the lemon grass, Cymbopogon citratus and Mexican marigold, Tagetes minuta were evaluated in a two-chamber bioassay against 3- to 7-day-old unfed females of P. duboscqi in the laboratory. The results were compared with those that were obtained when test animals were treated with an equivalent dose of diethyl-3-methylbenzamide, which is a repellent that is commonly used as a positive control.
  
  
  RESULTS
  Overall, percentage repellency increased with increasing doses of the essential oils while biting rates decreased with increasing concentrations of the oils. Further, the oil of C. citratus was more potent than that of T. minuta with regard to protection time and biting deterrence. The effective doses at 50% (ED50) and at 90% (ED90) for the oil of C. citratus, were 0.04 and 0.79 mg/ml, respectively. Those of the oil of T. minuta were 0.10 and 12.58 mg/ml. In addition, the percentage repellency of 1 mg/ml of the essential oils of C. citratus and T. minuta against sandflies was 100% and 88.89%, respectively. A lower dose of 0.5 mg/ml of the oils, elicited 89.13% repellency for C. citratus and 52.22% for T. minuta.
  
  
  CONCLUSIONS
  The laboratory tests showed that the essential oils of the two plants were highly repellent to adult sand flies, P. duboscqi. Thus, the two essential oils are candidate natural repellents that can be used against P. duboscqi due to their high efficacy at very low doses, hence, the envisaged safety in their use over chemical repellents. It remains to carry out clinical studies on human subjects with appropriate formulations of the oils prior to recommending their adoption for use against the sandflies.
authors.affiliation: Department of Biological Sciences, University of Kabianga, P.O. Box 2030-20200, Kericho, Kenya. kimutaialbert@yahoo.com.
authors.forename: Albert
authors.initials: A
authors.lastname: Kimutai
authors.affiliation: University of Eldoret, P.O. Box 1125-30100, Eldoret, Kenya.
authors.forename: Moses
authors.initials: M
authors.lastname: Ngeiywa
authors.affiliation: University of Eldoret, P.O. Box 1125-30100, Eldoret, Kenya.
authors.forename: Margaret
authors.initials: M
authors.lastname: Mulaa
authors.affiliation: Department of Biological Sciences, University of Kabianga, P.O. Box 2030-20200, Kericho, Kenya.
authors.forename: Peter G N
authors.initials: PG
authors.lastname: Njagi
authors.affiliation: Center for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. BOX 54840 - 00200, Mbagathi Rd., Nairobi, Kenya.
authors.forename: Johnstone
authors.initials: J
authors.lastname: Ingonga
authors.affiliation: Moi University, P.O. Box 3900-30100, Eldoret, Kenya.
authors.forename: Lydia B
authors.initials: LB
authors.lastname: Nyamwamu
authors.affiliation: Department of Biological Sciences, University of Kabianga, P.O. Box 2030-20200, Kericho, Kenya.
authors.forename: Cyprian
authors.initials: C
authors.lastname: Ombati
authors.affiliation: Center for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. BOX 54840 - 00200, Mbagathi Rd., Nairobi, Kenya.
authors.forename: Philip
authors.initials: P
authors.lastname: Ngumbi
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods; D006224:Cricetinae; D031743:Cymbopogon / Q000737:chemistry*; D003671:DEET / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007300:Insect Control / Q000379:methods; D007302:Insect Repellents / Q000494:pharmacology*; D007303:Insect Vectors / Q000187:drug effects / Q000502:physiology; D009822:Oils, Volatile / Q000302:isolation & purification / Q000494:pharmacology*; D010691:Phlebotomus / Q000502:physiology*; D010938:Plant Oils / Q000302:isolation & purification / Q000494:pharmacology*; D013045:Species Specificity; D031686:Tagetes / Q000737:chemistry*
chemical_list: D007302:Insect Repellents; D009822:Oils, Volatile; D010938:Plant Oils; D003671:DEET
keywords: Cymbopogon citratus; Essential oil; Lemon grass; Mexican marigold; Phlebotomus duboscqi; Repellent; Tagetes minuta L.