Repellency of essential oils of some plants from the Kenyan coast against Anopheles gambiae

Abstract

Volatile oils extracted by hydrodistillation from six plant species growing in the Kenyan coast, Croton pseudopulchellus Pax, Mkilua fragrans Verdc. (Annonaceae), Endostemon tereticaulis (poir.) Ashby, Ocimum forskolei Benth., Ocimum fischeri Guerke and Plectranthus longipes Baker (Labiateae), were evaluated for repellency on forearms of human volunteers against Anopheles gambiae sensu stricto. All oils were found to be more repellent (RC50 range = 0.67-9.21 x 10(-5) mg cm(-2)) than DEET (RC50 = 33 x 10(-5) mg cm(-2)). The individual components of the oils were identified by GC-MS and GC co-injections with authentic standards.The repellency of 15 of the main constituents of the different oils (which had not been previously assayed) was evaluated. Although some of these showed relatively high individual repellencies, none was comparable to the parent essential oils. Partial synthetic blends of selected constituents with moderate or relatively high individual repellency against the vector were also assayed. Four of these exhibited activities comparable to or higher than those of the corresponding parent oils, indicating interesting blend effects in the repellent action of the oils against the mosquito. The implication of these results in the utilization of the plants is discussed.

Toxicity effect of Delonix elata (Yellow Gulmohr) and predatory efficiency of Copepod, Mesocyclops aspericornis for the control of dengue vector, Aedes aegypti

“…The percentage of mortality was 100% in first and second instars whereas 96%, 92% in third and fourth instars. Fitted probit-mortality curves for larvae indicated the median and 90% lethal concentrations of D. elata for instars [1][2][3][4] to be 4.91 (8.13), 5.16 (8.44), 5.95 (7.76) and 6.87 (11.23), respectively. The results indicate that leaf extract exhibits significant biological activity against life stages.…”

“…Mosquitoes are a serious threat to public health transmitting several dangerous diseases for over 2 billion people in the tropics [2] . Ae.…”

Evaluation of Ocimum suave essential oil against anthropophilic malaria vector Anopheles gambiae s.s after ten years of storage

“…In addition, the compounds might undergo chemical reaction with ingredients of some of the solvents used to make oil for skin application. The use of proper solvents, storage in dark and cool places might increase their longevity and thus provide an appropriate alternative tool to supplement the existing control methods against haematophagus insects (Omolo et al, 2004;Odalo et al, 2005).…”

Repellent and Insecticide Activity of Pelargonium x hortorum against Spodoptera littoralis (Boisd.)

“…Phthalic acid esters and di-n-butyl phthalate are used as insect repellents (Farm Chemicals, 1971). Odalo et al (2005) stated that one of the most potent repellents against Anopheles gambiae was phytol.…”