Chemical composition and insecticidal activity of plant essential oils from Benin against Anopheles gambiae (Giles)

Abstract

BackgroundInsecticide resistance in sub-Saharan Africa and especially in Benin is a major public health issue hindering the control of the malaria vectors. Each Anopheles species has developed a resistance to one or several classes of the insecticides currently in use in the field. Therefore, it is urgent to find alternative compounds to conquer the vector. In this study, the efficacies of essential oils of nine plant species, which are traditionally used to avoid mosquito bites in Benin, were investigated.MethodsEssential oils of nine plant species were extracted by hydrodistillation, and their chemical compositions were identified by GC-MS. These oils were tested on susceptible “kisumu” and resistant “ladji-Cotonou” strains of Anopheles gambiae, following WHO test procedures for insecticide resistance monitoring in malaria vector mosquitoes.ResultsDifferent chemical compositions were obtained from the essential oils of the plant species. The major constituents identified were as follows: neral and geranial for Cymbopogon citratus, Z-carveol, E-p-mentha-1(7),8-dien-2-ol and E-p-mentha-2,8-dienol for Cymbopogon giganteus, piperitone for Cymbopogon schoenanthus, citronellal and citronellol for Eucalyptus citriodora, p-cymene, caryophyllene oxide and spathulenol for Eucalyptus tereticornis, 3-tetradecanone for Cochlospermum tinctorium and Cochlospermum planchonii, methyl salicylate for Securidaca longepedunculata and ascaridole for Chenopodium ambrosioides. The diagnostic dose was 0.77% for C. citratus, 2.80% for E. tereticornis, 3.37% for E. citriodora, 4.26% for C. ambrosioides, 5.48% for C. schoenanthus and 7.36% for C. giganteus. The highest diagnostic doses were obtained with S. longepedunculata (9.84%), C. tinctorium (11.56%) and C. planchonii (15.22%), compared to permethrin 0.75%. A. gambiae cotonou, which is resistant to pyrethroids, showed significant tolerance to essential oils from C. tinctorium and S. longepedunculata as expected but was highly susceptible to all the other essential oils at the diagnostic dose.ConclusionsC. citratus, E. tereticornis, E. citriodora, C. ambrosioides and C. schoenanthus are potential promising plant sources for alternative compounds to pyrethroids, for the control of the Anopheles malaria vector in Benin. The efficacy of their essential oils is possibly based on their chemical compositions in which major and/or minor compounds have reported insecticidal activities on various pests and disease vectors such as Anopheles.

Chemical&nbsp;Variability and&nbsp;Biological Activities of&nbsp;<em>Eucalyptus</em> spp. Essential Oils

“…In general, it affords good extraction yields of EOs as observed in the studies from plants cultivated in India [54] and in Benin [99] (4.8% and 4.6% yields, respectively). Lower oil yielding species were found, however, in India (0.6%) [26], in São Paulo State, Brazil (0.66%) [70,71] and Colombia (0.70%) [102].…”

“…The observed insecticide activity of E. tereticornis EOs on A. gambiae was associated to p-cymene and 1,8-cineole as demonstrated by the biological assays conducted with these individual components [99].…”

“…Two studies conducted in Benin found EOs presenting p-cymene as the main component. In one of these investigations, the plant species had 16.7% of p-cymene besides caryophyllene oxide (14.2%), spathulenol (13.5%) and cryptone (11.4%) [99]. In another study, the oils were found to have 31.1% of p-cymene and 9.7% of β-phellandrene [133].…”

The Artemisia Genus: A Review on Traditional Uses, Phytochemical Constituents, Pharmacological Properties and Germplasm Conservation

“…Both of these compounds hold anti feedent and anti-oxidant properties [105]. An alcoholic extract of A. asiatica possesses two compounds, selin-11-en-ol and 1,8-cineole which harbour significant anti-bacterial and anti-fungal properties [70].…”

A phytochemical of modern medicinal perspective

“…Hydrodistillation process was used for the separation of volatile oils of Cymbopogon citrates, Cymbopogon schoenanthus, Securidaca longepedunculata, C. ambrosioides, Cochlospermum tinctorium, Cochlospermum planchonii and Cymbopogon giganteus, and further their chemical characteristics were checked by GC-MS technique. Ascaridole was found to be the major active constituent in C. ambrosioides [34]. Hydrodistillation method was used for the separation of essential oil from the leaves of Curcuma longa L. and further it was subjected to GC-MS technique to know their chemical constituents.…”