Electrophysiological and behavioral characterization of bioactive compounds of the Thymus vulgaris, Cymbopogon winterianus, Cuminum cyminum and Cinnamomum zeylanicum essential oils against Anopheles gambiae and prospects for their use as bednet treatments

Abstract

BackgroundLaboratory and field studies showed that repellent, irritant and toxic actions of common public health insecticides reduce human-vector contact and thereby interrupt disease transmission. One of the more effective strategies to reduce disease risk involves the use of long-lasting treated bednets. However, development of insecticide resistance in mosquito populations makes it imperative to find alternatives to these insecticides. Our previous study identified four essential oils as alternatives to pyrethroids: Thymus vulgaris, Cymbopogon winterianus, Cuminum cyminum, Cinnamomum zeylanicum. The objectives of this study were to identify active compounds of these essential oils, to characterize their biological activity, and to examine their potential as a treatment for bednets.MethodsWe evaluated the electrophysiological, behavioural (repellency, irritancy) and toxic effects of the major compounds of these oils against Anopheles gambiae strain ‘Kisumu’.ResultsAldehydes elicited the strongest responses and monoterpenes the weakest responses in electroantennogram (EAG) trials. However, EAG responses did not correlate consistently with results of behavioral assays. In behavioral and toxicity studies, several of the single compounds did exhibit repellency, irritancy or toxicity in An. gambiae; however, the activity of essential oils did not always correlate with activity expected from the major components. On the contrary, the biological activity of essential oils appeared complex, suggesting interactions between individual compounds and the insect under study. Data also indicated that the three effects appeared independent, suggesting that repellency mechanism(s) may differ from mechanisms of irritancy and toxicity.ConclusionsBased on the bioassays reported here, some of the compounds merit consideration as alternative bednet treatments.

The phytochemistry of Cymbopogon winterianus essential oil from Lombok Island, Indonesia and its antifungal activity against phytopathogenic fungi

“…C. jwarancusa was found to have a flukicidal activity which used as alternative sources of treatment for trematodes infection (Shafiq et al 2015). C. validus (Stapf) Stapf ex Burtt Davy had potential as an anti-inflammatory (Rungqu et al 2016), and C. winterianus was found exhibiting potential as a mosquito repellent, bioinsecticide (Deletre et al 2015;Sajo et al 2015;Silva et al 2018), and as an orofacial antinociceptive (Santos et al 2015).…”

Essential Oils as a Potential Treatment Option for Pediculosis

“…Therefore, a neutral solvent can be added to the experiments as a control. In addition, other constituents in minor quantities may also have a possible synergistic or antagonistic activity [41,107]. Among the 22 genera of essential oils discussed above, which were reported to have pediculicidal activities, certain genera such as Aloysia, Cinnamomum, Eucalyptus, Eugenia, Lavandula, Melaleuca, Mentha, Myrcianthes, Origanum, Pimpinella, and Thymus have demonstrated high efficacy in killing the lice, which makes them strong candidates for clinical assays [23,[115][116][117].…”

“…In addition, Cinnamomum species can repel or kill a variety of insects, includ-▶ Table 1 The major essential oils together with their characteristics reported to be effective against louse ectoparasites. ing Anopheles gambiae and Plodia interpunctella [29,41]. The main components of Cinnamomum species are cinnamaldehyde, benzaldehyde, and eugenol [39].…”

Essential Oils as an Alternative to Pyrethroids’ Resistance against Anopheles Species Complex Giles (Diptera: Culicidae)

“…The minor compounds could be also implicated in the adult mosquito toxicity of an essential oil. Thus, the toxicity of C. winterianus and C. cymimum oils could be due to their minor compounds, whereas this was not the case for C. zeylanicum and T. vulgaris oils, which toxicity could be due to cinnamaldehyde and the major compounds in the blend [ 90 ]. α-Pinene, limonene, terpinolene, citronellol, citronellal, camphor and thymol are common constituents of a number of essential oils that show mosquito repellent activity [ 91 , 92 , 93 , 94 , 95 ].…”