Alternatives to Pyrethroid Resistance: Combinations of Cymbopogon nardus and Ocimum americanum Essential Oils Improve the Bioefficiency Control Against the Adults’ Populations of Aedes aegypti (Diptera: Culicidae)

Abstract

Dengue vector control strategies are mostly based on chemicals use against Aedes aegypti populations. The current study aimed at investigating the insecticidal effects of essential oils (EOs) obtained from five plant species, Cymbopogon citrates (D. C.) Stapf. (Poaceae), Cymbopogon nardus (Linn.) Rendle (Poaceae), Eucalyptus camaldulensis Linn. (Myrtaceae), Lippia multiflora Moldenke (Verbenaceae), and Ocimum americanum Linn. Lamiaceae, and combinations of Cymbopogon nardus and Ocimum americanum on Ae. aegypti populations from Bobo-Dioulasso. For this purpose, adults of the susceptible and field strains of Ae. aegypti were tested in WHO tubes with EO alone and binary combinations of O. americanum (OA) and C. nardus (CN; scored from C1 to C9). The extraction of the essential oils was done by hydrodistillation, and their components were determined by GC/MS. Among the 5 EOs tested, L. multiflora essential oil was the most efficient, with KDT50 values below 60 min on all Ae. aegypti strains tested, and also with a rate of mortality up to 100 and 85% for Bora Bora and Bobo-Dioulasso strains, respectively. This efficacy may be due to its major compounds which are with major compounds as β-caryophyllene, p-cymene, thymol acetate, and 1.8 cineol. Interestingly, on all strains, C8 combination showed a synergistic effect, while C2 showed an additive effect. These combinations exhibit a rate of mortality varying from 80 to 100%. Their toxicity would be due to the major compounds and the putative combined effects of some major and minor compounds. More importanly, L. multiflora EO and combinations of C. nardus and O. americanum EO, may be used as alternatives against pyrethroid resistant of Ae. aegypti.

The excito-repellent activity of five essential oils extracted from local plants against dengue and malaria vectors in Burkina Faso

“…gambiae (Balboné et al 2022b(Balboné et al , 2022c. In addition to their toxic effect shown recently by Balboné et al (2022bBalboné et al ( , 2022c, L. multi ora exerted an irritant effect on Anopheles and Aedes populations. That is useful in terms of its use in vector control strategies.…”

“…aegypti and An. gambiae, respectively (Balboné et al 2022b(Balboné et al , 2022c. On the other hand, studies conducted in Guinea Bissau, West Africa, had reported that O. americanum EO had also a repellent effect on Anopheles mosquitoes (Pålsson & Jaenson, 1999).…”

“…aegypti and An. gambiae (Balboné et al 2022a(Balboné et al , 2022b. This EO tested recently for its toxicity gave a mortality rate of 0 to 8% (Balboné et al 2022a(Balboné et al , 2022b.…”

“…gambiae (Balboné et al 2022a(Balboné et al , 2022b. This EO tested recently for its toxicity gave a mortality rate of 0 to 8% (Balboné et al 2022a(Balboné et al , 2022b. Overall, O. americanum another EO which is less toxic (Balboné et al 2022a(Balboné et al , 2022b) displayed a signi cant contact irritant effect on susceptible strains of Ae.…”