Five aromatic plants against wild malaria vectors: an eco-friendly approach against Anopheles gambiae s.l. populations in Burkina Faso

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Résumé

Background Vector control strategies have predominantly relied on the use of synthetic chemicals, leading
to the widespread of resistance among malaria vector populations. This growing resistance has prompted increased
interest in alternative control methods, particularly those based on plant-derived essential oils (EOs). The present
study investigates the insecticidal efficacy of five essential oils against field populations of Anopheles gambiae sensu
lato from Burkina Faso. The objective was also to assess the current distribution and frequency of resistance-conferring mutations within these mosquito populations.
Methods Essential oils were extracted from Cymbopogon citratus, Cymbopogon nardus, Eucalyptus camaldulensis,
Lippia multiflora, and Ocimum americanum plants by hydrodistillation, and their chemical composition was analyzed
by gas chromatography coupled with mass spectrometry (GC–MS). The insecticidal activity of the EOs was evaluated
on Anopheles gambiae complex populations collected from fifteen localities, following the WHO tube bioassay protocol. Species identification in Anopheles complex was carried out by PCR. Molecular assays targeting specific resistance
genes, particularly the knockdown resistance (kdr) L1014F mutation, were conducted using allele-specific PCR. The KD
effect and mortality rates induced by each EO were recorded.
Results GC–MS analysis revealed among the 5 EOs samples tested, monoterpenes were the dominant compounds. The
KD effects of Cymbopogon citratus, Cymbopogon nardus and Lippia multiflora were more pronounced in all the study areas.
The comparative analysis of knockdown times at 50% and 95% (KDT50 and KDT95) highlights significant differences in efficacy between the tested essential oils and permethrin. Overall, the essential oils exhibited significantly lower KDT values
than permethrin, indicating a faster and potentially more effective action against Anopheles gambiae populations. Moreover,
L. multiflora induced a rate of mortality of 100% in mosquitoes from fifteen localities. Statistical analysis revealed significant
differences in mortality rates among the EOs tested. The potent insecticidal activity observed is likely due to the major terpenoid compounds present in these EOs. Among the mosquito populations analyzed, Anopheles arabiensis was predominant
and exhibited high phenotypic resistance to pyrethroids in multiple locations.
Conclusion The EOs of Cymbopogon citratus, Cymbopogon nardus, and Lippia multiflora could be used as alternatives
where pyrethroid resistance in malaria vectors has been established. These findings support the potential integration
of these plant-derived oils into environmentally sustainable vector management strategies in Burkina Faso.
Keywords Anopheles, Resistance, Essential oils, Insecticidal activity, Mortality

Mots-clés

Anopheles, Resistance, Essential oils, Insecticidal activity, Mortality