Insecticide resistance mechanisms in Anopheles gambiae complex populations from Burkina Faso, West Africa

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Résumé

ector control constitutes a fundamental approach in reducing vector density and the efficient option to break
malaria transmission in Africa. Malaria vectors developed resistance to almost all classes of insecticides recommended by WHO for vector control in most places of African countries and may compromise the vector control
strategies. This study updated the resistance status of Anopheles gambiae complex populations to insecticides recommended for vector control in the western part of Burkina Faso. Insecticide susceptibility bioassays were performed on seven natural populations of An. gambiae complex from western Burkina Faso in the 2016 rainy season
using the WHO protocol. Biochemical assays were carried out according to the WHO protocol on the same populations to estimate detoxifying enzymes activities including non-specific esterases (NSEs), oxidases (cytochrome
P450) and Glutathione-S-Transferases (GSTs). Polymerase Chain Reactions (PCRs) were performed for the identification of the An. gambiae complex species as well as the detection of kdr-west and ace-1 mutations. Susceptibility
bioassays showed that An. gambiae complex was multi-resistant to pyrethroids, DDT and carbamates in almost all
areas. The mortality rates ranged from 10 to 38%, 2.67 to 59.57% and 64.38 to 98.02% for Deltamethrin, DDT and
Bendiocarb respectively. A full susceptibility (100%) to an organophosphate, the Chlorpyrifos-methyl, was observed
at the different sites. Three (3) species of the An. gambiae complex were identified: An. gambiae s.s, An. coluzzii and
An. arabiensis. The frequencies of the kdr-w mutation were highly widespread (0.66 to 0.98) among the three species
of the complex. The ace-1 mutation was detected at low frequencies (0 to 0.12) in An. gambiae s.s and An. coluzzii. A
high level of GSTs and NSEs were observed within the different populations of the An. gambiae complex. Several
mechanisms of insecticide resistance were found simultaneously in the same populations of An. gambiae complex
conferring high multi-resistance to DDT, Carbamate and Pyrethroids. The full susceptibility of An. gambiae complex
to organophosphates is a useful data for the national malaria control program in selecting the most appropriate
products to both maintain the effectiveness of vector control strategies and best manage insecticide resistance as
well as developing new alternative strategies for the control of major malaria vectors in Burkina Faso.

Mots-clés

Malaria, Vector control, Pyrethroids resistance, Metabolic resistance