Two years evolution of deltamethrin, malathion and pirimiphosmethyl resistance in Aedes aegypti from urban in peri urban sites of Ouagadougou, Burkina Faso

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Résumé

Arboviral diseases such as dengue, chikungunya, and yellow fever are major public health concerns in Africa, with
Aedes aegypti as the primary vector. Insecticide-based interventions remain the cornerstone of vector control,
but their effectiveness is increasingly compromised by the evolution of resistance. Monitoring resistance
dynamics is therefore essential to guide sustainable control strategies. Adults emerged from eggs collected in
urban and peri-urban sites of Ouagadougou in 2019 and 2020, were exposed to insecticide-treated papers
according to WHO standard tubes protocols. Mosquitoes were exposed to 0.03% deltamethrin, 0.08% malathion,
and 0.21% pirimiphos-methyl for one hour. The mortality rate was recorded 24 hours after exposure and
compared across years and sites using Chi-square test. The tested populations were resistant to deltamethrin,
with lower mortality rates at the urban site (20.20% in 2019 vs. 23.76% in 2020; p = 0.5434) but a significant
change at the peri-urban site (70.24% vs. 24.30%; p < 0.001). The resistance to malathion was moderate with,
mortality rate decreasing from 91.51% to 82.98% in the urban site (p = 0.069), and from 98.99% to 59.61% in the
peri-urban site (p= 0.001). Pirimiphos-methyl mortality rates slightly drop from 80.39% to 74.72% (p=0.44) in
urban site and from 93.20% to 84.69% (p=0.001). These findings reveal a worrying trend of reducing
susceptibility of Aedes aegypti to both pyrethroids and organophosphates, particularly in peri-urban areas within
in one year. The results underscore the urgent need for continuous resistance monitoring and the implementation
of early resistance management strategy to sustain arbovirus prevention efforts in Burkina Faso.

Mots-clés

Aedes aegypti, Dengue, Insecticides resistance evolution, Ouagadougou