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Bioassays for Monitoring Insecticide Resistance
Published on: December 30, 2010
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Pyrethroid Resistance Situation across Different Eco-Epidemiological Settings in Cameroon
Nelly Armanda Kala-Chouakeu1,2, Paulette Ndjeunia-Mbiakop2,3, Idriss Nasser Ngangue-Siewe2,4
1Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon.
Molecules (Basel, Switzerland)
|October 14, 2022
Summary
Pyrethroid resistance in Anopheles gambiae mosquitoes is high across Cameroon, driven by kdr mutations and gene overexpression. This widespread resistance threatens malaria vector control efforts, necessitating urgent mitigation strategies.
Area of Science:
- Medical Entomology
- Molecular Biology
- Public Health
Background:
- Pyrethroid resistance in Anopheles gambiae is a major obstacle to malaria vector control in Cameroon.
- Limited data exists on the precise pyrethroid resistance status across diverse Cameroonian ecological settings.
Purpose of the Study:
- To assess the pyrethroid resistance profile of Anopheles gambiae populations in various eco-epidemiological settings in Cameroon.
- To identify the molecular mechanisms underlying pyrethroid resistance, including target-site mutations and gene expression.
Main Methods:
- Susceptibility bioassays were conducted on Anopheles gambiae females using permethrin and deltamethrin.
- Species identification within the Anopheles gambiae complex was performed using molecular diagnostics.
- Taqman assays were used to detect target-site resistance mutations (kdr alleles, N1575Y).
- Quantitative reverse transcription-real-time PCR (qRT-PCR) was employed to quantify detoxification gene expression.
- Cuticular hydrocarbon (CHC) content was analyzed.
Main Results:
- Anopheles gambiae, Anopheles coluzzii, and Anopheles arabiensis were identified, with varying dominance across sites.
- High frequencies of the kdr L1014F allele (43–100%) were observed in most locations.
- The kdr L1014S allele was found at low frequencies in Njombé and Tibati.
- The N1575Y mutation was detected in Kaélé, Santchou, Tibati, and Bertoua.
- Overexpression of six Cytochrome P450 genes was noted in several populations.
- Increased CHC content was observed in mosquito populations from Kaélé and Njombé.
Conclusions:
- Cameroon exhibits widespread pyrethroid resistance in Anopheles populations, with distinct resistance profiles across different ecological zones.
- The study highlights the significant role of kdr mutations and detoxification gene overexpression in pyrethroid resistance.
- Urgent interventions are required to mitigate the impact of insecticide resistance on malaria vector control programs.
