Multiple insecticide resistance and Plasmodium infection in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the Yaoundé airport, Cameroon

Nkemngo, F. N. et al. (2020) Multiple insecticide resistance and Plasmodium infection in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the Yaoundé airport, Cameroon. Wellcome Open Research, 5, 146. (doi: 10.12688/wellcomeopenres.15818.2) (PMID:33204845) (PMCID:PMC7667521)

Abstract

Background: Reducing the burden of malaria requires better understanding of vector populations, particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the Yaoundé international airport, Cameroon, including species composition, abundance, Plasmodium infection rate, insecticide resistance profiles and underlying resistance mechanisms. Methods: Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a locality situated 2 km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F 1 adults. Bioassays were performed to assess resistance profile to the four insecticides classes. The threshold of insecticide susceptibility was defined above 98% mortality rate and mortality rates below 90% were indicative of confirmed insecticide resistance. Furthermore, the molecular basis of resistance and Plasmodium infection rates were investigated. Results: Anopheles funestus s.s. was the most abundant species in Elende (85%) followed by Anopheles gambiae s.s. (15%) with both having similar sporozoite rate. Both species exhibited high levels of resistance to the pyrethroids, permethrin and deltamethrin (<40% mortality). An. gambiae s.s. was resistant to DDT (9.9% mortality) and bendiocarb (54% mortality) while susceptible to organophosphate. An. funestus s.s. was resistant to dieldrin (1% mortality), DDT (86% mortality) but susceptible to carbamates and organophosphates. The L119F-GSTe2 resistance allele (8%) and G119S ace-1 resistance allele (15%) were detected in An. funestus s.s. and An. gambiae s.s., respectively. Furthermore, the high pyrethroid/DDT resistances in An. gambiae corresponded with an increase frequency of 1014F kdr allele (95%). Transcriptional profiling of candidate cytochrome P450 genes reveals the over-expression of CYP6P5, CYP6P9a and CYP6P9b. Conclusion: The resistance to multiple insecticide classes observed in these vector populations alongside the significant Plasmodium sporozoite rate highlights the challenges that vector control programs encounter in sustaining the regular benefits of contemporary insecticide-based control interventions in forested areas.

• Item Type: Articles
• Additional Information: Version 2; peer review: 2 approved. This work was funded by a Wellcome Trust Senior Research Fellowship in Biomedical Sciences to CSW (101893) and a DFG grant (BO 2494/3-1) to SB and CSW.
• Keywords: Anopheles funestus, Anopheles gambiae, Cameroon, insecticide resistance, malaria, Plasmodium infection, vctor control.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Niang, Dr Abdoulaye

Creator Roles

Niang, A.: Investigation, Writing – review and editing

• Authors: Nkemngo, F. N., Mugenzi, L. M.J., Terence, E., Niang, A., Wondji, M. J., Tchoupo, M., Nguete, N. D., Tchapga, W., Irving, H., Ntabi, J. D.M., Agonhossou, R., Boussougou-Sambe, T. S., Akoton, R. B., Koukouikila-Koussounda, F., Pinilla, Y. T., Ntoumi, F., Djogbenou, L. S., Ghogomu, S. M., Ndo, C., Adegnika, A. A., Borrmann, S., and Wondji, C. S.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Wellcome Open Research
• Publisher: F1000Research
• ISSN: 2398-502X
• ISSN (Online): 2398-502X
• Copyright Holders: Copyright © 2020 Nkemngo FN et al.
• First Published: First published in Wellcome Open Research 5: 146
• Publisher Policy: Reproduced under a Creative Commons License
• Data DOI: 10.17605/OSF.IO/XN68J