Delayed mortality effects cut the malaria transmission potential of insecticide resistant mosquitoes

Viana, M. , Hughes, A., Matthiopoulos, J. , Ranson, H. and Ferguson, H. M. (2016) Delayed mortality effects cut the malaria transmission potential of insecticide resistant mosquitoes. Proceedings of the National Academy of Sciences of the United States of America, 113(32), pp. 8975-8980. (doi:10.1073/pnas.1603431113) (PMID:27402740)

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Abstract

Malaria transmission has been substantially reduced across Africa through the distribution of long-lasting insecticidal nets (LLINs). However, the emergence of insecticide resistance within mosquito vectors risks jeopardizing the future efficacy of this control strategy. The severity of this threat is uncertain because the consequences of resistance for mosquito fitness are poorly understood: while resistant mosquitoes are no longer immediately killed upon contact with LLINs, their transmission potential may be curtailed because of longer-term fitness costs that persist beyond the first 24 h after exposure. Here, we used a Bayesian state-space model to quantify the immediate (within 24 h of exposure) and delayed (>24 h after exposure) impact of insecticides on daily survival and malaria transmission potential of moderately and highly resistant laboratory populations of the major African malaria vector Anopheles gambiae. Contact with LLINs reduced the immediate survival of moderately and highly resistant An. gambiae strains by 60–100% and 3–61%, respectively, and delayed mortality impacts occurring beyond the first 24 h after exposure further reduced their overall life spans by nearly one-half. In total, insecticide exposure was predicted to reduce the lifetime malaria transmission potential of insecticide-resistant vectors by two-thirds, with delayed effects accounting for at least one-half of this reduction. The existence of substantial, previously unreported, delayed mortality effects within highly resistant malaria vectors following exposure to insecticides does not diminish the threat of growing resistance, but posits an explanation for the apparent paradox of continued LLIN effectiveness in the presence of high insecticide resistance.

Item Type:Articles
Additional Information:Financial support was provided by European Commission Seventh Framework Programme Grant 265660 “AvecNet.”
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Viana, Dr Mafalda and Matthiopoulos, Professor Jason and Ferguson, Professor Heather
Authors: Viana, M., Hughes, A., Matthiopoulos, J., Ranson, H., and Ferguson, H. M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Proceedings of the National Academy of Sciences of the United States of America
Publisher:National Academy of Sciences
ISSN:0027-8424
ISSN (Online):1091-6490
Published Online:11 July 2016
Copyright Holders:Copyright © 2016 Viana et al.
First Published:First published in PNAS 113(32):8975-8980
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
539231AvecNet - African Vector Control: New toolsHeather FergusonEuropean Commission (EC)UNSPECIFIEDRI BIODIVERSITY ANIMAL HEALTH & COMPMED