Selection of mosquito life-histories: a hidden weapon against malaria?

Ferguson, H., Maire, N., Takken, W., Lyimo, I.N., Briet, O., Lindsay, S.W. and Smith, T. (2012) Selection of mosquito life-histories: a hidden weapon against malaria? Malaria Journal, 11, p. 106. (doi:10.1186/1475-2875-11-106)

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Abstract

Background There has recently been a substantial decline in malaria incidence in much of Africa. While the decline can clearly be linked to increasing coverage of mosquito vector control interventions and effective drug treatment in most settings, the ubiquity of reduction raises the possibility that additional ecological and associated evolutionary changes may be reinforcing the effectiveness of current vector control strategies in previously unanticipated ways. Presentation of hypothesis Here it is hypothesized that the increasing coverage of insecticide-treated bed nets and other vector control methods may be driving selection for a shift in mosquito life history that reduces their ability to transmit malaria parasites. Specifically it is hypothesized that by substantially increasing the extrinsic rate of mortality experienced in vector populations, these interventions are creating a fitness incentive for mosquitoes to re-allocate their resources towards greater short-term reproduction at the expense of longer-term survival. As malaria transmission is fundamentally dependent on mosquito survival, a life history shift in this direction would greatly benefit control. Testing the hypothesis At present, direct evaluation of this hypothesis within natural vector populations presents several logistical and methodological challenges. In the meantime, many insights can be gained from research previously conducted on wild Drosophila populations. Long-term selection experiments on these organisms suggest that increasing extrinsic mortality by a magnitude similar to that anticipated from the up-scaling of vector control measures generated an increase in their intrinsic mortality rate. Although this increase was small, an change of similar magnitude in Anopheles vector populations would be predicted to reduce malaria transmission by 80%. Implications of hypothesis The hypothesis presented here provides a reminder that evolutionary processes induced by interventions against disease vectors may not always act to neutralize intervention effectiveness. In the search for new intervention strategies, consideration should be given to both the potential disadvantages and advantages of evolutionary processes resulting from their implementation, and attempts made to exploit those with greatest potential to enhance control.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ferguson, Dr Heather
Authors: Ferguson, H., Maire, N., Takken, W., Lyimo, I.N., Briet, O., Lindsay, S.W., and Smith, T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Malaria Journal
ISSN:1475-2875
Copyright Holders:Copyright © 2012 The Authors
First Published:First published in Malaria Journal 11:106
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
425321A systems biology approach to infectious disease transmission - linking individuals, populations and ecosystemsHeather FergusonBiotechnology and Biological Sciences Research Council (BBSRC)BB/D020042/1RI BIODIVERSITY ANIMAL HEALTH & COMPMED