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Author Notes:

Regan Deming, Email:rldeming@gmail.com

AL, GVP and PMS conceived of and designed the study; RD, AMB, EUKC, ACM and BJ carried out the fieldwork; RD, KL and LV carried out the labwork; RD analyzed the data; RD, AL and GVP drafted the manuscript.

All authors provided critical input regarding the findings and all authors read and approved the final manuscript. Go to:

We are grateful to the people of San Lorenzo, Progreso, Acanceh, Hunucma, and Conkal for allowing us to sample mosquitoes in their homes.

The findings and conclusions in this paper are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

The authors declare that they have no competing interests.

Subjects:

Research Funding:

This work was partially funded from Emory University's Open Access Publishing Fund

Funding for this study was provided to PMS by the Consejo Nacional de Ciencia y Tecnología (CONACYT Mexico), Fondo Sectorial de Investigación en Salud y Seguridad Social (SSA/IMSS/ISSSTE-CONACYT) (SALUD-2011-1-161551).

Keywords:

  • Aedes aegypti
  • Dengue
  • Insecticide resistance
  • kdr

Spatial variation of insecticide resistance in the dengue vector Aedes aegypti presents unique vector control challenges

Tools:

Journal Title:

Parasites and Vectors

Volume:

Volume 9, Number 1

Publisher:

Type of Work:

Article | Final Publisher PDF

Abstract:

Background: Dengue is a major public health problem in Mexico, where the use of chemical insecticides to control the principal dengue vector, Aedes aegypti, is widespread. Resistance to insecticides has been reported in multiple sites, and the frequency of kdr mutations associated with pyrethroid resistance has increased rapidly in recent years. In the present study, we characterized patterns of insecticide resistance in Ae. aegypti populations in five small towns surrounding the city of Merida, Mexico. Methods: A cross-sectional, entomological survey was performed between June and August 2013 in 250 houses in each of the five towns. Indoor resting adult mosquitoes were collected in all houses and four ovitraps were placed in each study block. CDC bottle bioassays were conducted using F0-F2 individuals reared from the ovitraps and kdr allele (Ile1016 and Cys1534) frequencies were determined. Results: High, but varying, levels of resistance to chorpyrifos-ethyl was detected in all study towns, complete susceptibility to bendiocarb in all except one town, and variations in resistance to deltamethrin between towns, ranging from 63-88 % mortality. Significant associations were detected between deltamethrin resistance and the presence of both kdr alleles. Phenotypic resistance was highly predictive of the presence of both alleles, however, not all mosquitoes containing a mutant allele were phenotypically resistant. An analysis of genotypic differentiation (exact G test) between the five towns based on the adult female Ae. aegypti collected from inside houses showed highly significant differences (p < 0.0001) between genotypes for both loci. When this was further analyzed to look for fine scale differences at the block level within towns, genotypic differentiation was significant for both loci in San Lorenzo (Ile1016, p = 0.018 and Cys1534, p = 0.007) and for Ile1016 in Acanceh (p = 0.013) and Conkal (p = 0.031). Conclusions: The results from this study suggest that 3 years after switching chemical groups, deltamethrin resistance and a high frequency of kdr alleles persisted in Ae. aegypti populations. The spatial variation that was detected in both resistance phenotypes and genotypes has practical implications, both for vector control operations as well as insecticide resistance management strategies.

Copyright information:

© 2016 Deming et al.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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