Spatial heterogeneity of insecticide resistance in the dengue vector Aedes aegypti in the Yucatan peninsula of Mexico presents unique vector control challenges Público
Deming, Regan Lee (2014)
Abstract
Background: The emergence of insecticide resistance in vector populations around the world threatens disease prevention and control. Dengue viruses, spread primarily by the Aedes aegypti mosquito, cause significant morbidity and mortality. Dengue is controlled mainly through insecticide application for vector control since there are no preventative medications or vaccines. Understanding how insecticide resistance moves through a population, its geographical distribution and the biological mechanisms underlying resistance is essential for effective evidence-based control programs.
Objective: This cross-sectional study is an initial assessment of insecticide resistance in Ae. aegypti mosquitoes across previously unstudied dengue-endemic towns in the Yucatan peninsula of Mexico. The study quantified the entomologic profile of these towns, phenotypic resistance and the frequency of two known molecular markers of resistance to certain pyrethroid insecticides.
Methods: Entomological surveys of Ae. aegypti were conducted in 5 towns in Yucatan, Mexico from June-August 2013. Emerged F0-F2 adults from eggs collected in each town were exposed to insecticides; deltamethrin, bendiocarb and chlorpyrifos and tested for resistance. Individuals tested against deltamethrin were also evaluated for the presence of two kdr mutations known to be associated with pyrethoid resistance, V1016I and F1534C, to assess the validity of these as molecular markers for deltamethrin resistance.
Results: CDC Bottle Bioassay tests showed high levels of resistance to deltamethrin and chrlorpyrifos, and limited resistance to bendiocarb, with variations between study towns. Frequencies ranged between 0.47-0.74 for the V1016I mutation and showed a highly significant association with deltamethrin resistance phenotype in each town (p <0.002). Frequencies ranging between 0.59-0.94 were found for the F1534C mutation, showing significant association with deltamethrin resistance phenotype in 3 of the 5 towns, (p =0.01, p <0.0001 and p<0.0001).
Discussion: These data have identified heterogeneity of insecticide resistance in previously unstudied populations and offer key insights into the development of these patterns. Several driving forces lead to development of insecticide resistance in mosquito populations, including pressure from insecticide application as well as human behavior and movement patterns. Heterogeneity of resistance patterns over a small geographical area poses a challenge to vector control programs, as employing interventions at a small scale is not always feasible.
Table of Contents
Abstract...iv
Acknowledgements...vi
Table of Contents...vii
Background...1
Methods...8
Results...16
Discussion...20
References...27
Tables...31
Figures...39
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