# Insecticide Resistance Management to Preserve Pyrethroid Susceptibility in Aedes aegypti

> **NIH NIH R01** · COLORADO STATE UNIVERSITY · 2020 · $331,899

## Abstract

Project Summary / Abstract
The mosquito Aedes aegypti is the primary urban vector of the viruses causing dengue and chikungunya fever
for which vaccines and effective pharmaceuticals are lacking. Epidemic dengue is emerging in the Americas:
Mexico has reported >750,000 clinical dengue cases since 2009. Endemic chikungunya fever was reported in
the Americas for the first time in 2013 and is now spreading into the Caribbean and Mexico. The only available
strategy to suppress dengue or chikungunya fever outbreaks is to reduce vector populations through
insecticide applications. However, Ae. aegypti suppression is compromised through a recent rapid rise across
Latin America of knockdown resistance (kdr) to pyrethroid insecticides. Widespread, heavy use of pyrethroid
space sprays – due to their strong human safety profile – has created immense selection pressure for
resistance. This resistance is primarily under the control of the voltage gated sodium channel gene (para). Our
preliminary data show that high frequencies (>80%) of kdr-conferring alleles occur commonly in Ae. aegypti in
Mexico, and that state-of-the-art netting treated with a synergized pyrethroid effectively kills susceptible Ae.
aegypti but has unacceptably low (~20%) killing efficacy for Mexican Ae. aegypti strains with high frequencies
of kdr-conferring alleles. Our preliminary studies also show that: a) even in the absence of gene flow barriers,
local insecticide pressure, rather than migration of mosquitoes with kdr-conferring mutations, is the primary
determinant of the local kdr profile for Ae. aegypti; and b) the frequency of kdr-conferring mutations in a highly
resistant strain reverted from near fixation to lower levels within 14 generations when pyrethroid pressure was
removed. These findings provide hope that the current, disastrous kdr situation can be reversed through
insecticide resistance management (IRM) schemes to restore and protect the invaluable pyrethroid
susceptibility resource in Ae. aegypti. The goals for this proposal are to demonstrate that pyrethroid
susceptibility can be restored and protected in Ae. aegypti and Ae. albopictus through insecticide rotation and
focused indoor spraying. We also will identify genes other than para that confer pyrethroid resistance in Ae.
aegypti through RNAseq and deep sequencing of exon enriched libraries. Our partnering Mexican institution is
Instituto Nacional de Salud Pública – Centro Regional de Investigación en Salud Pública (INSP-CRISP) in
Tapachula.

## Key facts

- **NIH application ID:** 9953968
- **Project number:** 5R01AI121211-05
- **Recipient organization:** COLORADO STATE UNIVERSITY
- **Principal Investigator:** Karla Lizet Saavedra Rodriguez
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $331,899
- **Award type:** 5
- **Project period:** 2016-07-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9953968

## Citation

> US National Institutes of Health, RePORTER application 9953968, Insecticide Resistance Management to Preserve Pyrethroid Susceptibility in Aedes aegypti (5R01AI121211-05). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9953968. Licensed CC0.

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