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Topical Application Bioassay to Quantify Insecticide Toxicity for Mosquitoes and Fruit Flies
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Mosquitoes cloak their legs to resist insecticides
Vasileia Balabanidou1, Mary Kefi1,2, Michalis Aivaliotis1,3,4
1Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece.
Proceedings. Biological Sciences
|July 18, 2019
Summary
Insecticide resistance in malaria mosquitoes is increasing due to thicker leg cuticles. This structural change in Anopheles gambiae reduces insecticide uptake, contributing to rising malaria incidence.
Area of Science:
- Entomology
- Molecular Biology
- Public Health
Background:
- Insecticides have halved malaria incidence since 2000, but widespread resistance threatens progress.
- Resistance mechanisms in Anopheles gambiae, like detoxification enzymes and target site mutations, are known, but new phenotypes suggest additional factors.
- The increasing incidence of malaria in 2018 may be linked to escalating insecticide resistance.
Purpose of the Study:
- To investigate novel resistance mechanisms in Anopheles gambiae beyond known genetic factors.
- To analyze structural and chemical changes in mosquito legs, a key site for insecticide absorption.
- To determine how these alterations contribute to the overall insecticide resistance phenotype.
Main Methods:
- Comparative analysis of leg cuticle structure and composition between insecticide-resistant and susceptible Anopheles gambiae.
- Microscopic examination of leg tissues to assess cuticle thickness and composition.
- Analysis of cuticular hydrocarbons in resistant and susceptible female mosquitoes.
Main Results:
- Resistant Anopheles gambiae exhibit a leg-thickening phenotype due to enhanced deposition of cuticular proteins and chitin.
- Resistant female mosquitoes possess significantly higher amounts and altered profiles of cuticular hydrocarbons on their legs.
- These structural and chemical modifications in the legs lead to reduced insecticide uptake.
Conclusions:
- Mosquito leg cuticle remodeling is a significant, previously underestimated mechanism contributing to insecticide resistance.
- Altered leg cuticle structure and composition in Anopheles gambiae directly impede insecticide penetration.
- Understanding these novel resistance mechanisms is crucial for developing effective malaria control strategies.
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