Behavioral cost & overdominance in Anopheles gambiae

Area of Science:

• Entomology
• Molecular Biology
• Insecticide Resistance

Background:

• Widespread use of Insecticide Treated Nets (ITN) has led to insecticide resistance in Anopheles mosquitoes.
• The Kdr mutation confers physiological resistance to pyrethroid insecticides (PYR).

Purpose of the Study:

• To investigate the impact of the Kdr mutation on Anopheles gambiae's ability to locate and penetrate damaged nets.
• To assess the behavioral consequences and potential heterozygote advantage associated with the Kdr mutation.

Main Methods:

• Utilized a wind tunnel to test mosquito penetration of treated and untreated nets with a 1cm hole.
• Employed mosquito video-tracking to analyze host-seeking behavior.
• Compared penetration success rates across Kdr homozygous susceptible, heterozygous, and homozygous resistant Anopheles gambiae.

Main Results:

• Kdr homozygous resistant mosquitoes showed the lowest efficiency (51%) in penetrating untreated nets, suggesting a recessive behavioral cost.
• Kdr heterozygous mosquitoes exhibited the highest efficiency (overdominance) in penetrating PYR-treated nets, indicating heterozygote advantage.
• All mosquito groups demonstrated a strong ability to locate holes in bed nets.

Conclusions:

• The Kdr mutation imposes a behavioral cost on host-seeking in Anopheles mosquitoes, affecting penetration of untreated nets.
• Heterozygote advantage for the Kdr mutation exists in pyrethroid-treated nets, a significant finding for insecticide resistance management.
• Mosquitoes possess a remarkable capacity for hole detection in bed nets, irrespective of insecticide resistance status.