Impact of insecticide resistance evolution on malaria vector control

Area of Science:

• Vector control
• Entomology
• Population genetics

Background:

• Insecticide-treated nets (ITNs) are crucial for malaria vector control.
• Insecticide resistance (IR) poses a significant threat to ITN efficacy.
• Understanding the interplay between ITNs, IR evolution, and malaria transmission is vital, especially with new NGM-ITNs.

Purpose of the Study:

• To model the simultaneous impact of ITNs on malaria transmission and IR evolution.
• To compare the effectiveness of pyrethroid-only ITNs (PYR-ITNs) and next-generation mixture ITNs (NGM-ITNs).
• To assess the role of insecticide resistance management (IRM) in evaluating ITN interventions.

Main Methods:

• Developed a mosquito population dynamics and genetics model.
• Simulated the long-term effects of ITN interventions, including net retention and insecticide decay.
• Conducted comparative analyses of PYR-ITNs and NGM-ITNs under various coverage scenarios.

Main Results:

• Higher ITN coverage consistently improved malaria vector control, irrespective of ITN type.
• NGM-ITNs demonstrated superior performance in both malaria transmission control and IRM compared to PYR-ITNs.
• NGM-ITNs provided greater benefits even at lower coverage rates than PYR-ITNs, due to reduced selection pressure and IRM effects. Insecticide selection on male mosquitoes emerged as a critical factor influencing malaria control loss.

Conclusions:

• Insecticide resistance management (IRM) is essential for accurately evaluating NGM-ITNs.
• Current evaluation pipelines may undervalue NGM-ITNs by not fully accounting for IRM.
• Incorporating IRM into evaluations ensures a comprehensive understanding of the long-term effectiveness of novel malaria control interventions.