Targeting the Highly Invasive Malaria Vector Anopheles stephensi using Yeast RNAi Pesticides

Area of Science:

• Entomology
• Molecular Biology
• Pesticide Development

Background:

• Anopheles stephensi is a major invasive malaria vector threatening global control efforts.
• Insecticide and drug resistance in malaria parasites and vectors necessitate new control strategies.
• Yeast RNAi (RNA interference) pesticides offer a novel approach for vector control.

Purpose of the Study:

• To evaluate yeast-based RNAi pesticides for Anopheles stephensi control.
• To develop methods for delivering RNAi pesticides to adult and larval mosquitoes.
• To explore female-specific RNAi larvicides for male mosquito sorting.

Main Methods:

• Utilized a modified Saccharomyces cerevisiae yeast expressing RNAi targeting the Anopheles stephensi Shaker gene (Sh.463).
• Developed attractive targeted sugar bait (ATSB) systems for adult mosquito delivery and yeast-based systems for larval delivery.
• Screened female-specific genes using RNAi yeast larvicides to assess impact on mosquito populations.

Main Results:

• Sh.463 yeast treatment resulted in high mortality rates in Anopheles stephensi larvae and adults by silencing the Shaker gene.
• Female-specific RNAi larvicides significantly increased male:female ratios in offspring due to targeted female mortality.
• Demonstrated successful gene silencing and mortality in laboratory assays.

Conclusions:

• RNAi pesticides targeting mosquito Shaker genes represent a potential biorational intervention for integrated Anopheles stephensi control.
• Yeast RNAi technology can be adapted for targeting other disease vector mosquitoes.
• Female-specific RNAi yeast larvicides show potential for sex-sorting in mosquito populations.