DEPARTMENT OF DEFENSE - CONGRESSIONALLY DIRECTED MEDICAL RESEARCH PROGRAMS

Novel RNAi Ovitraps to Protect Service Members from Mosquito-Borne Illnesses

Posted October 13, 2021

Molly Duman Scheel, Ph.D., Indiana University
David Severson, Ph.D., University of Notre Dame

Molly Duman Scheel, Ph.D., Indiana University
Dr. Molly Duman Scheel
David Severson, Ph.D., University of Notre Dame
Dr. David Severson

Illnesses transmitted by mosquitoes are a significant public health concern and are of particular importance for the military. There are currently no approved vaccines against many of the diseases spread by mosquitoes, such as Chikungunya, Dengue fever, malaria, West Nile virus, and Zika virus, so mosquito control measures remain critical for protection. Service Members are at higher risk of mosquito exposure during deployment, especially to locations where mosquito-transmitted illnesses are common. Additionally, many commonly used pesticides can cause health and safety issues in both humans and to the local environment, and resistance to these pesticides often emerges in mosquito populations. Therefore, creative, effective, and safe mosquito control measures are needed to prevent the spread of dangerous mosquito-borne illnesses within both the military and the general public.

Aedes SugarBait
Aedes mosquito drinks sugar bait containing RNAi insecticides.

Drs. Molly Duman Scheel and David Severson were awarded a Fiscal Year 2016 (FY16) Peer Reviewed Medical Research Program (PRMRP) Investigator-Initiated Research Award with Partnering PI Option to develop and test ovitraps (i.e., containers to lure and kill female mosquitoes that are carrying eggs). These ovitraps utilize RNA interference (RNAi) technology to create pesticides that kill mosquito larvae. RNAi is the introduction of double-stranded RNA into an organism to turn off or “silence” specific, targeted genes.1 The research team identified interfering RNAs that could silence genes required for mosquito survival, creating novel interfering RNA pesticides (IRPs) that could kill mosquito larvae when ingested. This technology has been shown to be highly effective in mosquito control by Drs. Duman Scheel and Severson’s team and is a new type of pesticide, designed to kill only the target organism, with minimal to no effect on the environment or other insects and humans. Advances in oral RNAi for mosquito control by Dr. Duman Scheel are detailed in a 2020 publication in Current Opinion in Insect Science.

Inspects water storage container for mosquito larvae

Dr. David Severson inspects a water storage container for mosquito larvae. Aedes larvae are often found in water storage containers located next to homes.
Tests RNAi-based yeast larvicides
Dr. Molly Duman Scheel tests RNAi-based yeast larvicides at the University of the West Indies, St. Augustine, Trinidad and Tobago field site.

The FY16 PRMRP award funded research that showed the validity, scalability, and low overall cost of the IRP system. Dr. Duman Scheel and her team selected Saccharomyces cerevisiae (Baker's yeast) as the delivery system for the IRPs because it can be produced inexpensively in large quantities. Analysis of the yeast delivery system is detailed in a publication in Current Drug Targets in 2019. The research team also showed that the system attracted mosquitoes to lay their eggs in the ovitraps containing the yeast interfering RNA technology. Mosquito larvae were killed after hatching and eating the yeast IRPs. This system was tested in the Caribbean, where both the effectiveness of larvae control and general public perception were evaluated. Consumers in the local area provided valuable feedback for implementation and acceptance of this new mosquito control system. One of the most significant concerns was that consumers wanted pesticide systems that last for a long time after initial application and are inexpensive to maintain. They also hoped for an expanded system that could also kill adult mosquitoes.

In FY20, Dr. Duman Scheel was awarded a PRMRP Expansion Award to expand the yeast interfering RNA technology to kill adult mosquitoes. The goals of the FY20 award include testing the effectiveness of the system for adult mosquito control, evaluating the technology in Southeast Asia and the Caribbean, and assessing consumer acceptance in those areas. Manufacturing will also be a focus of this award, specifically to develop large quantities of commercial-grade, shelf-stable pesticide formulas that could be easily deployed to Service Members throughout the world. Dr. Duman Scheel was also awarded an additional grant from the Department of Defense under the Deployed War Fighter Protection Program, focusing on pesticide discovery for targeting adult mosquito populations.2 The research led by Drs. Duman Scheel and Severson has generated an effective and consumer-accepted ovitrap system to kill mosquito larvae, and they are continuing their groundbreaking work in mosquito control around the world, which could ultimately be used to protect our Service Members from dangerous mosquito-transmitted diseases.

Community engagement events in Trinidad
Dr. Duman Scheel and Dr. Severson (at right), together with their research team, conducted community engagement events in Trinidad.
These forums engaged Trinidad stakeholders regarding their perceptions of the yeast RNAi-based ovitraps being evaluated by the research team. Also shown (starting at far left): research team members Brent Daniel, Akilah Stewart, Limb Hapairai, and Nikhella Winter.

References:

1How RNAi works. UMass Medical School RNA Therapeutics Institute. https://www.umassmed.edu/es/rti/biology/rna/how-rnai-works/

2IU researcher awarded two grants for work in abating mosquito-borne illnesses. Homeland Preparedness News. https://homelandprepnews.com/stories/23311-iu-researcher-awarded-two-grants-work-abetting-mosquito-borne-illnesses/

Publications:

Wiltshire R, and Duman-Scheel M. 2020. Advances in oral RNAi for disease vector mosquito research and control. Current Opinion in Insect Science 40:18-23. doi:10.1016/j.cois.2020.05.002.

Duman-Scheel M. 2019. Saccharomyces cerevisiae (baker's yeast) as an interfering RNA expression and delivery system. Current Drug Targets 20(9):942-952. doi:10.2174/1389450120666181126123538.

Links:

Abstracts for Dr. Duman Scheel
Public and Technical Abstracts: Effective Interfering RNA Lure-and-Kill-Baited Ovitraps for Biorational Aedes Zika Vector Mosquito Control

Abstracts for Dr. Severson
Public and Technical Abstracts: Effective Interfering RNA Lure-and-Kill-Baited Ovitraps for Biorational Aedes Zika Vector Mosquito Control

Top of Page

Last updated Wednesday, October 13, 2021