This project will advance ribonucleic acid interference (RNAi) as a control measure for invasive ants, delivering a final product for at least one invasive ant species to strengthen biosecurity options across Department of War (DoW) Indo-Pacific installations. Invasive ants damage ecosystems, economies, and military operations—particularly on islands and coastal regions where infestations serve as sources for introductions to new locations. By developing effective RNAi-based controls, this work addresses a critical vulnerability in regional operations.

RNAi is a well-established method in molecular biology for silencing specific genes in living organisms by introducing double-stranded RNA (dsRNA) that is complementary to a targeted gene. In the laboratory, this is often done by micro-injecting dsRNA constructs into the target organisms. However, the project team has developed a novel approach of feeding invasive ants dsRNAs that target genes that are essential for survival, potentially causing widespread mortality and allowing the control or eradication of entire invasive ant populations. Because these dsRNAs are designed to target gene sequences that are unique to the invasive species, non-target organisms should be unaffected.

The approach incorporates several advances that were developed under previous SERDP research, including identification of several gene targets, improved dsRNA construct design, discovery of an additive that significantly increases efficacy, and identification of effective dose concentrations. The primary remaining hurdle is scaling up this approach in a cost-effective way. This challenge is addressed by testing methods for increasing efficacy and dsRNA production. Specifically, the project team will continue to do research that builds on these advances by: 

• Identifying new gene targets and quantifying mortality when they are silenced. 
• Determining the efficacy of various construct designs. 
• Testing the possibility of silencing multiple genes simultaneously. 
• Testing and optimizing hydrogels as a delivery matrix for dsRNA in the field.  
• Testing bacterial expression systems for large-scale production of dsRNA. 

In addition, two contingency objectives are suggested, in the event of suboptimal results in the first four objectives, to:  

• Determine if there is expression of compensatory genes that masks silencing of target genes. 

• Test alternative delivery matrices, if hydrogels prove ineffective. 

Invasive ants pose an urgent threat to Indo-Pacific installations, damaging ecosystems, infrastructure, and operational readiness while serving as sources for introductions to new locations. This research will deliver a species-specific RNAi-based control technology that addresses this biosecurity challenge without harming non-target organisms, which is a critical advantage in sensitive ecosystems where DoW installations operate.

The approach targets genes essential to invasive ant survival, allowing for control or eradication of entire populations through a novel feeding mechanism rather than traditional labor-intensive methods. By building on advances from previous SERDP research, including identified gene targets, improved construct design, and optimized dose concentrations, this project focuses on the remaining hurdle: scaling production and delivery cost-effectively. Testing hydrogel delivery matrices and bacterial expression systems for large-scale dsRNA production will enable installation managers to deploy this technology operationally. (Anticipated Project Completion - 2028)