Wolbachia-Based Biocontrol of Aedes aegypti: Current Progress, Challenges, and Future Prospects.

Wolbachia is used as a potential biocontrol tool to reduce dengue mosquitoes and also to reduce dengue virus (DENV) load in transinfected Aedes aegypti. Different field trials including the ones by the World Mosquito Program (WMP) have deployed Wolbachia carrying DENV primary vectors at different target sites worldwide. Field trials suggest that through the Population Replacement Strategy (PRS) and Incompatible Insect Technique (IIT), Wolbachia can either introgress into the local Ae. aegypti population or reduce their population size by cytoplasmic incompatibility, leading to subsequent reduction in dengue incidence at target sites. Key challenges for this strategy include establishing and sustaining the transinfected mosquito population, selecting the appropriate bacterial strain, ensuring the long term establishment of transinfected dengue mosquitoes across multiple generations, determining appropriate approach for mosquito field release, addressing operational constraints, and managing potential viral evolution. Moreover, the outcome of Wolbachia mediated biological control of Ae. aegypti in a broad scale is yet to be seen and the long-term stability of Wolbachia in transinfected mosquitoes remains unconfirmed. Significant success has been recorded in a broad scale deployment of wAlbB-carrying Ae. aegypti through the ongoing Wolbachia Malaysia project, resulting in reduction of dengue fever cases. Successful large-deployment of this strategy has also been performed in Colombia and Indonesia (1.7 to 3.3 million people and 135-540 km2 area). Similar investigations on broad scale for longer period across different environmental conditions using transinfected mosquito deployment and associated risk analysis are imperative before adopting this biological control approach as a potent dengue control strategy worldwide.