Inside every mosquito is a hidden ecosystem of viruses and this may help determine which diseases they spread, according to new research published in Nature Communications.
Mosquitoes are best known for transmitting viruses like dengue, malaria and yellow fever. In a global study of the yellow fever mosquito, Aedes aegypti, scientists uncovered dozens of viruses actively infecting mosquitoes across the Americas, Africa and Asia. Together, these viruses form a kind of internal ecosystem where they coexist and interact. In some cases, the viruses are competing, according to study coauthor Matthew DeGennaro, a neurogeneticist in FIU's Department of Biological Sciences and director of the Biomolecular Sciences Institute. This hidden world of viruses can trigger a process known as RNA interference where the mosquito's natural immunity kicks in to reduce virus replication.
"I was happy to contribute mosquito samples from our field collections," DeGennaro said. "Miami is a gateway for vector-borne disease, and understanding how Aedes aegypti mosquitoes manage viral infections is crucial."
Some viruses appear to persist quietly across generations, passed from one mosquito to the next. Others vary by region, creating distinct viral signatures in mosquito populations around the world. These differences could help explain why outbreaks are difficult to predict and why the same disease does not spread the same way everywhere.
"We have been working to understand mosquito infestation seasonal dynamics and disease risk in Miami-Dade County, and it is exciting that our samples also contributed to the discovery of viruses that persist within mosquito populations," said Andre Costa-da-Silva, FIU research assistant professor and co-author of the study.
The findings are changing how scientists understand mosquito-borne disease. Rather than viewing mosquitoes as simple carriers, the study suggests their internal viral ecosystems play an active role in shaping disease dynamics. That insight could open the door to new strategies for controlling outbreaks not just by targeting mosquitoes themselves, but by better understanding the RNA landscape inside them. As warmer temperatures expand mosquito habitats into new regions, this knowledge is increasingly important.
To prevent the next outbreak, it may be more important to track the mosquito's own immune responses rather than the immune responses of people.
