Israeli scientists from Hebrew University unveiled a new gene-editing method today, December 17, to easily identify disease-carrying mosquitoes, revolutionizing.

Mosquitoes are among the most dangerous animals to humans, primarily due to their role in spreading disease. Female mosquitoes transmit viruses and parasites when they bite, including Dengue, Zika, Chikungunya, malaria, yellow fever, and West Nile virus. Together, these diseases infect hundreds of millions of people each year.

Only female mosquitoes transmit diseases to humans. Female mosquitoes bite because they need blood proteins to develop their eggs. When they feed, they can pick up viruses or parasites from an infected person or animal and later pass them on to another host through subsequent bites. Male mosquitoes feed on nectar and plant sugars and do not bite.

Currently, mosquito control programs such as the Sterile Insect Technique aim to suppress populations by releasing large numbers of sterile males, which mate with wild females and reduce reproduction. However, existing separation methods typically rely on size differences at the mosquito’s pupal stage, a process that is labor-intensive, difficult to scale, and not fully reliable.

The Hebrew University study, led by Doron Zaada and Prof. Philippos Papathanos of the Department of Entomology, introduces a genetically engineered approach that produces dark-colored males and pale, yellow females. The visible difference allows for rapid and accurate sex separation, a critical step in control strategies that depend on releasing only male mosquitoes into the environment.

The study, published in the peer-reviewed Nature Communications, focuses on the Asian tiger mosquito, Aedes albopictus, an invasive species and a major disease vector worldwide. Using CRISPR gene editing, the researchers disrupted the mosquito’s yellow pigmentation gene, producing albino-like insects. They then restored normal dark pigmentation only in males by linking the pigmentation gene to nix, a key genetic factor that acts as a master switch in male sex determination.

“This produces an engineered sex-linked trait in mosquitoes that uses the insect’s own genes,” Papathanos said. “By understanding and controlling the sex determination pathway, we were able to create a system where males and females are visually different at the genetic level.”

The result is what scientists call a Genetic Sexing Strain, or GSS, in which all males are dark and all females remain pale. Because the difference is visible to the naked eye, the system allows for automated sorting without the need for complex or expensive equipment, making it more suitable for large-scale use.

Beyond simplifying sex separation, the researchers identified an additional safety feature built into the engineered strain. They found that the eggs laid by the yellow females are highly sensitive to desiccation. Unlike wild mosquito eggs, which can survive dry conditions for months, these eggs die quickly if they dry out.

“This acts as a built-in genetic containment mechanism,” Zaada said. “Even if some females are accidentally released, their eggs won’t survive in the wild, preventing any engineered strain containing our system from establishing itself in the environment.”

The study also examined whether genetically converted males retained normal behavior and reproductive capacity. According to the researchers, the engineered males closely resembled natural males in gene expression and mating behavior, suggesting that the approach does not compromise male fitness, a key requirement for successful control programs.

“Our approach provides a versatile platform for mosquito sex separation,” Papathanos noted. “By combining cutting-edge gene editing with classical genetics, we have created a scalable, safe, and efficient system.”

The gene-editing method has practical applications in mosquito control programs that rely on releasing only male mosquitoes. Techniques such as the Sterile Insect Technique require accurate sex separation to avoid releasing biting, disease-transmitting females. By making males and females visually distinct at the genetic level, the system enables fast, automated sorting and improves the reliability of population-suppression efforts.

The approach also simplifies mass rearing and supports industrial-scale mosquito production. Unlike existing methods that are labor-intensive and difficult to scale, visible genetic markers can be identified with simple optical tools, reducing costs. A built-in safety feature, in which engineered females’ eggs die if they dry out, further limits environmental risk and addresses regulatory concerns.

Beyond sterilization-based programs, the platform can be combined with other control strategies, including the release of males carrying Wolbachia bacteria or similar traits. It also allows for future customization, such as making females sensitive to heat or rearing conditions.