Researchers have transformed a fungus into a deceptive plant. The modified microbe emits a floral scent, attracting mosquitoes seeking nectar, and exterminates them within days. This remarkably straightforward method has the potential to save countless lives.
This method exploits a fundamental weakness of mosquitoes: their dependence on flowers. While female mosquitoes are notorious for consuming blood, both genders depend on floral nectar as their main food source. An international team of researchers recognized that by making a lethal fungus smell like a meal, mosquitoes would unwittingly march to their demise.
The team, spearheaded by Raymond St. Leger from the University of Maryland, centered their trap around a strain of Metarhizium fungus. After noting that certain wild fungi naturally produce a sweet-scented substance known as longifolene to entice insect prey, they modified their fungus to enhance the output of this chemical. The findings, released on October 24 in Nature Microbiology, essentially showcase a perfume irresistible to mosquitoes.
“After noticing that several varieties of fungi could deceive mosquitoes into perceiving them as flowers, we understood that we could amplify the allure by engineering fungi to generate more longifolene, a fragrant compound that is already prevalent in nature.”
The brilliance of the strategy lies in the fact that longifolene was not previously identified as a mosquito attractant. The researchers allowed nature to provide the clue and then enhanced it through genetic modification. Once the fungal spores are placed in a vessel, whether indoors or outdoors, they emit longifolene consistently for months. Mosquitoes come into contact with the fungus, get infected, and perish within days.
More Effective Than Pesticides
In laboratory evaluations, the fragrant fungus eliminated 90 to 100% of mosquitoes, even when competing with the scent of actual flowers and humans in a spacious area. The results are remarkable, but the safety aspects may be even more noteworthy. Longifolene is already a common component in many commercial perfumes and has a strong history of human safety. The fungus endangers no one but mosquitoes.
Conversely, chemical pesticides have become more challenging over time. Numerous mosquito populations have developed resistance to standard treatments, making them nearly worthless in certain areas. The fungal strategy might completely avoid that issue. If mosquitoes adapt to evade longifolene, they would also lose their attraction to the flowers essential for their sustenance. It’s an evolutionary trap with no clear escape.
St. Leger mentioned that the team has backup strategies if necessary. They could modify the fungus to create additional floral fragrances, providing mosquitoes with several targets to evade. However, he doubts that this will be required. The fundamental reliance on flowers makes resistance improbable.
Inexpensive, Straightforward, and Scalable
A particularly promising feature of the technology is its feasibility. Metarhizium fungi are currently grown worldwide using agricultural waste such as chicken manure, rice husks, and wheat remnants. The production expenses are minimal, and the setup requires no specialized training. Place the container, let the fungus perform its role, and replace it every few months.
“It’s not that you’re guaranteed to discover a universal solution for mosquito control everywhere, but we aim to create a highly varied and adaptable set of tools that individuals in diverse regions can select from.”
The cost-effectiveness might be vital in areas most affected by mosquito-borne illnesses. Malaria alone claims hundreds of thousands of lives each year, predominantly in sub-Saharan Africa. Dengue, yellow fever, and Zika contribute to the death toll. Traditional methods of control, including bed nets and insecticide application, have made progress but continue to be costly and labor-intensive.
St. Leger and his team are currently preparing for larger outdoor trials to gather information for regulatory approval. The immediate target markets include Africa, Asia, and South America. However, he cautions that mosquito-borne diseases might not remain confined to tropical regions for long. Increasing temperatures and unpredictable weather patterns are driving disease-spreading mosquito species into new areas, including parts of the United States that have never experienced them before.
The fungus with a floral scent is just one option among many, as emphasized by St. Leger. Different regions will require tailored strategies based on local mosquito varieties, environmental factors, and available resources. The aim is not to identify a singular optimal solution but to provide communities with choices. In this scenario, the choice is a pleasant-smelling fungus that effectively eliminates its targets.
<a href="https://doi.org/10.1038/s41564-025-02155-9