Researchers have engineered a mosquito-killing Metarhizium fungus that emits a flower-like scent, longifolene, to draw in the insects and infect them. The work, published October 24, 2025, in Nature Microbiology, could provide a safe, affordable complement to chemical pesticides amid rising mosquito-borne disease, the team says. ([doi.org](https://doi.org/10.1038/s41564-025-02155-9))
An international research team that includes Raymond St. Leger, a Distinguished University Professor of Entomology at the University of Maryland, reports that a modified strain of Metarhizium fungus can mimic floral odors to attract mosquitoes and kill them after contact. The paper lists collaborators from multiple institutions and countries. (doi.org)
How it works
- The scientists identified longifolene—a natural plant-derived scent—as a key attractant released by fungus-colonized insect cadavers, then engineered the mosquito pathogen Metarhizium pingshaense to produce more of the compound. In controlled tests, spores placed in simple containers released the scent over months, drawing mosquitoes to land and become infected. (doi.org)
- The Nature Microbiology study found that the engineered fungus attracted and killed male and female Aedes albopictus, Anopheles sinensis, and Culex pipiens. Attraction was not diminished by human odor; flowering plants could compete for attention, but mortality still exceeded 90%. (doi.org)
What the tests showed
- Laboratory experiments reported mosquito kill rates of roughly 90–100%, even amid competing human and floral scents in large-room trials, according to the University of Maryland summary of the work. (cmns.umd.edu)
Safety, resistance and specificity
- The researchers say the approach is “completely harmless to humans,” noting that longifolene is already used in perfumes and has a long safety record. They add that the formulation and containers are designed to target mosquitoes, and that longifolene degrades naturally. Independent regulatory reviews would still be required before deployment. (cmns.umd.edu)
- Because mosquitoes rely on floral cues for nectar, the team argues it may be harder for them to evolve around this lure; if needed, additional floral odors could be engineered into the fungus. (cmns.umd.edu)
Cost and scalability
- Production could be inexpensive and locally scalable, the team notes, because Metarhizium can be cultivated on low-cost agricultural byproducts such as chicken droppings, rice husks, and wheat scraps. (cmns.umd.edu)
Climate context and next steps
- "Mosquitoes love many of the ways we are changing our world," St. Leger said, warning that warming and shifting weather patterns are expanding mosquito habitats and disease risks, including to parts of the United States. (cmns.umd.edu)
- The researchers are pursuing larger-scale outdoor trials and preparing materials for regulatory submissions. Their goal, St. Leger said, is not a single solution but a broader toolkit alongside nets, insecticides, and other biological controls. (cmns.umd.edu)