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Mediterranean bacteria show potential as new mosquito biopesticides
Last reviewed: 15.07.2025
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Mosquito-borne diseases kill more than 700,000 people each year, according to the World Health Organization, and the mosquitoes that spread them are extremely difficult to control. Most species have developed resistance to all major classes of synthetic insecticides, many of which pose health and environmental risks.
Biopesticides derived from living organisms could help overcome resistance to chemical insecticides and offer an environmentally friendly way to control pests. This week in Applied and Environmental Microbiology, researchers reported that bacterial isolates collected on the Mediterranean island of Crete act as insecticides against Culex pipiens molestus mosquitoes, which can transmit human pathogens such as West Nile virus and Rift Valley virus. In laboratory tests, extracts containing metabolites produced by three of the isolates killed 100 percent of mosquito larvae within 24 hours of exposure.
“These metabolites could be the basis for developing biopesticides with minimal environmental side effects,” the scientists note.
“They degrade more quickly in the environment, do not accumulate, and generally do not kill a wide range of different insect species, as chemical insecticides do,”
explains George Dimopoulos, PhD, a molecular entomologist and microbiologist at Johns Hopkins University in Baltimore and the Institute of Molecular Biology and Biotechnology (IMBB) in Crete.
Discovery in Crete and the MicroBioPest project
The new study was led by Dimopoulos and molecular biologist John Vontas of IMBB as part of the European Union-funded MicroBioPest project.
The researchers collected 186 samples from 65 different locations across Crete, including topsoil, soil around plant roots, plant tissue, aquatic samples, and dead insects. They then exposed C. pipiens molestus larvae to aqueous solutions containing the most promising isolates.
- More than 100 isolates destroyed all mosquito larvae within 7 days.
- Of these, 37 isolates destroyed larvae within 3 days.
- These 37 isolates represented 20 different genera of bacteria, many of which had not previously been considered as potential biopesticides.
Further analysis showed that the fast-acting bacteria killed the larvae not by infecting them, but by producing compounds such as proteins and metabolites.
"This is encouraging because it suggests that an insecticide based on these bacteria would not rely on the microorganisms remaining alive," Dimopoulos said.
What's next?
The scientists are now studying the chemical nature of the insecticidal molecules in more detail, determining whether they are proteins or metabolites. They are also testing the range of insecticidal activity of these bacteria, including tests on other species of pathogen-carrying mosquitoes and agricultural pests.
“Biopesticides often degrade quickly and require multiple applications,” says Dimopoulos. “Finding the right way to formulate and deliver these compounds will be a major challenge in the future.”
The new study represents a phase of discovery.
"We are now moving to the basic science of studying the chemical structures and mechanisms of action of molecules, and then we will move to the applied direction, trying to create prototypes of products. There is now a serious impetus for the development of environmentally friendly insecticides," he added.