Scientists have initiated a "mosquito apocalypse," successfully eliminating 89% of female mosquitoes using a fungus.

A recent study explored an innovative method for combating malaria-carrying mosquitoes using genetically modified fungi that can spread through mating. Conducted by researchers from Burkina Faso and the USA, the study assessed the transmission efficiency and mortality rates of these fungi under laboratory and semi-field conditions. This approach could address several issues related to the spread of this dangerous disease, according to News Medical.

Malaria remains a critical public health issue, affecting approximately 249 million people, with over 608,000 deaths reported in 2022, 80% of which occur in children under five years old.

Traditional measures, such as insecticide-treated nets and indoor spraying, have limitations in combating exophilic (outdoor-resting) mosquito populations, which exhibit behaviors that make them less susceptible to existing strategies.

A potential alternative lies in the use of entomopathogenic fungi—naturally occurring pathogens that kill mosquitoes. However, their effectiveness has historically been hampered by low transmission rates. Advances in genetic engineering have increased the lethality of these fungi by introducing toxins, and a new study published in the journal Scientific Reports under the guidance of Étienne Bilgo, a researcher at IRSS/CNRST and the Muraz Center, focused on their ability to spread through mating to overcome existing challenges.

During the study, two fungal strains—a wild type and a transgenic strain expressing insect-specific toxins—were tested on male Anopheles coluzzii mosquitoes. After treating the males with fungal spores, they were allowed to mate with uninfected females to assess spore transmission, infection levels, and mortality rates.

The results indicated that the transgenic fungi were significantly more effective, causing mortality rates of up to 89.33% in female mosquitoes within two weeks post-mating, compared to 68% in females exposed to the wild-type fungi. The transgenic fungi remained infectious for 24 hours after treatment; however, their effectiveness decreased after 48 hours as infected males began showing symptoms that hindered spore transmission.

The study also confirmed that the primary mode of infection transmission is through mating, rather than surface contact. Environmental factors, such as the positioning of mosquito swarms relative to sunset, influenced mating frequency in semi-field experiments. Nonetheless, the mortality trends mirrored those observed in the laboratory.

It is noteworthy that the fungal spores did not prevent females from mating during the first 24 hours, indicating compatibility with additional mosquito control methods, such as the sterile insect technique (SIT) or Wolbachia-based approaches.

Wolbachia-based approaches are mosquito control methods that utilize Wolbachia, a type of bacteria that infects insects. When mosquitoes are infected with it, their ability to transmit diseases such as malaria, dengue, and Zika may be reduced. This occurs because Wolbachia interferes with the reproduction and replication of viruses within the mosquito's body, making them less effective disease carriers. This compatibility broadens the potential applications of transgenic fungi in integrated vector control programs.

This research holds significant global importance, considering the economic burden of malaria, which costs Africa approximately $12 billion annually due to healthcare expenses, loss of productivity, and impacts on tourism.

By targeting mosquito populations both indoors and outdoors, genetically modified fungi address critical gaps in existing control methods.

However, practical implementation requires addressing challenges such as the declining effectiveness of fungi over time and environmental impacts on mosquito behavior. Preliminary field assessments of mating site dynamics could optimize transmission efficiency and enhance real-world applicability, according to the authors.

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