Mosquitoes spread many deadly diseases, including malaria, and scientists have long been searching for ways to treat or stop such diseases. However, preventing mosquito bites is still the best way to prevent illnesses that are carried by mosquitoes. Advanced technologies could open up new avenues to stopping mosquito-borne diseases. These include genetically engineering mosquitoes to stop them from reproducing, or, as a new study has suggested, attracting mosquitoes to a fungus that will kill them. In a new study reported in Nature Microbiology, researchers have developed a fungus that takes advantage of the natural attraction that mosquitoes have to flowers;
In this study, the scientists engineered a strain of Metarhizium fungus that has a floral scent, because it emits a sweet smelling molecule called longifolene. The fungus can be put into containers and left indoors or outdoors, where they start emitting longifolene, and continue to do so over months. When mosquitoes are exposed to this fungus, the insects are infected by it, and die within days.
The investigators showed that 90 to 100% of mosquitoes are infected and killed within days of encountering the fungus, which is harmless to humans. Mosquitoes were attracted to it even when they were in an environment with other attractive scents like other flowers and humans.
"Mosquitoes need flowers because they provide nectar, a crucial source of food for them, and they are drawn to flowers through their scents," explained study co-author Raymond St. Leger, a Professor at the University of Maryland.
The researchers observed that some kind of fungi that smell like flowers were attractive to mosquitoes, and they were inspired to “turbocharge the attraction by engineering fungi,” so they’d make more longifolene. “Before this study, longifolene wasn't known to attract mosquitoes. We're letting nature give us a hint to tell us what works against mosquitoes,” said St. Leger.
Previous work has already established that both this fungus and longifolene are harmless to humans, added St. Leger. "This makes it much safer than many chemical pesticides. We've also designed the fungus and its containers to target mosquitoes specifically rather than any other insects and longifolene breaks down naturally in the environment."
It would be challenging for mosquitoes to evolve resistance to longifolene, since they would probably stop repsonding to flowers in general. But since they need flowers to survive, "it would be very interesting to see how they could possibly avoid the fungus yet still be attracted to the flowers they need," said St. Leger. "It'll be very difficult for them to overcome that hurdle, and we have the option of engineering the fungus to produce additional floral odors if they evolve to specifically avoid longifolene."
Now the researchers are working on more trials. They hope to develop these findings into something that can be applied to mosquito control. Metarhizium is also simple and inexpensive to produce.
"It's not as if you're going to necessarily find a silver bullet to control mosquitoes everywhere, but we're trying to develop a very diverse and flexible set of tools that people in different parts of the world can use and choose from," St. Leger said. "Different people will find different approaches work best for their particular situation and the particular mosquitoes they're dealing with. In the end, our goal is to give people as many options as possible to save lives."
Sources: University of Maryland, Nature Microbiology