The Centers for Disease Control and Prevention estimates that in 2022, around 608,000 people died from malaria, a mosquito-borne disease, worldwide. Add to that, viral infections like dengue, West Nile, yellow fever, Zika, chikungunya, and lymphatic filariasis, mosquitoes kill more people than any other creature in the world.
A recent University of Iowa study may have found a potentially crucial step in controlling the population of the world’s deadliest insect.
The answer? Fruit flies.
The study found that a specific gene, Shal, controls a potassium ion channel in the Johnston’s organ — a key hearing structure in fruit fly’s antenna that fine-tunes how the insect detects sound.
When researchers disabled Shal, fruit flies lost their ability to properly hear and responded less to mating signals. Since mosquitoes have the same gene and use a similar mating process, silencing Shal could disrupt their ability to find mates and reduce mosquito populations.
The study began nearly three years ago, headed by Eli Gregory, an undergraduate research student. Department of Biology Professor Daniel Eberl acted as the corresponding author.
“My whole career, I’ve worked on fruit flies, and because of the genetic tools that are available, we’ve learned a lot about how the antenna works as an ear in the fruit fly,” Eberl said. “We’ve been able to make some applications to mosquitoes that also use the antenna as their ear.”
UI Department of Biology Associate Professor Albert Erives said Shal acts like the more well-known Shaker channel, a type of potassium ion channel that helps regulate electrical signals in neurons. Shal, in particular, appears to have active fine-tuning mechanisms controlling how the mosquitoes detect sound.
“These neurons are mechanically coupled to the rest of the antenna, such as when there’s wind grabbing the antenna or sound because it’s also predominantly an organ of hearing,” Erives said. “It’s at the location in this neuron where that mechanical transduction takes place.”
Eberl reiterated the study itself only blocked the Shal gene in fruit flies, not mosquitoes. The researchers believe the broader impacts of this study could point to blocking the gene in mosquitoes.
Eberl believes with further research, the basis of the study could benefit millions worldwide. As for blocking the Shal gene on a wide scale, he pointed to a professor’s studies in Indiana. They found when gene-targeting machinery was incorporated into yeast, mosquito larvae and adults consumed it and were then incapable of taking a blood meal.
Eberl explained a benefit of blocking the Shal gene, in particular, is that existing mosquito larvae and adults are likely to survive.
“The good thing about that is that ecologically, we’re not really getting rid of mosquitoes altogether,” he said. “Mosquitoes provide food to so many animals along the food chain, right? So many birds and everything, and so those mosquitoes would still be available to provide that sort of service.”
James Lacina, Johnson County Public Health’s environmental health manager, shared the present threat mosquitoes pose in Johnson County.
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Lacina said the findings of the department’s mosquito surveillance program, an annual program run from May through October traps mosquitoes throughout the county to find any carrying diseases like West Nile virus.
“Last year, for example, we collected 2,990 actual mosquitoes,” he said. “We had one detection of West Nile, so that shows that it is present in the mosquitoes here in Johnson County, and that’s exactly why we do the surveillance.”
While no residents contracted the virus, Lacina emphasized the importance of such surveillance to keep Johnson County alert. Public Health would remind residents of the checklist required to remain unbitten.
“Eliminating standing water from tires, gutters, containers, things like that, using EPA-approved insect propellants,” he said. “If you’re going to be exposed to a high-mosquito environment, wear long sleeves and pants during peak mosquito activity, especially if you’re a vulnerable person.”
In light of these mosquito-borne diseases lurking in Johnson County and ravaging other corners of the world, UI researchers are optimistic about what implications further research could bring.
“There’s an immediate potential application here if you interfere with the apparatus for hearing,” Erives said. “The music they listen to are courtship songs, and so if you interfere with this, there’s the potential for interfering with the mating of mosquitoes. That would be a great thing as far as global health concerns.”