Season 17, Episode 49: How Scientists Are Trying to Eliminate Mosquitoes

Hey StarTalkians! Episode 49 of season 17 switched astronomy for entomology, as Neil and Negin sat down with entomologist Dr. Jessica Ware to discuss all things bugs. I was pretty surprised to hear any biologist support the eradication of any species, but Dr. Ware did so for two mosquito species:

It’s Bugs’ World and We’re Just Living In It with Jessica Ware - StarTalk Radio

(from 37 minutes)

She even mentions a couple of methods scientists have tried. But would they work? Why is there apparently little concern about the ecological consequences?

The Mosquitoes That Kill

It’s not all mosquitoes! The Anopheles gambiae complex – actually seven very similar species – and Aedes aegypti are the main vectors for dengue fever, malaria, yellow fever and chikungunya, and therefore a common target of these efforts.

Irradiated Mosquitoes

As Dr. Ware mentioned, one of the most common methods tried so far releases sterile males into the population to mate and reduce the number of offspring in the next generation.

One test of this in Brazil sterilized the males with radiation, and then released them into the wild population using drones. This was effective, and as a different, self-explanatory paper emphasized, “Yes, Irradiated Sterile Male Mosquitoes Can Be Sexually Competitive!”.

The Bacteria Method: Wolbachia to the Rescue?

Another approach Dr. Ware mentioned involves bacteria called Wolbachia pipientis and targets the A. aegypti mosquito. Specifically, if they are infected with some strains, it prevents viruses such as dengue from growing in their bodies.

A randomized trial released wolbachia-infected mosquitoes into 12 randomly-chosen urban subdivisions in Indonesia. The remaining areas continued practicing ordinary mosquito control measures. They checked people with fevers presenting to government-run health clinics to see if it reduced dengue infection.

They found that people in areas with infected mosquitoes were significantly less likely to be diagnosed with dengue (2.3% vs. 9.4%), and were also less likely to be hospitalized.

Would it Effect the Ecosystem?

As a paper looking at this concluded, for the A. gambiae mosquitoes, most predators that eat these mosquitoes would likely easily substitute other food sources if they were removed. While the Wolbachia method would probably be ecologically benign – since the population is maintained – even population reduction in targeted species seem like it would have minimal impact.