Google is currently waiting for approval from the EPA to deploy 64 million sterilized male mosquitoes in California and Florida over a two-year period. The goal is to tackle the population of the southern house mosquito, which is linked to disease transmission.
The initiative, known as Debug, targets the species Culex quinquefasciatus. This species is associated with illnesses like St. Louis encephalitis and West Nile virus, which collectively affect over 1,300 individuals in the United States annually.
Now, some might think that using more mosquitoes to control a mosquito problem seems counterintuitive. But it’s actually a practical approach. Male mosquitoes, unlike females, do not bite humans, so they can’t spread diseases.
These male mosquitoes have been treated with a common bacterium called Wolbachia, rendering them unable to reproduce. When they mate with females that lack this bacterium, the resulting eggs simply won’t hatch—leading to fewer mosquitoes over time.
According to the CDC, Wolbachia doesn’t harm humans or animals, and it’s important to note that these mosquitoes are not genetically modified.
There are various methods to combat mosquitoes, and Debug operates using a strategy called the suppression method.
How the introduction of Wolbachia-laden mosquitoes can diminish mosquito populations and curb disease spread
In the first year of the project, approximately 16 million lab-bred and sterilized male mosquitoes would be released in both Florida and California, followed by another 16 million in the second year, as outlined in a notice published in the Federal Register.
The notice, however, doesn’t specify the exact locations or timelines for these releases.
Only female mosquitoes bite since they require blood to produce eggs, while males thrive on nectar from flowers.
What effect does Wolbachia have on mosquitoes?
While Debug employs a suppression method, the World Mosquito Program takes a different approach known as the replacement method. In this method, populations of mosquitoes are replaced with those carrying Wolbachia, leading to mosquitoes that are incapable of transmitting diseases.
Gregor Devine, the senior scientific director of the World Mosquito Program, mentioned that Wolbachia benefits mosquitoes in two significant ways:
- The bacteria enhances the mosquito’s immune system, making it less favorable for viruses like dengue, Zika, chikungunya, or yellow fever to thrive.
- Wolbachia competes with viruses for essential nutrients, making it more difficult for those viruses to proliferate, thus reducing transmission.
The CDC notes that Wolbachia is commonly found in insects worldwide and decomposes alongside them when they die.
This method works on a species-specific basis, having been applied to creatures like fruit flies and codling moths.
While Debug focuses on Culex quinquefasciatus, it has also been effective with Aedes aegypti mosquitoes to disrupt their reproductive patterns. Aedes aegypti mosquitoes, known for spreading diseases like yellow fever, dengue fever, and Zika, are recognized for their impact on public health.
Interestingly, while the use of Wolbachia against Aedes aegypti mosquitoes has shown success in places like Texas, California, Singapore, Thailand, Mexico, and Australia, there is a caveat. If the releases stop, the Aedes aegypti populations can increase again.
How is this bacteria utilized?
The CDC explains the process as follows:
- Wolbachia bacteria are introduced into male and female mosquito eggs of the same species.
- These eggs produce both male and female mosquitoes that are then mass-bred in a facility.
- Only the males are selected for release, while females may be retained for further breeding.
- The male mosquitoes with Wolbachia are introduced into the environment.
Even though using this bacteria is generally seen as more eco-friendly compared to pesticides, the overall strategy relies heavily on efficiently isolating, sterilizing, and releasing a sufficient number of male mosquitoes. Lots of logistics are involved, including chilling, packing, and transporting these insects.
Efficacy can wane in areas with dense populations of targeted mosquitoes, necessitating repeated releases.
Members of the public can provide feedback on the EPA’s proposal until June 5.
