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Mosquitoes in southern regions spread West Nile virus and other diseases. | Source: Smith Collection/Gado/Getty Images
Google plans to release 64 million bacteria-infected mosquitoes in California and Florida, but scientists aren't worried.
The Environmental Protection Agency (EPA) is reviewing a tech giant's application for an experimental permit to release mosquitoes that, paradoxically, could lead to a reduction in the population of disease-carrying mosquitoes.
The release is part of Google's Debug initiative, which aims to release millions of non-biting male mosquitoes infected with the bacterium into the environment. Wolbachia pipientis (commonly known as Wolbachia ) . This bacteria does not harm infected males, but it prevents uninfected females with whom they mate from producing offspring, thereby dramatically reducing the mosquito population over time.
In this case, Google is targeting southern house mosquitoes ( Culex quinquefasciatus ), an invasive species found in tropical and subtropical regions that can spread diseases such as West Nile virus and St. Louis encephalitis to humans.
The proposal has generated considerable enthusiasm among scientists. Karthikeyan Chandrasegaran, an associate professor at the University of California, Riverside, who studies mosquito ecology and behavior in the context of public health, told Live Science that the use Wolbachia bacteria is a "smart" approach to mosquito control, especially when compared to the use of broad-spectrum insecticides.
«"Strategies based on Wolbachia bacteria, are generally species-specific and do not introduce new toxins into the environment," Chandrasegaran said. "It is important to note that Wolbachia "They are already widespread among many insect species and are a natural bacterial symbiont, not a genetically modified organism. From this perspective, they are among the most environmentally friendly mosquito control methods currently available.".
The Environmental Protection Agency (EPA) has deemed Google's request potentially significant at the regional and national level and will make a final permit decision after a public comment period that ends on June 5. After that, the agency may grant Google permission to release up to 32 million mosquitoes in California and another 32 million in Florida over two years.
However, despite the scale of the proposed releases, Google's approach is not new and has already proven effective against another type of mosquito.
«"This is a method that has been actively used for mosquito control since about 2011," Eric Karagata, an assistant professor at the University of Florida who studies mosquito control, told Live Science. Wolbachia bacteria to fight mosquitoes.
Fighting mosquitoes with mosquitoes
According to the Centers for Disease Control and Prevention (CDC), mosquitoes are the most deadly animals on the planet, killing between 500,000 and over a million people annually by spreading dangerous diseases. Given that these bloodsuckers are so small, widespread, and numerous, reducing their population on a large scale is a challenging task. The use of insecticides can harm the environment and decimate other pollinators, and mosquitoes are increasingly developing resistance to them.
«"We are constantly fighting both mosquito-borne diseases and insecticide resistance," Karagata said.
Wolbachia bacteria offers a potential natural solution to the mosquito problem. This bacterium is widespread among insects but does not infect other animals, such as humans. Through a process called cytoplasmic incompatibility, the bacterium creates a unique interaction between infected males and uninfected females.
Bacterium Wolbachia pipientis may prevent southern house mosquitoes from producing viable offspring. The mosquitoes are pictured in the pupal stage. | Source: Smith Collection/Gado/Getty Images
In males Wolbachia bacteria modifies the genome of sperm in such a way that embryos formed using these sperm die. However, if the female also has Wolbachia bacteria , and it is present in the embryo, then damage to the sperm genome causes no harm. This interaction means that if millions of infected males are released into the population, uninfected females will mate en masse with them and will be unable to produce viable offspring.
«"If a female mosquito has Wolbachia bacterium, She can successfully mate and reproduce with both infected and uninfected males,» Karagata said. «All of her offspring will have Wolbachia bacteria . However, if you have an uninfected female mosquito and she mates with a male mosquito infected with the bacteria Wolbachia , none of her offspring will hatch.".
Google is building machines that autonomously breed millions of infected mosquitoes and then, using artificial intelligence (AI) algorithms, sensors, and other engineering solutions, separate the males from the females.
Researchers have been using sterilized male mosquitoes to reduce their populations for decades. Female mosquitoes bite people because they require protein and other nutrients in blood to lay eggs, while male mosquitoes obtain all the necessary nutrients from the nectar of flowers and fruits, not from humans. Therefore, releasing male mosquitoes theoretically poses no threat to humans.
Most previous attempts at mosquito control genus Aedes aegypti , which carry diseases such as the Zika virus and dengue fever, have focused on these insects. In Singapore, where Google also operates, researchers are using males infected with the bacteria. Wolbachia, to combat dengue fever. Trials have shown that this approach reduces the vector population by 90%, and, accordingly, the risk of human dengue infection by 70% (TP3). However, Google's large-scale fight against southern house mosquitoes is a new approach.
More advantages than disadvantages.
Although some factors remain unknown, no significant ecosystem disruptions are expected in either Karagat or Chandrasegaran. Many animals feed on mosquitoes, but a sudden decline in the southern house mosquito population should not lead to starvation of large numbers of animals.
«"Most mosquito predators are omnivorous and consume a wide range of aquatic and terrestrial insects," Chandrasegaran said. "Therefore, there is little evidence that localized population suppression Culex quinquefasciatus will cause significant environmental consequences.".
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Chandrasegaran noted that ecosystems are complex, so any large-scale intervention should be monitored. One potential consequence could be that the decline of one mosquito species could create space for another, but Chandrasegaran believes the benefits will likely outweigh the drawbacks.
«From a public health perspective, the reduction in numbers mosquito Culex quinquefasciatus "This species is an important vector for West Nile virus and a number of other pathogens, and could provide significant benefits," Chandrasegaran said. "If suppression can be achieved safely and sustainably, based on our current knowledge, the public health benefits are likely to outweigh the environmental risks.".
In the United States, West Nile virus is the leading cause of mosquito-borne illness. According to the CDC, approximately 2,000 people become infected with the virus each year, and many more likely remain undiagnosed. Most people experience no symptoms, and some experience mild flu-like symptoms; however, in some cases, it can lead to severe illness and death. In California, more than 8,000 human cases of West Nile virus infection and over 400 deaths have been reported since 2003—none so far this year.
Internationally, mosquitoes genus Culex , such as C. quinquefasciatus , also play a significant role in the spread of the Japanese encephalitis virus, a problem in Asia. The World Health Organization (WHO) estimates that approximately 100,000 cases of Japanese encephalitis are reported annually, with mortality rates reaching 30%.
Live Science reached out to Google for comment and received a link to a public statement regarding the Debug project.