Google is pushing an experiment to release up to 64 million mosquitoes in California and Florida. The goal is not to increase mosquitoes that bite people, but to curb populations of disease-carrying mosquitoes.
The U.S. Environmental Protection Agency (EPA) said in May that it is reviewing Google's application for an experimental mosquito release permit. If approved, Google could release up to 32 million male mosquitoes each in California and Florida for two years, for a total of 64 million. The EPA plans to decide on final approval after gathering public comments.
◇ Release bacteria-infected male mosquitoes to block reproduction
The plan is part of Google's Debug project. Debug is a project to mass-rear male mosquitoes and release them outdoors to reduce populations of mosquitoes that spread disease. In the process, Google uses artificial intelligence (AI), automation equipment, and sensor technology to rear mosquitoes and select only non-biting males for release.
Bradley White, lead researcher for Google's Debug initiative, said on social media that more than 4 billion people worldwide are at risk of mosquito-borne diseases and that urbanization and the spread of vector mosquito species are increasing the risk of infectious diseases.
The target species for this experiment is the southern house mosquito (Culex quinquefasciatus), known to transmit West Nile virus and St. Louis encephalitis, among others. In the United States, West Nile virus is considered a representative mosquito-borne infectious disease.
Google's core technology uses a bacterium called Wolbachia pipientis. Wolbachia is a symbiotic bacterium found in many insects in nature that alters genes in male sperm to block reproduction. When a Wolbachia-infected male mates with an uninfected wild female, even if fertilization occurs, the embryo does not develop normally and the eggs do not hatch.
Google plans to infect non-biting males with the bacterium, release them in large numbers to mate with wild females, reduce the number of viable eggs, and lower mosquito populations.
◇ Scientists say it is more targeted than insecticides… but monitoring is needed
Scientists say the approach could pose less environmental burden than traditional insecticide-centered control. Insecticides can affect other insects besides mosquitoes, and long-term use can create resistance in mosquitoes.
Kartikeyan Chandrasegaran, a professor at the University of California, Riverside, told Live Science that Wolbachia-based strategies are generally species-specific and do not introduce new toxic substances into the environment, adding that from that standpoint they are a relatively conservative option among currently available mosquito control tools.
Eric Caragata, a professor at the University of Florida, also said that efforts to reduce mosquito populations by using Wolbachia-infected males have been underway in various regions since around 2011.
Still, there are some concerns. Chandrasegaran noted that large-scale ecological interventions require ongoing observation, because other mosquito species could occupy the niche after a particular species declines.
He said most predators that eat mosquitoes are generalist predators that also consume various aquatic and terrestrial insects, and there is little evidence that a decline in the southern house mosquito would trigger major ecological cascade effects. He added that if population suppression is achieved safely and sustainably, the public health benefits are likely to far outweigh the ecological risks.
White addressed concerns about Debug, saying that over the past 10 years the team has carried out large-scale control programs on four continents and reduced populations of disease-carrying female mosquitoes by more than 90%. All programs are conducted in collaboration with local health authorities and government agencies and are designed to complement existing local control efforts.