Calif. Legislature bites back at GE mosquito releases

Members of California’s state legislature pushes the Department of Pesticide Regulation to deny the approval of Oxitec’s lab-made, non-biting mosquitoes

SACRAMENTO, CALIF. – A biotech company created millions of genetically modified mosquitoes, but not in the Jurassic Park sense. The lab grown species could actually lower the population of an invasive mosquito that carries a plethora of diseases on its shoulders.

On Nov. 3, several members of the California legislature sent a letter to the Department of Pesticide Regulation (DPR) asking it to delay the release of millions of genetically engineered (GE) mosquitoes in Tulare County by Oxitec, a British biotech company, in the interest of further regulatory review. 

The GE mosquitoes are meant to lower the population of Aedes aegypti, an invasive mosquito that has been plaguing communities in the county for the last few years. However, members of the legislature are pushing for the DPR to resist the GE mosquitoes because of unforeseen effects they might have on people and the environment.

This would be the first experimental release of of the non-biting mosquitoes, which OxiTec calls “friendly mosquitoes,” in Tulare County. Though the U.S. Environmental Protection Agency approved the release of the mosquitoes on March 7, the agency has been awaiting approval from DPR for several months, even after a 15-month scientific evaluation process and a 15-day public comment period that ended on April 19.

“There are too many unknown factors when it comes to how it could affect our biodiversity in the long run, including how this might influence populations of birds, bats, fish species and other insects,” according to Assemblymember Laura Friedman (D-Glendale) via a statement. 

If DPR approves Oxitec’s mosquito project, California would be only the second U.S. state after Florida where GE mosquitoes could be experimentally released—with the potential to ultimately be the site of the largest mass release to date, according to the California Food and Safety Department. 

“We are pleased to see leaders from our state legislature taking action to protect public health and the environment from the unknown impacts of GE mosquitoes,” according to Rebecca Spector, west coast director at Center for Food Safety via a statement. “They rightfully are asking DPR to conduct a more comprehensive review and public meetings for residents that will be impacted, before approving this permit.”

The mosquitoes were engineered by Oxitec with a self-limiting gene that infects female mosquitoes and prevents them from creating female offspring, leaving only male mosquitoes in the gene pool. Only female mosquitoes bite and are capable of transmitting diseases, which is why they are targeted and the engineered males will only mate with Aedes aegypti females. The altered mosquitoes also have a fluorescent marker gene which enables them to be distinguished from invasive mosquitoes for effective monitoring.  The self-limiting gene cannot establish in the ecosystem and does not impact non-target species, such as bees, butterflies and other wildlife.

The Delta Mosquito and Vector Control District based in Visalia was approved for the  pilot project to release the lab-grown mosquitoes after inviting Oxitec to Tulare County. Oxitec has applied for up to 48 test release sites in Visalia for unspecified areas within 5,000 square miles, according to the EPA. There will be 5,000-30,000 mosquitoes released per site every week, according to the press release.

Florida was the first state to get involved with OxiTec’s pilot program, with the EPA approving the release of the GE mosquitoes on March 8, 2022 and by the Florida Department of Agriculture and Consumer Services in May. The Florida Keys Mosquito Control District continued the release of the mosquitoes on Sept. 16. This is the third phase of mosquito releases, with the first release being in May. OxiTec reported that the number of GE mosquitoes that will be released across all three of Florida’s 2022 phases is estimated to be seven million. 

Though data of the GE mosquitoes effectiveness is not yet known in Florida, there were multiple releases that happened in Brazil years earlier. Independent researchers from Yale University were able to measure the effectiveness of the GE mosquitoes in Brazil, since they began experimenting there the longest. The study found that the GE mosquitoes failed to reduce populations of Aedes aegypti. The Yale study also found that the GE mosquitoes bred with local Aedes aegypti, resulting in hybrid mosquitoes in the wild that may be more aggressive, more difficult to eradicate and may increase the spread of mosquito-borne disease.

OxiTec, however, states on their website that their mosquitoes are “safe, sustainable, and harmless to the local ecosystem, including beneficial insects like bees and butterflies.” 

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