The Aedes aegypti female mosquito. Credit: Centers for Disease Control Credit: Centers for Disease Control (CDC)

Judith Pierce, public outreach coordinator for the Alameda County Mosquito Abatement District, would like to make one thing clear: A release of genetically engineered mosquitoes is not coming to Berkeley — or anywhere in Alameda County — in the near future. Not to her knowledge, anyway, and if it were official, she would know. 

The Berkeley City Council’s robust discussion of this at a council meeting in early November was based partially on misleading information, said Pierce.

The council, at its Nov. 9 meeting, considered whether to send a letter to the Environmental Protection Agency (EPA) opposing a potential California pilot study of mosquitoes engineered to combat Zika, dengue, chikungunya, yellow fever and other diseases.

Councilmember Ben Bartlett sponsored the item, sending out an email to constituents ahead of time urging them to take action to prevent the EPA from “releasing billions of genetically engineered mosquitoes across California, specifically in Alameda County.” The sample letter Bartlett presented to the council was focused statewide, but background information he shared, as well as discussion at the meeting, focused on keeping the mosquitoes out of the county.

During the meeting he moved the item from the automatically approved consent calendar to a discussion item, calling the matter urgent. “Apparently, we are on the verge of hosting the largest genetically engineered mosquito release in human history,” he said.

It’s true that an international company called Oxitec has applied to the EPA for a California pilot of its genetically modified Aedes aegypti, or Egyptian mosquitoes, designed to reduce its populations. But even if the pilot is approved, Pierce said neither Berkeley nor anywhere else in Alameda County is slated for the study.

Oxitec’s trademarked “Friendly” mosquito is a male Aedes aegypti engineered to pass along a gene that shrinks the lifespan of female offspring so they die as larvae, before they start biting or feeding. 

The district did, however, join other counties in sending the EPA a letter of general support for the pilot in the interest of learning more about the potential of the technology, which it sees merit in, Pierce said. “We know that Aedes aegypti is very, very difficult to eradicate once it comes into a community and we know that our current methods are insufficient,” she said.

The letter does not mention plans to release Aedes aegypti mosquitoes in Alameda County. “We signed on because we were interested in learning more about it,” Pierce said. “It’s kind of like having a seat at the table.”

Oxitec’s new gene-targeting strategy for tackling a mosquito that transmits several serious illnesses has sparked international controversy with questions around its safety. But the company has already won EPA approval for field testing in Florida, now underway. And the Brazilian government has backed its use there, where Oxitec’s work is expanding. 

Aedes aegypti exists in California, but has not yet been found in Alameda County. Native to Africa, the disease-transmitting insects are spreading globally at a rate alarming public health experts. Many blame this growth on climate change.

“In order to have those pilot projects go to your county, you have to have a certain amount of pest pressure, or a certain number of those mosquitoes. Alameda County does not have that,” Pierce said.  “We’re kind of looking into the future and we’re trying to determine which tools we can use in case they [Aedes aegypti] do come here.” 

A few weeks ago, Alameda County was listed among the California counties in the potential study area on the Oxitec website — possibly related to the letter.

Today, however, the county isn’t mentioned. In fact, the company’s California pilot pages don’t refer to any counties specifically, though they include a California Department of Public Health map of where Aedes aegypti is found in the state. 

Joshua Van Raalte, of Oxitec, referred questions on which counties are targeted for the California pilot to the Mosquito Vector and Control Association of California, which advocates for the state’s 60-plus local mosquito control districts.

Lisa Yarbrough, a spokesperson for the association, which supports the pilot, said she doesn’t know yet which counties will be included if the EPA grants approval. “But Oxitec has indicated that it will initiate a pilot project in one or two communities,” she said.

Newness fuels confusion 

A colony of Aedes aegypti from the Central Valley. Credit: University of California Agriculture and Natural Resources

Bartlett’s misunderstanding appears linked to confusion around the letter, as well as the approval process for Oxitec’s California pilot — familiar ground for a company whose science doesn’t fit neatly into a standard regulatory pocket, as with a pesticide that’s sprayed or an insect repellent that’s applied to the skin.

“It’s in a kind of strange zone for lots of us,” Pierce said. Local mosquito districts, such as Alameda County’s, are waiting to hear more from the state, she said. “We have advocates and local officials trying to understand this process. … We’re all somewhat in the same boat.” 

Bartlett’s report to the City Council said the EPA approval could come in mid-November, with the state approval weeks after. But these dates passed. 

“EPA has not given any public indication of its decision timeline, so as a concerned community member, I am left hanging with little information,” said Dana Perls, food and technology program manager of Friends of the Earth. 

The nonprofit is leading opposition to the pilot, joined by other groups. Perls lives in Bartlett’s South Berkeley district and brought the issue to his attention.

“[We don’t] want to see these GE mosquitoes released anywhere. … Mosquitoes don’t recognize county lines.” — Dana Perls, Friends of the Earth

Much of Bartlett’s background information on the issue was provided by Friends of the Earth, he said. 

Perls said the organization’s attention on Berkeley stemmed from the support letter signed by the Alameda mosquito district. 

“Based on the only publicly accessible information, we took action and began reaching out to people in the districts listed in the letter,” she said. (The other districts that signed: Shasta, Coachella Valley, Orange County, Consolidated (Fresno County), West Valley (San Bernardino County), East Side (Stanislaus County), Greater Los Angeles, Delta, and Sacramento-Yolo.) 

“Friends of the Earth doesn’t want to see these GE mosquitoes released anywhere. This is not just about Alameda County. Mosquitoes don’t recognize county lines,” Perls said. 

The City Council ultimately agreed unanimously to seek more information on the issue, and not send a letter against the pilot. That’s the decision that Pierce, along with other members of the abatement district who attended the remote meeting, had recommended. 

Perls said she was disappointed in the meeting’s outcome, but Bartlett said he thinks it went well. “I’m satisfied,” he said last week. “It was a great learning experience.”

Calling himself an “on-ramp” for the community to government, he said the discussion was a needed public service for a cloudy issue. “It was helpful that the abatement district came out,” he said. “They were great.” 

When asked if he thought he had misled residents by saying the mosquitoes could soon be released in Berkeley, he said this was his impression from the advocates.

He said his office tried to contact the EPA and Oxitec multiple times for details, with no success. He thanked Friends of the Earth for bringing the matter to his attention.

“I don’t implicate the science at all,” he said. “Community members wanted to have a hearing, so I helped them do it.”

The so-trademarked ‘Friendly’ mosquito  

An Oxitec mosquito release box, being piloted now in Florida and Brazil. Credit: Oxitec

Founded in 2002 as a startup affiliated with Oxford University, Oxitec, a private bioengineering company now owned by Precigen (formerly Intrexon) is working on alternatives to chemical pesticides for problem insects threatening humans and agriculture. The company and its work are at the center of vigorous debate around applying genetic engineering to problems of the natural environment.

A strong focus of Oxitec is its trademarked “Friendly” mosquito, a male Aedes aegypti engineered to pass along a self-limiting gene that shrinks the lifespan of female offspring so they die as larvae, before they start biting or feeding. 

Only female mosquitoes feed on blood or bite. Males eat nectar.

Without females for mating mosquito populations dwindle, according to Oxitec. The effect is passed on through the modified males for “multiple” generations but eventually declines, the company says.

The modified mosquitoes also carry a florescent marker gene that makes them glow under a special light so they can be tracked after release.

To survive in the lab, mosquitoes are fed the antibiotic tetracycline, which turns off the early death gene.

Sometimes called “ankle biters,” the small black and white Aedes aegypti are known as aggressive feeders, active in the daytime and adapted to urban environments. As with other mosquitoes, research shows they’re developing a resistance to insecticides or pesticides.  

The vector is now found on all continents except Antarctica, including in the United States, mainly in the warmer, southern parts of the country. As it spreads, so do the diseases it transmits. 

The lifetime flight range of Aedes aegypti is estimated at 150 to 500 feet. But the insects are known to stow away on ships, according to the European Centre for Disease Prevention and Control, crossing continents and countries.  

In California, Aedes aegypti is found throughout central and southern California. But to date, the insect isn’t suspected of spreading illness within the state, according to the California Department of Public Health. The few cases of Zika and dengue fever diagnosed here are linked to bites outside of the country. 

Still, public health officials are carefully watching the species as its habitat grows. 

“Friendly” mosquito technology is being used in Brazil, and Oxitec just finished a mosquito release phase of its pilot project in Florida. The company is seeking EPA approval to expand its Florida pilot, along with adding California and Texas. 

Genetic engineering hits a nerve 

Oxitec and its “Friendly” mosquitoes are contentious in a vein similar to the response to genetically modified foods. Critics claim the research on safety is insufficient. Supporters challenge this, calling the approach innovative and the science sound. Passions on both sides flame. 

A Donald Trump-allied Oxitec lobbyist and an Oxitec-critical journal article deemed problematic by its editors after publication are mired in the debate. And in a twist, Ed Russo, one of the leading critics of the pilot in Florida is an environmental advisor to Trump who wrote a book lauding the former president.

Objectors’ concerns, among other things, are that the effects of released mosquitoes on the health of humans and other animals aren’t fully understood, including what could happen if some females live to bite. They question if the lab-grown mosquito’s diet of tetracycline might have a lingering negative impact in the outside world. And they wonder what type of mosquito might swarm in to fill the void left by Aedes aegypti. 

The EPA maintains confidence in its review of the safety of the approach, saying it’s thoroughly examined these issues. 

Local division on the issue mirrors that occurring in other places.

“It’s problematic for a district to support a mass open-air genetic experiment in our state,” said Perls, of Friends of the Earth. 

“This trial proposal is riddled with missing information and information critical for public review is withheld from the public and protected as confidential business information,” she said. 

Van Raalte, the Oxitec spokesperson, said the company’s website cites over 100 peer-reviewed studies and provided a link to the company’s California webpage. 

“Health impact studies are only possible at very large scales and we are only in the process of our first small pilots as part of an EUP [EPA experimental use permit] in the U.S.,” he said. 

A complicated approval process 

Inspecting a mosquito trap. Credit: Centers for Disease Control

It took 10 years for Oxitec to get federal approval for its “Friendly” mosquito pilot in Florida, granted by the EPA in 2020. 

Approval starts with an EPA experimental use permit then moves to the state and local levels. If the EPA greenlights Oxitec’s expansion to California, the California Department of Pesticide Regulation (DPR) weighs in next, said Erika Castillo, regulatory and public affairs director for Alameda County’s mosquito district.  

Leia Bailey, a spokesperson for the state pesticide regulation department, said it hasn’t heard anything from Oxitec recently, but the company did indicate it would submit a request for research authorization if it received EPA approval to extend its pilot.

We wouldn’t have a [mosquito] release without major community engagement.” — Judith Pierce, Alameda County Mosquito Abatement District

All research requests are rigorously reviewed by the state for safety to people and the environment, Bailey said. The value or necessity of the data generated by the research is also considered and communicated to the public, she said. Detailed information on authorizations are passed to affected county agricultural commissioners, she said.

As for “Friendly” mosquitoes: “DPR is evaluating how to incorporate public input into its review process should Oxitec submit an RA request. DPR will also work with the California Department of Public Health and Mosquito and Vector Control Districts to inform the process,” she said. 

“It is really hard to say how long the state approval process will take,” said Yarbrough, the state mosquito association spokesperson. “Before a pilot project is initiated, there will be discussions by the mosquito district that decides to partner with Oxitec.”

With the regulatory role of local control districts still an apparent gray area, Castillo said if the issue ever comes here (based on the presence of Aedes aegypti), “It will be reviewed and discussed by our board at a publicly noticed meeting.” 

Said Pierce: “We wouldn’t have a [mosquito] release without major community engagement.” 

Perls stressed the need for public education and input. 

“Given how little communication there is with the public, and lack of public participation opportunities with the state’s decision, it’s critical that potentially impacted community members raise concerns now, ahead of a decision,” she said.

Discussion at the Berkeley City Council meeting didn’t attempt to decide the safety or scientific viability of the approach. The council unanimously said it needed more information before taking a stand. Bartlett was thanked by his colleagues for bringing it forward. Several council members, as well as public speakers, stressed the need to review the issue in the context of the city’s Precautionary Principle ordinance, a commitment to decision making that prioritizes the health and safety of people and the environment. 

Pierce said information Bartlett presented to the City Council had other errors, such as claims the altered Aedes aegypti could disrupt the local food chain. She points out that since the mosquito is invasive to the Bay Area, it’s not part of the food chain. 

Pierce and Perls agree that Oxitec should be more forthcoming about which counties are in the running. 

Meanwhile, in Sao Paulo, Brazil, Oxitec is now distributing “Friendly” mosquito hatching boxes for home use. Just add water.

Freelancer Catherine "Kate" Rauch has been contributing to Berkeleyside for several years. Her work as a journalist has encompassed everything from 10 years as a daily news reporter for the East Bay Times,...