Genetically modified male mosquitoes may soon be buzzing across areas of
California, in an experiment to stop the spread of invasive species in a
warming climate.
Earlier this month, the
EPA cleared
the UK-based biotech company Oxitec to release a maximum of roughly 2.4bn of
its genetically modified mosquitoes through 2024, expand its existing trial
in Florida and start a new pilot project in California’s Central Valley,
where mosquito numbers are on the rise.
Oxitec’s modified mosquitoes are male, and therefore don’t bite. They were
developed with a special protein so that when they pair with a female
mosquito the only viable offspring they produce are also non-biting males.
The project specifically targets the Aedes aegypti mosquito, one of more
than 3,500 mosquito species and a dangerous invasive insect that has spread
diseases like dengue, Zika, Chikungunya, and yellow fever in other
countries.
The company hopes that releasing its engineered bugs will help control the
Aedes aegypti in California, where numbers have risen in recent years. The
species is already on the move across the state, and has been found in 21
counties according to the California department of public health. The
state’s devastating drought conditions – with low water levels in pipes and
ponds, slowed stagnating streams, and less rain to flush out water systems –
have helped mosquito populations flourish, and they love to lurk near houses
and communities.
The dangerous diseases aren’t yet spreading in California, but the invasive
insect has been highlighted by officials as a growing risk.
“It does not belong here and it is environmentally disruptive,” said Rajeev
Vaidyanathan, irector of US programs at Oxitec, of the Aedes aegypti. He
added that female Aedes aegypti prefer to feed and breed in and around
people’s homes, and are out biting during the day – making them much more
difficult to eradicate with pesticides. “Butterflies and bees are out during
the day,” Vaidyanathan said. “That makes it very incompatible with
traditional mosquito control.”
The company’s so-called “friendly” male mosquitoes are delivered as eggs,
ready to deploy in a “just-add-water” device, which could help curb the high
cost typically associated with eradicating the species.
The project, which will be carried out in partnership with the Delta
Mosquito and Vector Control district in Tulare county, still needs to be
reviewed by California’s department of pesticide regulation. But Oxitec has
already introduced this particular strain of genetically modified mosquitoes
in Brazil and is fresh from a first-year trial in the Florida Keys. The
company claims to have encouraging results. “Every single larva that carried
our gene emerged as an adult male,” Vaidyanathan said. “We didn’t have any
female emergence.”
Oxitec is now eager to test the technology in a new and changing climate.
“There are some fundamental questions we need to answer before we can say
this is a viable tool for mosquito control,” Vaidyanathan said. “How is that
going to affect our boys’ ability to fly? How is it going to affect our
boys’ ability to mate?” he said, noting that the Central Valley is a
“goldilocks” test location due to its arid agricultural landscapes with
temperatures that climb past 100F during the summer. “We cannot extrapolate
with what we have done in Florida.”
The EPA earlier this month concluded that the test was safe to humans and
the environment, but stipulated that the mosquitoes cannot be released near
any potential tetracycline sources, an antibiotic that acts as an antidote.
The regulations include within 500 meters of wastewater treatment
facilities, commercial citrus, apple, pear, nectarine, peach growing areas,
or commercial cattle, poultry and pig livestock producers. All the modified
insects are equipped with a marker gene that scientists can use to tell them
apart from wild ones and regular monitoring will be put in place to ensure
the experiment is going to plan.
Still, the pilot has encountered some resistance. Citing concerns about
possibly unforeseen consequences and a lack of transparency, critics are
calling on California regulators to pull the plug.
“The science was incomplete before the first rollout,” said Dana Perls, the
food and technology program manager with Friends of the Earth of the trial
in Florida. She said California and Florida should not be taking risks with
experimental biotechnology, and said a lack of publicly released data from
the field trials in Florida made it hard to gauge the project’s success.
Close to 13,000 comments were issued to the EPA in opposition to the
project’s expansion this year, the bulk of them signatures collected by the
advocacy organizations Friends of the Earth, the Institute for Responsible
Tech and the Center for Food Safety.
“There’s no such thing as 100% effective in science,” Perls said. “Yet the
public is being asked to trust that Oxitec’s experiment will work and no GE
female mosquitoes will survive. But how do we know that?”
Opponents have also raised questions about the modified mosquitoes’
interaction with Tetracycline, an antibiotic used in agriculture, which can
be found in wastewater and works as an antidote, enabling female mosquitoes
to develop. They fear the complicated interplay could lead to hybrid
mosquitoes that are even more difficult to control. “That’s why there needs
to be transparency. We need unbiased independent review, transparency and
public participation,” Perls said.
Vaidyanathan said the data has been reviewed by regulators and that company
officials had presented findings at conferences across the country. There
are plans to release the data to the public after the regulatory process at
the federal and state level concludes. “We are following the EPA’s strict
guidelines,” he said. “Once we get the permits,” he added, “we can talk
about it publicly.”