- [Narrator] Mosquitoes can be annoying,
but how far would we go to stop them?
Some researchers are genetically modifying one
especially pesky species of mosquito
in an attempt to reduce its numbers.
The Aedes aegypti mosquito spreads
some serious diseases.
- Pathogens that can affect humans,
like Dengue virus, Zika virus,
yellow fever, Chikungunya.
You can just simply spray insecticide
and hopefully kill the mosquitoes that way.
The problem with insecticides are
they not only target mosquitoes,
but they also target beneficial insects
like honeybees and butterflies, and things like that.
And then there's numerous examples of Aedes aegypti
and mosquitoes evolving resistance rapidly to insecticides.
So the insecticides are no longer as effective
as they used to be.
So we need new solutions.
Why not use the mosquitoes to control themselves?
- [Narrator] For the first time, genetically modified
male mosquitoes have been released in the US,
created by a biotech pharma called Oxitec.
- It's only the female Aedes aegypti which actually
bite people and which can transmit diseases.
So the males that we release that carry these genes
cannot bite anyone and they cannot transmit any disease.
- [Narrator] These male mosquitoes carry something
called a self-limiting gene.
- It's passed on to all of their offspring
and all of their female offspring that inherit
that gene will die at really early
larval stages of development.
- [Narrator] In other words, when a genetically modified
male mates with a female mosquito,
then all their eggs should inherit the self-limiting gene
and as a result, the female mosquito larvae won't survive.
- Only the females will die and the males will survive.
So the next generation, the males are then gonna go mate
with wild females again, and continue the cycles.
- [Narrator] The goal is that as generations go on
more and more females die, leaving mostly male mosquitoes,
which again, don't bite people.
And since males don't produce eggs.
- We start to see that the overall size
of that mosquito population actually
diminishes pretty rapidly.
- And the goal is that if you release enough of these males,
then eventually, potentially, you might hit a point
where there is no more females left
and you can get eradication of the population.
They haven't demonstrated that yet, but you know,
they do show that you get population suppression.
- [Narrator] This method's already been employed
in other places around the world.
For instance, a four-year program in Piracicaba, Brazil
targeted an area with about 60,000 residents.
- It's been used safely in Brazil for many years.
We have seen that we can reduce the population
of these invasive species, and in the United States,
it's been through very stringent regulatory process.
- [Narrator] Oxitec not only had to get the approval
from the US Food and Drug Administration
and the US Environmental Protection Agency, but they also
worked with Florida state regulators and agencies.
But what about concerns that these
genetically modified mosquitoes will
impact the local ecosystem?
- The Aedes aegypti mosquito is invasive in the Americas
and in the Florida Keys, it makes up less than
four percent of all of the mosquitoes that are actually
present in that ecosystem.
There's no animal that actually depends on it for food
and it's not carrying out any other
vital ecosystem functions.
It's really just there biting people
and sometimes spreading disease.
- They're everywhere.
I mean, I find them in my backyard.
It's a consequence of global warming.
You know, the environment is getting warmer
so their habitable range is expanding.
As this mosquito establishes itself
and spreads throughout more northern states
in the United States and becomes more prevalent,
it's possible that we might start seeing
more Dengue transmission.
- [Narrator] Getting rid of mosquitoes,
even if it is just one species, may seem like a good idea.
But as bioethicist Alta Charo notes, there might be some
risks whenever genetically modified species
are released into the wild.
- Where is this experiment being done?
Who are the people who might be harmed in some way?
And are they the same people who are going to be getting
the benefits or do the benefits flow to somebody else?
The more that there's a disconnect between benefit and risk,
the more you have a problem.
We have been modifying things for all of human history.
Every time farmers tried to cross one plant with another,
what they were doing was trying to modify genetics.
They were doing it inefficiently,
they were doing it with a lot of guesswork,
and they were doing it in a way that might
or might not have an outcome you like.
So it's not as if manipulating genetics is something new.
It's simply that we now have more powerful tools.
They make it more precise, but they also give us
more things we can do.
And it's really about our ability to take advantage
of that power without losing control of the power.
You build in a requirement for some kind of control
and mitigation measure.
We can slow it, stop it, reverse it, mitigate the effects
which makes it possible to take more chances
and get the benefit but reduce the risks.
- [Narrator] Oxitec says they have strong support
within the Florida Keys with 31 out of 33 precincts
in the county voting for the project in 2016.
The results of this project may ultimately
help address concerns about releasing
genetically modified organisms into the wild.
- I think one misconception is that people think, you know,
if you're removing a mosquito, you removing all mosquitoes.
In my opinion, I think it's more ethical
to remove it if you can than to let it continue
to transmit these pathogens that are, you know,
that are very deadly.
(soft tango music)