BIOENGINEERED MOSQUITOES
Winnipeg lab fights disease carriers
In the unofficial mosquito capital of Canada, most people do whatever they can to avoid the clouds of biting, whining pests. Steve Whyard, on the other hand, is creating mosquitoes by the thousands.
Inside his Winnipeg lab, the University of Manitoba biologist is soaking larvae of one of the insect’s most dangerous strains in a special solution to “silence” two of the bugs’ genes.
The result is an army of sterile males with potential to infiltrate and decimate whole populations of mosquitoes.
That’s good news for the battle against summer insects. And, more significantly, could finally give humans the upper hand on illnesses that kill hundreds of thousands annually. But the experiment also launches Canada into a controversial new field — bioengineering — that critics fear might also wreak havoc on humans.
A British company’s proposal to release millions of its genetically modified insects into a Florida Keys community in the near future has stirred up vocal opposition, with 150,000 residents signing a petition to oppose the project.
“They are going to use my kids, my neighbours and my community as a guinea pig,” says Mila de Mier, the Key West realtor who launched the petition. “I’m not a scientist, but I do have common sense. How many times in nature do you get unintended consequences?”
Many scientists do not share de Mier’s worries of inadvertent environmental calamity, and Whyard says his technique avoids the GM controversy entirely. But some kind of disruptive technology would seem called for to counter what remains the world’s deadliest animal.
Despite significant progress over the last decade, the malaria delivered by anopheles mosquitoes is still to blame for 600,000 deaths a year, predominantly among young children and pregnant women. Dengue fever spread by the Aedes aegypti species — the one targeted by Britain’s Oxitec and Whyard — kills 25,000 people annually and sickens up to 100 million more, with cases soaring 30-fold in the last five decades.
Canadians are vulnerable to those and other mosquito-borne diseases when they travel — and to West Nile virus at home.
The tools that have curbed malaria so far — insecticide-soaked bed nets, drug treatment and rapid diagnostic tests — are unlikely to bring more dramatic gains, says Fil Randazzo, deputy director of translational science at the Bill and Melinda Gates Foundation.
And until the foundation’s goal of malaria eradication is achieved, the spectre of the disease rebounding to previous levels remains a distinct possibility, he said.
Vaccines and a one-dose treatment are among the next generation of weapons against malaria, but no magic bullets. Vaccines are also being developed for dengue, though none have shown more than about 50 per cent efficacy.
Meanwhile, reports of resistance to commonly used insecticides are growing.
Taking the battle against such diseases to the next level, say many experts, requires attacking the pathogens’ distribution networks — that minority of mosquito species that spreads illness.
“If you really want to suppress the populations, you either need a technology like (GM), or you’re going to be spraying a hell of a lot of pesticides, which we know is not a solution,” says Murray Isman, an entomologist at the University of British Columbia.
The so-called sterile-insect technique — releasing a fifth column of infertile bugs into the wild population to mate and at least slow down reproduction — has been used for several years, mostly for farm pests. But the traditional sterilizing method of irradiation leaves males weakened in the competition for mates.
That’s where genetic modification comes in. So in addition to its many other projects, the Gates Foundation has invested $60 million into mosquito “precision genetic techniques” that it believes is promising, if still experimental.
“What genetic technology has done is, rather than using a sledge hammer to sterilize mosquitoes, it’s just targeting one gene in the organism,” said Randazzo.