Ahead of the release of genetically modified mosquitoes in West Bay, scheduled to begin Thursday, the Mosquito Research and Control Unit and U.K. biotech firm Oxitec invited members of the media for an inside look of the new lab, where half a million male Aedes aegypti mosquitoes are being bred.
The tour was an opportunity to learn about the science behind the GM mosquitoes and discuss what MRCU director Bill Petrie described as “dangerous” misinformation about the project.
The project aims to release sterile, non-biting male Aedes aegypti mosquitoes to help fight the species that transmits diseases such as dengue, chikungunya and Zika.
MRCU and Oxitec officials said the public response to the project has been mostly positive, although there are many individuals in the Cayman Islands who have met the project with skepticism and have been lobbying against the planned release.
Mr. Petrie said he has witnessed a lot of false information about the project being shared and discussed online.
“Some of it is conspiracy theories, which are by and large quite ludicrous and ridiculous – but some of them are quite dangerous, because this is a public health issue,” Mr. Petrie said.
One such theory that has been making the rounds online, Mr. Petrie said, is that Zika is not a cause of birth defects.
“That’s reprehensible,” Mr. Petrie said. “The [World Health Organization] have now confirmed – basically the scientific consensus is – that Zika is a cause of microcephaly and other birth defects.”
Mr. Petrie said “some people seem to be insisting” that Zika is not a serious condition, and that the project to release GM mosquitoes is an overreaction. However, Mr. Petrie said that Cayman’s acting medical officer of health, Dr. Samuel Williams-Rodriguez, has “stressed” that while Zika may not be as serious for most individuals as diseases like dengue and chikungunya, “the effects on the unborn child seem to have been forgotten.”
Mr. Petrie said that another misconception about the project is that it “didn’t receive proper approval” and that there is “no legislation is governing this.”
“That’s incorrect,” he said. “The National Conservation law here does cover genetically modified organisms and in order to get our permits to do this project … we had to satisfy the Department of Agriculture, the Department of Environment and the National Conservation Council, as to all the details of the project, and then it was granted approval.”
Inside the lab
The GM mosquitoes are bred in a converted shipping container on the MRCU grounds. A containment area outside the door to the lab ensures that no mosquitoes accidentally come in or out.
Inside the lab, 15 racks – resembling sheet-pan racks one might see in a commercial kitchen – contain 20 trays each, with 10,000 mosquito larvae swimming in each tray. The larvae, fed with fish food, are reared in the water-filled trays for eight days as they grow into pupae.
At the pupal stage, the female Aedes aegypti mosquitoes – which are larger than males – are separated from the males via a metal sieve. The females are frozen overnight to ensure that they are dead before they are discarded.
Oxitec Project Manager Renaud Lacroix said “one female in every 3,000 males might get through” the sieve, and that scientists are constantly improving the separation method and that such numbers were marginal compared with the number of female Aedes aegypti in the wild.
During a release in Panama in 2014, only one in 10,000 females managed to sneak in with the males.
He added that Oxitec’s GM female mosquitoes do not live as long as their wild counterparts – dying after two to four days, as opposed to one to two weeks – making it less likely that a rogue GM mosquito could bite someone with Zika and transmit it to another person, given the incubation time for the disease in a mosquito is eight to 10 days.
The male mosquitoes are reared in the lab for an additional few days until they reach adulthood, at which point they can be released into the environment.
Mr. Lacroix also said the release “comprises 20 times more male [Aedes aegypti] mosquitoes than there are in the wild.”
These male GM mosquitoes contain a “self-limiting gene” that produces a protein that prevents the mosquito from reaching adulthood. When the males are released, they mate with wild female Aedes aegypti mosquitoes, which are the carriers of disease.
Their offspring inherit the “self-limiting gene” and die before reaching adulthood, thereby reducing the wild Aedes aegypti population.
The GM mosquitoes also contain a marker gene that produces a protein that produces a fluorescent light that can viewed under a microscope. Scientists can check how effective their male mosquitoes are at breeding with wild females by taking samples of mosquito eggs, collected from ovitraps, and looking for this fluorescence.
The MRCU plans to release the male mosquitoes later this week somewhere in the project’s 300-acre operational rollout area in West Bay between Watercourse Road, Powell Smith Lane, Rev. Blackman Road and Hell Road. One hundred to 200 “pots,” each containing approximately 1,000 male mosquitoes, will be released three times a week. The “pots,” which are small plastic canisters about six-inches in diameter are released from a truck, through a fan, and disperse rapidly into the environment to seek out their female mates.
Among those helping to breed and release the GM mosquitoes are a team of young Caymanians who have been hired to assist with the project.
Giselle Johnson, a 23-year-old who is studying for a degree in nursing, and Hedia Groves, a 19-year-old who graduated from Cayman Prep and High School last year, are two of the young Caymanians hired as project assistants to help with the breeding and release of the GM mosquitoes.
During the tour, Mr. Lacroix deferred to the young women as they explained aspects of their jobs in the lab, where they help to breed and monitor the breeding rates of the GM mosquitoes.
Ms. Groves said working on the project “has been a great opportunity” that has gotten her interested in pursuing a future career in science.
Ms. Johnson and Ms. Groves also both happen to be residents of West Bay, where the nine-month project will take place.
“Most of the responses we get are positive,” Ms. Johnson said, when asked how their neighbors respond when she describes her new job.
“We just have a few that maybe don’t understand it … What I say to people, because I live in West Bay, I have kids – I would never put my kids in danger just for a project or for money.”