While researchers hope to expand their genetically modified mosquito program to the entire island of Grand Cayman around February, a U.K.-based nonprofit organization has released a report questioning the efficacy of the initiative and criticizing the project’s public approval process.
According to GeneWatch UK, which describes itself as a watchdog for how genetic technologies are developed and used, the initiative between Cayman’s Mosquito Research and Control Unit and U.K. company Oxitec to release genetically modified mosquitoes that produce offspring that die before adulthood has been far less successful than the MRCU and Oxitec claim.
The organization also says that Cayman’s National Conservation Council did not consider important data before giving approval in June for the project to be expanded from West Bay to the entire island of Grand Cayman.
The MRCU released a statement in response to GeneWatch but did not address any of the environmental group’s specific claims.
“MRCU and Oxitec are engaged in ongoing discussions regarding the expansion of the ‘Friendly Aedes aegypti program,’” the Mosquito Research and Control Unit stated. “MRCU has followed due process to comply with all regulatory requirements. The program is a public health initiative to combat the Aedes aegypti mosquito, which is an invasive species in the Cayman Islands and the primary vector of viruses, including Zika, dengue, chikungunya and yellow fever.”
National Conservation Council Chairwoman Christine Rose-Smyth said her department would not comment on the matter until all its members have the opportunity to consider the matter.
Though the GM mosquito program did not yield its desired results right after it started in July 2016, by late November the mosquito populations were suppressed when compared to the populations of the control area a few miles east, according to the MRCU’s report on phase one, which was published in June. Suppression levels were determined by comparing the number of eggs and adult mosquitoes caught in the traps laid in the respective areas.
The report states that by March, the amount of eggs per trap in the target area was 35 percent of that in the control area. The adults trapped showed “a similar trend, though of a lower amplitude initially,” the report added.
“This outcome is within expectations according to previous field suppression observed in [the] Cayman Islands, Brazil, and Panama with substantial suppression observed within four to six months following start of releases at an adequate rate,” the report concludes.
The GeneWatch report paints a far different picture. According to that report, while the project did achieve population suppression as measured by comparing eggs per trap, Oxitec and the MRCU had to release far more GM mosquitoes than they originally stated.
GeneWatch said Oxitec initially stated in May 2016 that it would release between 100,000 and 200,000 GM male mosquitoes weekly, and that the population levels of the Aedes aegypti mosquito would fall dramatically a few months later. However, the number of mosquitoes to be released weekly had to be increased to 500,000 to achieve any observable effect, GeneWatch stated.
These claims differ from the MRCU’s report, which stated that the unit initially released 300,000 on July 28, 2016 and continued to release that number weekly until late November, when it bumped the number up to 400,000 per week. “Increase in production from initial rates was in response to the high mosquito population, due to seasonality,” the MRCU stated. From March until now, the number of GM mosquitoes being released has dropped to 250,000, the MRCU added.
GeneWatch also stated that the number of females “spiked” during the monitored period. While the number of females was higher in the target area than in the control area in late 2016 and early 2017, the population reached consistent suppression levels by early May, according to the MRCU.
GeneWatch further stated that the National Conservation Council approved the islandwide rollout of the project on June 15, which was before the MRCU released its results of phase one on June 25.
The council relied on previous risk assessments from Cayman, Malaysia, Brazil and the U.S. But the Cayman risk assessment does not “meet international standards,” the Malaysia and U.S. assessments “have both been withdrawn,” and the Brazil assessment “includes a dissenting opinion from both experts,” according to the GeneWatch report.
Despite the criticism from GeneWatch, Oxitec’s Cayman project manager, Renaud Lacroix, said the plan is to implement the islandwide program by February. Mr. Lacroix said that is the ideal time to start releasing GM mosquitoes because that is when populations are generally the lowest, making it easier to suppress those populations when they grow.
Officials have not responded to inquiries about how much the project will cost government.