Reports Show Genetically Modified Mosquitoes Ineffective and Risky

GeneWatch UK released an updated report on Oxitec’s releases of genetically modified (GM) mosquitoes in the Cayman Islands. The report cites new information regarding ineffectiveness and risks, including the annual report of the project, recently released as a result of a Freedom of Information request.

The annual report was not available to the National Conservation Council (NCC) at its June 4th meeting, when it approved an island-wide roll-out of GM mosquito releases.

The new information shows that the releases have been ineffective and large numbers of biting female GM mosquitoes have been released.

“Plans to roll-out Oxitec’s GM mosquito releases island-wide must be halted whilst this new information is properly considered”, said Dr Helen Wallace, Director of GeneWatch UK, “Oxitec’s GM  technology is failing in the field and poses unnecessary risks. Islanders’ money should not be thrown away on an approach which has not been successful.”

The new information shows:

  • Oxitec has struggled to suppress the wild population of mosquitoes with its GM releases, and has only had an effect in the dry season, when numbers are low, and when combined with spraying;
  • Oxitec has been criticised for using egg traps to claim its GM mosquito releases have suppressed the local mosquito population, because egg traps do not measure the number of adult females which bite and cause disease. In the annual report, for the first time, adult female numbers are reported, which show that any suppression in adult female numbers is much delayed compared to what is measured by the egg traps, and is preceded by increases (spikes) in adult female numbers associated with the releases;
  • Spikes in adult females which follow the GM releases might be caused by the inadvertent releases of GM females (although other explanations are also possible);
  • Controversially, the project allowed up to 1,000 biting female GM mosquitoes to be released per week, but in practice up to 9,000 biting females were released per week due to a problem with sorting males and females;
  • When the roll-out is scaled up, this could lead to up to 180,000 GM biting females being released per week if the sorting problem is not solved, or 20,000 GM biting females per week even if the sorting criterion is met.

There remains no evidence that the GM mosquito releases reduce the risk of transmission of dengue, zika or chikungunya.

The GeneWatch report has been sent to all members of the Cayman Islands Government.

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