Mosquito boss says GM project is safe

(CNS): The release of genetically modified mosquitoes in Grand Cayman poses no threat to people, says the director of the MRCU. A project that is seeking to suppress the stinging dengue carrying pest using male insects which have been genetically altered to be infertile has reduced the mosquito population without using chemicals. The trial has attracted considerable attention because the details of the release seemed to have stayed under the radar. Government did produce a short documentary segment about the project in which the MRCU partnered with the UK firm Oxitec Limited but little information has been circulated in the public domain. Dr Bill Petrie has said people have noting to fear from the trial.

“The males that we release don’t live very long,” he explained to Cayman 27 on Friday. “They don’t persist in the environment so the trans-gene that they possess doesn’t persist in the environment.”

The “mutant mozzies”, as they have been dubbed in some quarters, have attracted worldwide attention and were the first of their kind to ever be released into the wild. Three million of the sterile male mosquitoes, which cannot bite, were released into the local population on the eastern end of the island to mate with females, preventing them from reproducing.

Between May and October scientists released batches of the mosquitoes in cages three times a week in a 16-hectare area. By August, mosquito numbers had fallen by 80 percent, compared with a neighbouring area where no sterile male mosquitoes were released.

In a segment for GIS earlier this year Petrie explained the project was about fighting dengue, for which there is no vaccine or cure and it is on the increase. The mosquito aedes aegyptti associated with the virus populates Grand Cayman but does not carry dengue here. As this mosquito tends to congregate around populated areas scientists are trying to find non-chemical ways of dealing with the dangerous pest. “Any tool we can use against this mosquito would be useful,” he said.

Angela Harris of the MRCU said the technology had gone through years of development in the laboratory and Cayman was at the cutting edge of science by being the first place to test the genetically modified mosquitoes, which should prevent females from reproducing. When females mate with the ‘mutant mozzies’ the resulting larvae always die before hatching.

With this first trial already revealing promising results reducing the levels of the aedes aegypti by an impressive 80 per cent, compared with the untreated site next door, the ‘mutant mozzie’ will now be released where the female mosquito is carrying dengue fever.

Oxitec, which is a spin-out company from Oxford University, is set to carry out five more similar trials around the world over the next year. It had hoped to launch its first dengue fever field trial in Malaysia, but was held up by regulatory problems and criticism from some anti-GM campaigners. Oxitec now hopes the Malaysian trial will start later this month. The delay enabled the Cayman Islands, where aedes aegypti mosquitoes arrived in 2002, to get in first.

Oxitec insists that its GM mosquitoes are environmentally benign and represent the only hope of rolling back the global advance of dengue-infected mosquitoes. Aedes aegypti are an alien species spread by human activity so their eradication would not disrupt local ecosystems.

GIS report on mosquito trial