Genetically modified mosquitoes let loose in some parts of the world to combat dengue fever (common in India) have raised both concern and excitement at the ongoing global conference on biodiversity here.

As delegates hotly debate the topic of living modified organisms (LMOs), GeneWatch UK, a not-for-profit group monitoring developments in genetic technologies globally, is worried over the reported open releases of UK biotech company Oxitec’s genetically modified (GM) mosquitoes in Brazil to reduce transmission of dengue fever.

“Billions of Oxitec’s GM mosquitoes are expected to be released in Brazil in attempts to suppress the wild population of mosquitoes. To date, Brazil has not consulted neighbouring countries on releases of these living modified mosquitoes,” the group said in a paper circulated at the conference.

The UN meet is discussing issues related to the safe transfer, handling and use of LMOs, which are products of modern biotechnology. These include decisions to advance the implementation of the 10-year strategic plan for the Cartagena Protocol on Biosafety.

Oxitec hopes that GM mosquitoes can reduce populations of disease-carrying mosquitoes by 80 per cent, even while civil society groups have questioned the overall safety of deploying genetically modified insects to counter spread of diseases.

GeneWatch claims that production of Oxitec’s GM mosquitoes was being scaled up to 2.5 million transgenic mosquitoes a week for open releases in Brazil. “Preliminary results from open release experiments in Brazil show that a release ratio of 54 GM mosquitoes to one wild-type male was used in the final phase of the experiments,” the report points out.

It says that although only a small percentage of the GM mosquito offspring (about 3-4 per cent) are expected to survive to adulthood, this could mean very large numbers. “If ten million GM mosquitoes are released a month, 30 to 40 thousand could survive and half of these will be GM females which bite humans,” it said.

“To date, Brazil has not published any information on the Biosafety Clearing House about its open release of 10 million GM mosquitoes since February 2011,” it adds.