The genetically modified mosquitoes were meant to mate with Aedes aegypti.
The Indonesian government has put on hold its plan to release 200 million genetically modified mosquitoes to combat dengue after opposition from locals. According to South China Morning Post (SCMP), these Aedes aegypti mosquitoes would have carried Wolbachia, a kind of bacteria that prevents viruses like dengue from growing inside them. The lab-bred mosquitoes were meant to be released in dengue fever 'red zones' in the city of Yogyakarta in mid-November, but critics warned that the pilot study is not robust enough to justify the release of the new species.
"We are currently discussing with the Bali Provincial Government to temporarily delay the release of Wolbachia-carrying mosquitoes and conduct further public dissemination until the community is prepared," SCMP quoted Indonesia health ministry spokeswoman Siti Nadia Tarmizi as saying.
Wolbachia is a common bacteria that occurs naturally in 60 per cent of insect species, including some mosquitoes, fruit flies, moths, dragonflies and butterflies. It is not, however, found in dengue-carrying Aedes aegypti mosquitoes.
Non-governmental organisation World Mosquito Program (WMP), which initiated the research, said they planned to produce "good" mosquitoes by allowing those carrying dengue to mate with mosquitoes carrying Wolbachia injected in labs.
The government had planned to launch Yogyakarta programme in Bali, Semarang, Bandung and Jakarta in Java, and Kupang in East Nusa Tenggara.
The SCMP report said that such pilot programme has been rolled out in 12 countries, covering 8.6 million people. According to the Centre for Tropical Medicine at Gajah Mada University, the study, which began in 2011, found "a 77.1 per cent reduction in dengue incidence in Wolbachia-treated communities".
However, critics pointed out the small sample size - of around 4,500 people - in the Indonesian city won't be giving a clear picture if the experiment is successful of not.
"I am not saying this is fraudulent or that there is any corruption here, just that this is based on one pilot study in Yogyakarta," Michael Northcott, professor emeritus of ethics at the University of Edinburgh in Scotland, told SCMP.
"This should not be done in Bali until there has been a large-scale replication in Yogyakarta. Have you seen Jurassic Park? Life evolves spontaneously, and attempts to intervene usually fail," Professor Northcott added.
In addition to health concerns, the programme could also present a number of legal issues, according to Bali-based lawyer Yulius Benyamin Seran.
"From a legal perspective, it is clear that the state is obliged to protect all Indonesian citizens from any potential threats from other countries or foreign institutions. So the state is obliged to carry out in-depth lab tests on these mosquitoes by involving experts in the field to ensure that the mosquitoes are truly safe before being released. In my opinion, the release of mosquitoes must be reviewed, lest it cause a new threat," he said.
According to the World Health Organization (WHO), global dengue infections have risen rapidly in recent decades, with about half of the world's population now at risk. An estimated 100-400 million infections are reported every year.