Babyless future for dengue mozzies?

SINGAPORE - Mess with us, and we may even make you sterile. This seems to be Singapore's message to the dengue-spreading mosquito as the Republic considers using biological weaponry to tame the problem.

Since last year, the Environmental Health Institute (EHI) has been carrying out laboratory studies on using Wolbachia, a naturally occurring bacteria, to help suppress the breeding of Aedes aegypti mosquitoes.

This method of biological control involves using Wolbachia-carrying male Aedes aegypti mosquitoes to mate with Aedes aegypti females to produce eggs which do not hatch.

So far, lab results seem positive and the National Environment Agency (NEA) has appointed a panel to assess the possibility of taking this a step further.

Speaking to reporters at the launch of the "Do The Mozzie Wipeout" campaign 2014 yesterday, Grace Fu, Second Minister for the Environment and Water Resources, said that Singapore was "not under any pressure" to use this method of dengue control.

"Of course, we want to fight dengue as quickly as we can, but we also want to make sure that the study is thorough and safe," she added.

EHI's studies showed that male Aedes aegypti mosquitoes here which carry the bacteria are "sterile" when they mate with female mosquitoes in the field. They are also able to compete with other males in the wild for mates.

A newly formed panel, made up of six local and foreign experts, will assess the suitability of using this method for dengue control.

The panel will convene in August. It includes experts such as Duane Gubler from the Duke-NUS Graduate Medical School and the head of the Singapore Armed Forces' Biodefence Centre, Vernon Lee.

Another panellist, Timothy Barkham, told My Paper in an e-mail interview that it was still "premature to make strong comments" about the method at this time but it "makes sense to consider all options".

"Working harder at vector control has not solved the problem, so it makes sense to consider all options, including the Wolbachia technology, which uses laboratory-bred mosquitoes to deliver the Wolbachia to wild mosquitoes," said the associate professor at the department of microbiology, National University of Singapore.

"Mosquitoes are much better at finding other mosquitoes than we are. So it sounds attractive to use them in this way."

In April, British scientist Steven Sinkins told My Paper that the bacteria do not affect humans.

"It originates from fruit flies, so even if humans are eating any fruit they are probably eating little bits of Wolbachia from the fruit flies. It doesn't do any harm," he said.

Last year, British company Oxitec successfully conducted a trial in Brazil where male mosquitoes that were genetically modified were released to produce offspring which died before reaching maturity. The mosquito population was brought down by 96 per cent over six months.

Last year saw the highest number of dengue cases on record here, with more than 22,000 cases. As of June 7 this year, about 7,000 cases have been reported.

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