There was a buzz around Braddell Heights yesterday morning, with a group of people clad mainly in white polo T-shirts out at Jalan Riang playground to welcome the newcomers to the estate.
"Normally, I would welcome new residents. Today, I welcome a different kind of resident... the male Wolbachia-carrying Aedes aegypti mosquito," said the area's MP, Mr Seah Kian Peng, drawing laughter from the crowd.
The MP for Marine Parade GRC welcomed about 3,000 of these "residents" - male Aedes aegypti mosquitoes released into the Braddell Heights estate yesterday by the National Environment Agency (NEA) in a pioneering field study to understand the behaviour of the disease-transmitting mosquito species.
The male mosquitoes, which neither bite humans nor transmit disease, have been artificially infected with Wolbachia bacteria. When they mate with uninfected females, the resulting eggs will not hatch.
Traps have been placed in public locations and residential premises around the estate to try to recapture the mosquitoes and determine where and how far they fly from the point of release in Jalan Sukachita.
Mr Seah said it was a privilege for Braddell Heights to be part of this study. When he learnt of NEA's plans, he asked the team to "please come to Braddell Heights first".
Behind this adventurous initiative is a team of more than 30 at NEA's Environmental Health Institute (EHI), who plan to release mosquitoes at two more sites: Tampines West on Oct 28 and Nee Soon East on Nov 15.
Regular releases will be made at the three sites over the next six months to accumulate data on the mosquitoes' flight patterns. The data will go into mathematical modelling, helping the researchers design a subsequent study of how effectively Wolbachia can suppress the mosquito population in the field.
If these studies are successful, NEA hopes Wolbachia technology will eventually complement its existing mosquito control efforts.
NEA and grassroots leaders have been visiting residents, throwing block parties and conducting other outreach activities to raise awareness of Wolbachia technology.
EHI director Ng Lee Ching thanked residents who have volunteered to keep fan traps at home to capture mosquitoes, so as to track their movements. "The people who host the fan (traps) are one of our most important partners," he said.
Retiree Tan Soo Kon, 78, who has lived in Jalan Girang for 30 years, sees this as a breakthrough initiative worth supporting. He said his fan trap had caught 10 mosquitoes the night before the Wolbachia-carrying mosquitoes were released, adding: "I hope some of these (Wolbachia-carrying) mosquitoes will fly to my house and make it safer."
Associate Professor Vernon Lee, a member of the Dengue Expert Advisory Panel appointed by NEA in 2014, said the field study is essential for understanding the effectiveness of Wolbachia technology in Singapore. He added that the panel is satisfied that the study is safe, given prior risk assessments by NEA.
Dr Raman Velayudhan, coordinator of vector ecology and management at the World Health Organisation's Neglected Tropical Diseases Department, said: "We hope this trial will produce a long- term sustainable solution for the control of Aedes mosquitoes... Innovative control measures are absolutely essential for the future."
While the study is in progress, residents should continue normal mosquito control measures like the five- step Mozzie Wipeout, said NEA.