Update on 2016 Pilot Study of Releasing Bacteria-carrying Mosquitoes into Environment

Mr Patrick Tay Teck Guan asked the Minister for the Environment and Water Resources whether he can provide an update on the 2016 pilot study of releasing bacteria-carrying mosquitoes into the environment.

The National Environment Agency (NEA) is evaluating the use of male Wolbachia-carrying Aedes aegypti mosquitoes (Wolbachia-Aedes) to further suppress the Aedes aegypti mosquitoes in the community. Phase 1 field study was conducted at three selected sites at Braddell Heights, Tampines West and Nee Soon East from October 2016 to December 2017. The study had met its objectives and demonstrated that the released male Wolbachia-Aedes mosquitoes had successfully competed with urban male mosquitoes and mated with some female mosquitoes. The releases led to 50% suppression of the urban Aedes aegypti mosquito population at the study sites.

The field study surfaced two challenges posed by Singapore’s high-density and high-rise landscape. First, NEA discovered that mosquitoes moved from surrounding areas into the study sites, thus reducing the impact of Wolbachia-Aedes in the sites. Second, NEA found higher Aedes aegypti mosquito densities at high floors of some blocks, as insufficient numbers of male Wolbachia-Aedes mosquitoes had reached those floors.

To address the high-density and high-rise challenges, NEA is carrying out Phase 2 field study from April 2018 to January 2019. Phase 2 field study will improve the release methodologies to distribute the male Wolbachia-Aedes mosquitoes to where they are needed. NEA will release Wolbachia-Aedes mosquitos at the same Phase 1 study sites at Tampines West and Nee Soon East and their extended areas. Phase 2 field study is an important and necessary step for NEA to refine the release methodologies and address the unique challenges faced due to our urban landscape, in preparation for the subsequent suppression trial.

NEA will continue to engage residents and stakeholders. The cooperation and support from residents and local stakeholders were crucial in ensuring the success of Phase 1 study. Residents and local stakeholders are encouraged to continue supporting NEA in Phase 2 field study. Residents are also encouraged to continue carrying out mosquito control procedures and the five-step Mozzie Wipeout.