In Parliament on 3 Feb 2026, I raised concerns about mosquito biting reports I received from several Hougang residents following the local release of mosquitoes under Project Wolbachia. One resident even showed me the bites on her daughter and samples of mosquitoes she had collected to prove the extent of the problem. While it is my understanding that male mosquitoes do not bite, the evidence from my constituents could not be ignored.
The Minister for Sustainability and the Environment explained that the sorting process is 99.9% accurate and that no reports of bites from male Wolbachia mosquitoes have been received. It is likely that any bites come from existing local female mosquitoes or the tiny fraction of female Wolbachia mosquitoes that occasionally slip through the sorting system.
It is reassuring to know that this technology remains a safe and powerful tool that has already slashed dengue risk by over 70% in some areas. I fully support these innovative efforts to keep our community safe from disease and I will continue to work with the authorities to address any feedback from the ground.
This is the full question and answer:
Error Rate In Sex-Sorting Process For Mosquitoes In Project Wolbachia And Process To Ensure These Mosquitoes Lack Physiological Capability To Bite Humans
Mr Gerald Giam Yean Song asked the Minister for Sustainability and the Environment (a) how many reports of biting by male Wolbachia mosquitoes have been received since 2024; (b) what is the current error rate for the sex-sorting process for Project Wolbachia; and (c) what scientific evidence ensures that these released male mosquitoes lack the physiological capability to bite or draw blood from humans.
Ms Grace Fu Hai Yien: We have not received any report of biting by male Wolbachia mosquitoes. Residents in Project Wolbachia sites may still experience mosquito bites from female mosquitoes of species that are found locally, including those not released by Project Wolbachia. Source reduction efforts, therefore, remain important in suppressing the mosquito population.
Through our rigorous laboratory studies and quality control checks, we found that the sex-sorting process for Project Wolbachia achieved an accuracy of 99.9% The small number of female Wolbachia mosquitoes inadvertently released is negligible compared to the overall mosquito population in the community, and these females have significantly reduced ability to transmit diseases. Neighbourhoods where male Wolbachia mosquitoes have been released have seen an 80% reduction in female Aedes aegypti mosquito populations and more than 70% reduction in dengue risk.
NEA has thoroughly studied the Wolbachia-Aedes suppression technology and conducted independent risk assessments, concluding that it is safe and poses no risk to human health. This conclusion is supported by international research and independent reviews.
Source: Singapore Parliament Reports (Hansard)