LCQ6: Mosquito prevention and control work
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Question:
As the average temperature and rainfall in April this year were higher than those in the same period last year, creating favourable conditions for mosquito growth and breeding, the rise in gravidtrap indexes occurred earlier this year. Regarding mosquito prevention and control work, will the Government inform this Council:
(1) since the Food and Environmental Hygiene Department (FEHD) lowered in August last year the threshold for initiating the strengthened mosquito control work from an area gravidtrap index of 20 per cent to an index between 10 per cent and 20 per cent, of the number of areas where actions have been triggered to date and the frequency thereof, and whether it will consider further lowering the initiating threshold; if so, of the details; if not, the reasons for that;
(2) given that the FEHD's goal is to test by early next year at the latest the application of the "mosquito‑against‑mosquito" approach which makes use of Wolbachia-carrying male mosquitoes for prevention and control of Aedes albopictus, of the respective locations, scales and timetables of the such field trials, and the measures in place to monitor the actual impacts on the number of target mosquito species; and
(3) as it is learnt that some Mainland provinces and municipalities have introduced new technologies for purely physical mosquito control by means of simulating human breathing and body temperature, whether the Government will consider conducting local trials of the aforesaid technologies; if so, of the details; if not, the reasons for that?
Reply:
President,
The Government attaches great importance to mosquito control in order to safeguard environmental hygiene and protect public health. The interdepartmental Pest Control Steering Committee (PCSC), chaired by the Environment and Ecology Bureau (EEB), has been monitoring the gravidtrap index, setting the overall direction of Government's mosquito control work, and promoting targeted mosquito control measures jointly undertaken by departments, the community, private organisations and Care Teams. In view of the rainy season and the associated risk of mosquito-borne diseases, the EEB convened a PCSC meeting in March this year to provide steer to the strengthening of mosquito control work across departments, and met with trade representatives in April this year to appeal for their active participation in mosquito control work.
Regarding the questions from the Hon Yang Wing-kit, our reply is as follows:
(1) The Food and Environmental Hygiene Department (FEHD) places gravidtraps in different areas across Hong Kong to continuously monitor the activity of Aedes albopictus, and publishes the Area Gravidtrap Indices (AGI), so that different sectors can grasp the mosquito infestation situation and take timely control measures accordingly.
To step up mosquito prevention and control, since August last year, the FEHD has advanced the threshold for strengthened mosquito control work, which was originally initiated when the AGI of an area has reached 20 per cent (Level 3), to 10 per cent (Level 2). Between August last year and May this year, the AGI recorded 10 per cent or above for 128 times, covering 52 monitoring areas. Under the enhanced mechanism, the FEHD convened special meetings of the inter-departmental task forces on anti-mosquito work (Task Forces) to co-ordinate departments and stakeholders in strengthening mosquito control, conduct risk assessments, and identify locations with more serious mosquito infestation for targeted action. The FEHD will also notify residential estates that have subscribed to the gravidtrap Rapid Alert System, advising property management agents and residents to take mosquito control measures.
Given the recent rise in gravidtrap indices, the FEHD has strengthened mosquito control work across all districts, including those with indices below 10 per cent. District Environmental Hygiene Offices will convene monthly Task Forces meetings until the indices drop significantly. From January to May this year, the FEHD conducted over 290 000 inspections, initiated 79 prosecutions and issued 159 statutory notices requiring the removal of stagnant water or containers. In addition, the FEHD has placed more than 3 000 new mosquito trapping devices across the territory, which can simultaneously suppress larval growth and eliminate adult mosquitoes, and recommended that other government departments adopt the devices at their venues. As of early June this year, the FEHD, in collaboration with the Education Bureau, has installed over 980 new mosquito trapping devices in primary and secondary schools and special schools. The FEHD has also collaborated with the Development Bureau to issue the "Guidelines on Mosquito Prevention in Construction Sites" to construction sites and relevant personnel through the Construction Industry Council, reminding the practitioners to strengthen mosquito prevention and personal protection.
Taking into account that mosquito control work has already been strengthened across districts this year, and the effectiveness of resource deployment at different levels, the Government has no plan at this stage to further lower the threshold for strengthened mosquito control work (i.e. gravidtrap index reaching at least 10 per cent). The FEHD will closely monitor the mosquito infestation situation and the effectiveness of control measures in each district, and dynamically assess the need to adjust the activation threshold.
(2) The theory of "mosquito‑against‑mosquito" involves female Aedes albopictus mating with male mosquitoes artificially infected with Wolbachia, which would result in laying of eggs that will not survive or hatch. In this regard, releasing such male mosquitoes at specific locations should help gradually reduce the local Aedes albopictus population. As male mosquitoes do not bite humans, they do not increase the risk of mosquito-borne disease transmission. The World Health Organization, having reviewed studies worldwide, stated that Wolbachia had significant public health value in combating dengue fever. Singapore and Guangdong Province have also applied this technology for mosquito control.
The FEHD has commissioned a biotechnology company to conduct laboratory tests for ensuring that Wolbachia-carrying male mosquitoes do not carry pathogens and that their offspring have no survival capability. Only upon confirmation of safety and effectiveness will the FEHD prepare for field trials. As wild Aedes albopictus may also naturally carry Wolbachia, the company must conduct baseline studies to collect data on seasonal changes in mosquito numbers and natural Wolbachia infection rates, for comparison with the conditions after releasing Wolbachia-carrying male mosquitoes, so as to evaluate the effectiveness.
Upon completion of the abovementioned laboratory tests and baseline studies, and after consulting the relevant District Council, the FEHD will determine the site, scale and timetable for field trials. Subject to the work progress, the target is to conduct field trials in early next year.
(3) The FEHD has been actively introducing suitable new technologies and products to enhance mosquito control effectiveness. Regarding the mosquito control technology mentioned in the question, the FEHD has conducted preliminary study of its principle and will procure the device for field trials to assess its effectiveness and feasibility of application in Hong Kong.
Separately, the FEHD is conducting field trials of another mosquito trapping device imported from the Mainland. This device uses special attractants and ultraviolet light to capture adult mosquitoes, and employs artificial intelligence recognition technology to automatically identify mosquito species and numbers, generating statistical data to assist the FEHD in devising more targeted control measures. The FEHD will assess its suitability for application in Hong Kong based on trial results.
Other mosquito control technologies currently applied by the FEHD include:
Mosquito control robotic dogs
Given that it is difficult for frontline staff to conduct fogging operations in densely vegetated areas, the FEHD has introduced a remotely operated robotic dog equipped with an ultra-low volume sprayer. A trial conducted at Tsing Yi Nature Trail in December last year yielded satisfactory results, and the technology is now applied at suitable locations across districts.
Drones
The FEHD deploys drones to survey complex terrain and densely vegetated areas. Through high‑resolution photographs, stagnant water and concealed mosquito breeding sites can be accurately identified, significantly reducing inspection time and manpower requirements.
Electric stairlift
To reduce physical strain and injury risks for frontline staff, the FEHD has introduced electric stairlift to transport fogging equipment and tools at suitable sites across districts.
Effective mosquito control requires joint efforts across departments, sectors and the community. The Government will continue to work closely with relevant departments, stakeholders and the community, and closely monitor the latest developments in mosquito control technologies, introduce suitable new technologies, in order to strengthen mosquito control work on multiple fronts.
Thank you, President.
Ends/Wednesday, June 17, 2026
Issued at HKT 15:10
Issued at HKT 15:10
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