As part of a trial to control the spread of dengue, male Aedes aegypti mosquitoes carrying Wolbachia bacteria will be released at the Braddell Heights housing estate next Tuesday.

The small-scale trial is the first of three planned by the National Environment Agency (NEA). The other two will be carried out in Nee Soon East and Tampines West within the next month.

When male mosquitoes carrying the naturally occurring Wolbachia mate with females, the bacteria causes the females to produce eggs that do not hatch.

Over time, this could lead to a fall in the Aedes aegypti population; these mosquitoes transmit viruses that cause dengue fever as well as chikungunya and Zika. A trial was first run in Australia five years ago and has shown success in reducing local transmission of dengue.

The authorities here warned earlier that the number of dengue cases this year could exceed 30,000 - higher than the record of 22,170 cases reported in 2013.

NEA said the mosquitoes would be released at regular intervals at each of the three sites. The males do not bite and will not lead to any disease transmission.

The agency has been inviting residents from the three estates to its Environmental Health Institute's mosquito-production facility in Jurong, to learn about the process of rearing these special insects.

Yesterday, about 30 Nee Soon East residents were taken to laboratories there to see what happens up close. In one room, they entered a cage of free-flying male mosquitoes to see for themselves that the males do not bite. Elsewhere, they were shown how male pupae are separated from females.

The six-month field study in the three estates aims to understand the behaviour of Wolbachia-carrying Aedes aegypti in the urban environment - for instance, how far and high they fly, and how well they compete with their counterparts without Wolbachia in mating with females.

To collect data, NEA will be setting up traps at various locations, including public spaces and the homes of volunteer residents. The data gathered will support the planning for a suppression trial, which could start next year.

Residents can contribute to the research by volunteering to host fan-based mosquito traps in their homes and on their premises. NEA will compensate them for the electricity used to power the fan-based devices.