3,000 bacteria-carrying mosquitoes released at Braddell Heights

Angela Lim Channel NewsAsia 18 Oct 16;

SINGAPORE: The National Environment Agency (NEA) on Tuesday (Oct 18) began its six-month trial in using bacteria-carrying mosquitoes to tackle the mosquito population in Singapore.

The agency released 3,000 male Wolbachia-carrying Aedes aegypti mosquitoes at Braddell Heights on Tuesday as part of a six-month field study to learn more about the species. This will also be done at Nee Soon East and Tampines West next month.

Over the next six months, an average of one to three male mosquitoes per person will be released weekly at multiple points in Tampines West, and monthly from a single point in Nee Soon East and Braddell Heights.

They will not be released directly into homes, but instead at stairwells, void decks and other open spaces, NEA said.

While the male mosquitoes may fly around and enter homes to seek out females and find shelter, they will not bite or transmit disease. Eggs produced from the male Wolbachia-carrying Aedes aegypti mosquito and a female urban Aedes aegypti mosquito will not hatch.

The study aims to find out if mosquitoes behave in the same way in the urban environment as they do in the laboratory. This will be done by studying how far and high they fly, how long they live, and how well they compete in the urban environment.

Dr Ng Lee Ching, who heads the study, said: "The key important data we're collecting is flight range. So we only release at one point and we have traps all over in the community.

"We're very happy to have residents to host fan-traps, and they'll be collecting data for us," she added.

The study will run till March next year, according to NEA.

- CNA/kk

3,000 infected mosquitoes released in Braddell Heights under NEA’s population study
Today Online 18 Oct 16;

SINGAPORE — About 3,000 male Wolbachia-carrying Aedes aegypti mosquitoes were released in Braddell Heights on Tuesday (Oct 18), kicking off the second phase of a study to curb disease-bearing mosquito population.

The National Environment Agency (NEA) said this is the first batch of mosquitoes infected with the naturally-occuring Wolbachia bacteria to be released under a small-scale study in three locations. 

The Braddell Heights area (see below) comprises predominantly landed homes in and around Jalan Riang and Jalan Sukachita. There are 216 houses in this cluster. 

The first release of the mosquitoes in the other two locations — Tampines West and Nee Soon East (see locations below) — will commence Oct 28 and Nov 15 respectively. 
One to three mosquitoes per person will be released regularly at public spaces – such as stairwells and void decks – around each of the three housing estates as part of the study which will last six months.

Currently, releases are planned for every four weeks at a single point at Braddell Heights and Nee Soon East, and weekly at multiple points at Tampines West.

The study will allow NEA to move towards using these infected male mosquitoes to suppress the population of the dengue-transmitting Aedes aegypti mosquitoes in the community. As male mosquitoes do not bite, the mosquitoes released in the trial will not transmit any diseases.

“This field release today is critical to help us understand its effectiveness in the Singapore context, through close monitoring of the trial results. The results will help to calibrate the strategy for maximal mosquito suppression and reduction of dengue in Singapore,” said Dengue Expert Advisory Panel member, Assoc Professor Vernon Lee of the National University of Singapore’s Saw Swee Hock School of Public Health.

The NEA also said a comprehensive risk assessment of Wolbachia technology has been undertaken, which has determined it to be safe, with no risk to human health and insignificant risk to ecology. 
The majority of residents at the selected sites are supportive of the study, said NEA, which added that it had conducted more than 100 engagement sessions with stakeholders and members of the community to generate awareness and understanding of the Wolbachia-Aedes technology.

Wolbachia study: What you need to know
Today Online 18 Oct 16;

SINGAPORE — The National Environment Agency (NEA) on Tuesday (Oct 18) kicked off the second phase of a study into how Wolbachia-carrying Aedes aegypti mosquitoes can help curb disease-bearing the mosquito population. It released about 3,000 male Wolbachia-carrying Aedes aegypti mosquitoes in Braddell Heights on Tuesday.

Here are some information on the study, which will span six months.

What is Wolbachia?

Wolbachia is a naturally-occurring bacteria found in over 60 per cent of insect species, but not in the dengue-carrying Aedes aegypti mosquito. Wolbachia has not been shown to infect humans or other mammals, even when carried by biting insects.

How does this study work?

The local Aedes aegypti mosquito does not carry Wolbachia naturally. The National Environment Agency’s Environmental Health Institute managed to rear Aedes aegypti mosquitoes carrying the Wolbachia in their laboratories, and will be releasing only the male Wolbachia-carrying mosquitoes to mate with female Aedes mosquitoes.

Eggs produced from their mating will not hatch because they are biologically incompatible.

Over time, it is hoped that this will reduce and suppress the Aedes aegypti mosquito population, as well as the potential spread of diseases such as dengue.

Why these three sites?

The NEA said they were selected because:

- They represent a cross-section of typical housing estates in Singapore;

- They have seen dengue outbreaks previously and/or have Aedes aegypti mosquitoes present in the environment;

- The NEA has been monitoring the mosquito population in these sites for up to three years, so there is a baseline from which to make comparative studies.

Where else?

Countries that have tested Wolbachia technology similar to what NEA is using include the United States, Thailand and China.

Australia, Vietnam and Indonesia have tested a different type of Wolbachia technology to replace the Aedes population to block the transmission of diseases, though its impact on dengue has not been proven.

The other approach involves releasing both male and female Wolbachia-carrying Aedes aegypti mosquitoes. As Wolbachia is passed on from the female Wolbachia-carrying Aedes aegypti mosquitoes to their offspring, this method is used to rear subsequent generations of Wolbachia-carrying Aedes aegypti.

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