As The National Environment Agency (NEA) intensifies its effort to curb mosquito breeding in Singapore over the years, mosquitoes have also been adapting and have begun breeding in more obscure and hard to find places. To seek them out, a new control method is needed and male Wolbachia-carrying Aedes mosquitoes could be just what they are looking for.
After years of studies and risk assessment on various novel control tools at the Environmental Health Institute, NEA has identified and shown the potential of using only male Wolbachia-carrying Aedes aegypti mosquitoes. As it is well known that Aedes aegypti is the primary dengue vector and male mosquitoes do not bite or spread illness to people, male mosquitoes can be used to control the Aedes aegypti population in Singapore.
Wolbachia pipientis is a naturally occurring bacterium found in more than 60% of insect species around us including butterflies, dragonflies, and various mosquito species. However, it is not found in Aedes aegypti. Wolbachia does not harm humans or other animals and is already present in Aedes albopictus and Culex mosquitoes that bite humans and animals.
Aedes aegypti are less likely to transmit dangerous viruses like dengue, Zika, yellow fever or chikungunya when carrying the bacteria Wolbachia pipientis. This is because the bacteria compete with viruses like dengue, Zika, chikungunya and yellow fever and make it harder for viruses to reproduce inside the mosquitoes. Since 2011, scientists have begun injecting Wolbachia into Aedes aegypti mosquito eggs before releasing the developed insects, which pass this defence to their progeny.
A Wolbachia-carrying mosquito is not a genetically modified organism. When a male Wolbachia-Aedes aegypti mates with a female urban Aedes aegypti that does not carry Wolbachia, their eggs do not hatch and there will be no offspring. This form of ‘sterility’ is due to a phenomenon known as Cytoplasmic Incompatibility (CI).
| Matings between urban non-Wolbachia-carrying Aedes aegypti mosquitoes | Non-Wolbachia-carrying female | Non-Wolbachia-carrying male | ➡️ | Produce viable non-Wolbachia-carrying offspring. |
| Matings between urban female and Wolbachia-carrying male Aedes aegypti mosquitoes | Non-Wolbachia-carrying female | Wolbachia-carrying male | ➡️ | Produce eggs that do not hatch. No viable offspring. |
| Matings between Wolbachia-carrying female and non-Wolbachia-carrying male Aedes aegypti mosquitoes | Wolbachia-carrying female | Non-Wolbachia-carrying male | ➡️ | Produce viable Wolbachia-carrying offspring. |
| Matings between Wolbachia-carrying Aedes aegypti mosquitoes | Wolbachia-carrying female | Wolbachia-carrying male | ➡️ | Produce viable Wolbachia-carrying offspring. |
The release of male Wolbachia-Aedes aegypti in the field to compete with urban males for urban females can lead to a reduction in the Aedes aegypti population. The Wolbachia-Aedes technology is an additional resource in Singapore’s dengue control programme. However, no one should let their guard down; it is still essential that each stakeholder does their part to avoid dengue.
What kind of bacteria is Wolbachia?
Wolbachia is an intracellular bacterium genus that mostly infects arthropods, including a large proportion of insects, as well as certain nematodes.
How does Wolbachia stop dengue?
Through two methods, the discharge of Aedes aegypti mosquitoes with Wolbachia could reduce and, in some circumstances, completely eradicate dengue transmission:
- through lowering the number and/or lifetime of mosquitoes
- through lowering mosquitoes’ capacity to spread dengue
How effective is the Wolbachia project?
Male Wolbachia-Aedes mosquitoes released at research sites in Yishun and Tampines, Choa Chu Kang, and Bukit Batok towns decreased Aedes aegypti mosquito numbers by up to 98 percent.
Is Wolbachia a parasite?
It is one of the most widespread parasitic microorganisms and arguably the most frequent reproductive parasite on the planet. Wolbachia has been detected in a variety of arthropod and parasite species across the world, including insects, terrestrial isopods, spiders, mites, and filarial worms.
Is Wolbachia harmful to humans or animals?
Throughout history, Wolbachia has been present in both humans and animals. This occurs when they come into touch with insects, ingest insects, or consume insects-infested foods such as fruit. Yet even with this, Wolbachia hasn’t been linked to any cases of animal or human illness.
How do In2Care Mosquito Stations complement the Wolbachia project in Singapore?
Regardless of whether or not they are carrying Wolbachia, egg-laying Aedes mosquitoes will be attracted to the water with organic odour emitted by the In2Care mosquito stations.
The active ingredients in the In2Care mosquito station contain an approved fungus that kills the mosquito several days after exposure which helps prevent disease transmission. The adult mosquitos visiting the In2Care mosquito station will disseminate larvicide to other breeding places around the vicinity before the fungus takes its toll on them. In this approach, the In2Care mosquito station decreases mosquito populations and continuously maintains them low.
The In2Care Mosquito Station is family-friendly, pet-friendly, does not need power supply and does not produce combustion pollutants. It also has no negative effects on other helpful insects such as bees and butterflies.
Each In2Care mosquito station effectively covers an area of 400 square metres which equals 4300 square feet. The In2Care Mosquito Station offers effective long-term 24/7 mosquito control with reduced need for additional periodic chemical spraying.