An Interesting Biological Control of Mosquito

ScienceTopping | Sept 8, 2023

Mosquito Mating

Male mosquitoes infected with Wolbachia bacteria are released from laboratory to mate with wild female mosquitoes. Sometimes, mosquito mating can be as short as 15 seconds! Note that their mating position is back-to-back.

IMAGE BY MAKAMUKI0/PIXABAY

With the recent spike in Dengue fever cases in Southeast Asia countries, mosquitoes are again confirmed as the number-one enemy to humans among insects. There are various methods of keeping mosquitoes at bay, including biological control, chemical control, environmental control as well as personal protective measures. Biological control should be the relatively less familiar one among all four methods. Public should have been familiar with the application of insecticides, fogging, drain clearing, mosquito net and mosquito repellants. All these belong to the rest of the four.

When it comes to biological control, biological concepts and ecosystem are the pillar of the control. The first is the use of biological agent — fish. This concept adheres to the law of food chain, whereby predators feed on their preys. Fish feeds on the larvae of mosquitoes in water based on the fact that adult female mosquitoes lay their eggs in water. The reduction of larvae of mosquitoes thus decreases the number of mosquitoes. Therefore, it is recommended for people to have fish in pond if they have a natural pond in their houses. Another must-know biological control is the use of Bacillus thuringiensis israelensis (Bti), a naturally occurring bacterium found in soil. The usage comes in a few forms such as tablets and sprays. Bacillus thuringiensis israelensis produces a toxin that kills mosquito larvae and adult mosquitoes.

The most interesting yet effective one is yet to come. The technique involves vast coverage of biology knowledge.

Wolbachia bacterium is an interesting species that is present in 60% of the insects in the world. For this extraordinary biological control agent to work perfectly, it is effective only if certain species group that is to be reduced in population does not naturally carry Wolbachia. A well-known mosquito species that does not carry Wolbachia naturally is Aedes aegypti.

With the prerequisite checked, the introduction of Wolbachia to this mosquito species that do not naturally have it will cause the eggs laid to be inviable. Notwithstanding, it is important to note that this biological control has nothing to do with genetic modification, unlike transgenic mosquito. First and foremost, Wolbachia bacteria are introduced into the eggs of Aedes aegypti mosquitoes. As the life cycle progresses, the morphed adult mosquitoes now have the bacteria. Male mosquitoes with Wolbachia are then sorted out for use. Since male mosquitoes feed on nectar but not blood, the release of infected mosquitoes later will not aggrevate the disease outbreak. Those infected male mosquitoes are then released to freely breed with wild adult female Aedes aegypti that are not infected with Wolbachia bacteria. Upon mating, the eggs produced will not hatch due to cytoplasmic incompatibility. All in all, the ultimate goal of reducing mosquito population can be achieved, in turn decreasing the mosquito disease outbreak.

Currently, Dengvaxia is the one and only vaccine available worldwide to prevent Dengue infection. However, it is crucial to bear in mind that Dengvaxia is only indicated for those aged between 9 and 45 who have confirmed previous Dengue infections. Therefore, it is sensible to clarify that there is no vaccine for those who have no previous Dengue infection, so the four major means of mosquito control, namely biological control, chemical control, environmental control as well as personal protective measures, must be strictly put in practice to protect citizens from all around the world.

More Awesome Toppings

Coming Up

Discover ABO Blood Group

Digest More