How do mosquitoes develop insecticide resistance?

More and more mosquitoes are becoming resistant to different insecticides and it has become a serious issue nowadays. Mosquitoes are known to transmit many deadly human diseases including Malaria, West Nile virus and Zika virus, and this resistance means that it is much harder to fight against these diseases and the mosquitoes themselves. If mosquitoes are resistant to insecticides, they become almost invincible and that way it becomes impossible to reduce their population and slow down the rate at which they spread the diseases. And only by knowing how mosquitoes develop resistance again insecticides, we can create an action plan and come up with new ways to fight mosquitoes.

Insecticide resistance is caused by genetic changes in an insect. They increase the insect’s ability to prevail over the effects of different chemicals. This means that certain species of mosquitoes are becoming resistant to some insecticide varieties and other substances designed to kill them. And, since these changes are genetic, mosquitoes pass this resistance from one generation to another, which leads to efficacy loss of insecticide over whole colonies of misquotes. Basically, mosquitoes are slowly becoming fully resistant against some insecticides, giving them possibility to survive even large doses of toxic substances that are normally lethal to the pests.

Although people are only now starting to fret about this issue, in reality insecticide resistance is nothing new. It started to develop almost as soon as the first insecticides were manufactured and used for malaria eradication in 1940s. However, nowadays, with how much we are using insecticide on every day basis, it has become a much more common occurrence. And the more we use different types of insecticides, the more immune mosquitoes are becoming against these chemicals. So soon, we might experience a time, when nothing can kill mosquitoes, because they will have developed a resistance against all known insecticides.

insecticide resistanceOne of the main reasons for such a rapid insecticide resistance development is mutations. Mosquitoes overproduce certain enzymes, which cause the enzymes to absorb the insecticide chemicals before they get to the insect’s nervous system and kills them. For example, mosquito species known as Culex pipiens overproduce enzymes A esterase and B esterase, which get the insecticide before it can do any harm to the mosquito. Such overproduction is due to a simultaneous increase in the number of copies of one or two corresponding genes. So basically, the genetics of mosquitoes adapts to the chemicals to a point that the insecticide isn’t harmful to the mosquito anymore. And, because these mutations are spread mostly in certain areas and develop towards certain insecticides, it means that mosquitoes in whole regions can develop insecticide in short amount of time.

The good news is that this problem is finally noticed by experts and scientists and research is being done, to find ways to combat the insecticide resistance and to develop new ways to fight mosquitoes. This research includes steps like entomological observation and data gathering, development of innovative vector-control tools as well as creation of new insecticides that could kill mosquitoes, but that mosquitoes couldn’t develop resistance towards. However, it is not a simple task, as it is hard to find chemicals that wouldn’t cause the genetic mutations in mosquitoes therefore wouldn’t result in insecticide resistance, and that would be safe to humans and other species as well.

So, for now, unfortunately mosquitoes are winning the war against chemicals. Over the past decade, large amounts of money have been spent on developing and distributing new mosquito-fighting chemicals, but without great results. Meanwhile mosquitoes keep developing insecticide resistance against new insecticide types, and we can only hope that scientists will find a way to fight against insecticide resistance soon.


Gregory Martin

So what products have the mosquitoes become resistant to?


    Research shows a widespread resistance to pyrethroids, organochlorines, carbamates and organophosphates.

Samson Banda

A very interesting article indeed!
Does this confirm that evolution is an ongoing process? Many people usually find it hard to accept facts about evolution.


    Depends on what you consider to be an evolution. I wouldn’t go as far as saying forming a resistance alone proves the existence of evolution. But it might be one of the indicators of it for sure.

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