Question: Could we breed a mosquito that doesn't carry diseases?


  1. Great question! Unfortunately, the answer is ‘probably not’, because mosquitoes don’t carry diseases on purpose. The diseases are carried along by accident because they don’t infect the mosquito, and are usually transferred in the blood that the mosquito is drawing.

    On the other hand, scientists working on a disease called dengue fever have done something really clever. Dengue fever is a caused by a virus, and the scientists in the Australian team have managed to infect mosquitoes carrying the virus with a bacteria, Wolbachia, that actually blocks transmission of the virus! It’s a long story, though, so if you want to know more about it I’ll refer you to this really great article by Ed Yong.


  2. that would be great!

    as Steven said, it’s not the mozzies’ fault, they just carry the disease over to us!

    In theory, you could generate a genetically modified mozzie that has a resistance to the bug it is carrying, as in, the mozzie will kill the bug before it can make a human sick. If you create enough of these mutant mozzies and they start breeding with the normal mozzies, over time you could wipe out the nasty bug that makes us sick…

    But, I think humans have often messed around with nature, thinking something was a brilliant idea, only to discover later that it was a disaster! For example the cane toad. Not native to Australia at all, but now totally out of control! So often we can come up with great ideas on paper, but things might be too risky to do….



  1. Actually, Natasha has a good point about resistance. I was thinking of whether we could breed a mosquito that just couldn’t physically pick up disease or transmit it to start with, but reading her answer reminded me of a story I read a couple of months ago about a team from the US and France. One of the interesting things about mosquitos (and other insects, collectively called ‘arthropods’) is that they don’t have what we call an adaptive immune system. In humans, the adaptive immune system helps us fight off diseases that we’ve already had by ‘remembering’ them and produces – among other things – antibodies that help fight off the specific infection.

    Meanwhile, mosquitoes are the main way that humans get a disease called malaria, which is actually caused by a parasite. The parasite (called Plasmodium) is picked up by the mosquito from an infected human, and the Plasmodium then reproduce inside the mosquito before being transmitted to the next uninfected human. Though there are treatments for malaria, it’s not a pleasant disease to have and so we’re always looking for ways to control it.

    That’s where the American / French team comes in. They found a way to put genes into the mosquito that manufacture antibodies – which, remember, mosquitoes normally don’t do – that kill the Plasmodium parasites as they’re maturing in the mosquito or bind them and prevent them from being transmitted. This doesn’t harm the mosquito and they can (theoretically) spread easily in a wild population of mosquitoes, making this a great way to fight malaria.

    Natasha is right to mention the unintended consequences of introducing new variants like this. On the other hand, as the study authors mention, the possibility of a field trial is still a ways off, partly because of the need to satisfy everyone about that exact problem! Also, if you put aside the genetic modification, this isn’t that much different from something called sterile insect technique, where huge numbers of sterile insects (flies, mosquitos, etc.) are released into the wild to interfere with the natural insects. The idea there is to make it difficult for normal insects to find a mate that can actually have children, that isn’t sterile. In several cases, we’ve managed to completely eradicate the targeted pest using this technique, and we’ve been using it since the 1950s, so we have a reasonable idea of how these sorts of programs might work.