Mosquitoes are impossible to avoid in Texas, despite the best of precautions I don’t think there are many who can say they go a whole summer bite-free. Yet for all your itching, bug-spray buying, and complaining about these pests, how much do you actually know about mosquitos? In this blog, I will be covering some basic mosquito science to explain their life cycle, how they bite, why it itches, and how researchers plan to reduce their impact on the spread of diseases, such as Zika.
There are nearly 3,000 species of mosquito, which by the way comes form the Spanish meaning “little fly,” a name that belies their true nature. As most of us know, mosquitoes lay their eggs in water, preferring stagnant pools, which is why one of the best ways to combat their populations is to educate the public to eliminate possible breeding grounds in their own back gardens.
As stated in a previous article, a mosquito can lay eggs in as little as a teaspoon of water so this vigilance cannot be overstated. These eggs hatch into larva, become pupa (both of which are water-dwelling) and only become flies when they reach adulthood, they leaving their birthplace in search of two things – a mate and a meal.
Adult female mosquitoes can live anywhere from a few days to several months, depending on the species and conditions. Males generally don’t last a week and are actually not guilty of that bite you may be scratching while reading this. Only females have the long proboscis, or mouth, that is required to penetrate skin and feed; the males tend to live on plant nectar. This difference is attributed to the fact that the females need more protein in order to lay eggs – a direct correlation has been observed between egg laying and blood meals for the female, which suggests she needs blood to perform this most basic of biological functions.
So what happens when the female mosquito does bite? Recent research has shown that the mouth can actually bend almost at right angles as it enters your skin, so it can search for the best blood vessel on offer. As she bites, the mosquito is also injecting you with some of her saliva. This saliva contains anticoagulants, which are a type of protein that stops your blood from clotting. This is essential as, without them, your blood would clot very quickly and she would not be able to feed. It is these proteins that actually cause the characteristic mosquito bite itch.
After the bite is done (whether by her choice or your swift hand), some saliva will remain under the skin and the itch is part of the body’s immune response to this foreign compound. The itch will remain until your body has broken down the protein.
We are also now learning that the saliva may be key to why mosquitoes are so efficient at spreading diseases. Scientific studies have shown that a mammal is more likely to catch a virus that is injected by a mosquito as opposed to a needle and, not only that, but the virus will likely affect that mammal far more.
So what can SCIENCE do to prevent the spread of disease from mosquitoes? One of the most promising avenues of scientific research is focused on genetic alteration of the mosquito. This is a complicated idea because, for example, scientific ethics cannot easily justify the release of any female mosquitoes that could go on to breed and produce offspring that could spread disease, even if they are helpful in the long run.
One idea (already underway) is to produce and then release male mosquitoes that will pass on a trait to any offspring, which results in their failure to reach adulthood. Over time this could lead to a significant reduction in the population. Another project is attempting to identify the gene that determines whether a mosquito becomes male or female. The goal of this research is to activate the male DNA, so that any mosquito produced is male, which would also cease reproduction and the spread of disease.
If these studies are successful, then their impact would be felt far outside of the Texas borders, as mosquito borne diseases are prevalent the world over. Hopefully, sometime soon, science will tame the bite!