Some years back I surfed the web for the top ten most dangerous animals in the world, you should have seen the expression on my face when I came across the insect “Mosquito” on the top of that list. It does make sense since Mosquitoes account for about a million human death per year.
Female Mosquitoes and Diseases
Surprisingly, only female mosquitoes are interested in human blood, thus transferring diseases that can be lethal if not properly attended to. These diseases range from common yellow fever to the deadly West Nile river.
Her mouthparts are modified to pierce the skin thus sucking the blood out. This will further cause injury and the itchy sensation we feel due to the complex mixture of proteins in the Mosquito’s saliva.
Some enzymes contained in the mosquito’s saliva are responsible for preventing the blood from clotting thus causing the itchy feeling.
Mosquitoes and Human Blood
The more simple answer to this would have been that female mosquitoes work on the principles of vampirism. That’d be cool right but like most arthropods mosquitoes have a liquid clear to a yellowish substance called Hemolymph for blood and as such do not need the human blood for their body to function.
Most arthropods have an Open circulatory system instead of a closed one like humans do with the arteries and veins. What this basically means is that instead of having vessels through which their Hemolymph move the substance just roams all-around freely through the mosquito body sometimes into spaces called Hemocoels.
The female mosquito requires blood to produce eggs, that’s the fundamental answer. Although not all species of female mosquitoes feed on human blood as mosquitoes generally feed on mammals.
Different species of female mosquitoes are attracted to humans for different reasons. Some have evolved to that behaviour due to the scarcity of other mammals or the large population of humans in their habitat. Some due to the unique composition of the human blood.
There are researches that prove certain species are attracted to mammals that give off a certain scent and a certain level of temperature. That could come in handy when trying to explain why mosquitoes need human blood.