In the entire world, there are about 3,500 mosquito species. Out of these, very few have actually started biting humans to eat. This makes them essential vectors when it comes to spreading a lot of diseases. In an effort to predict and to prevent the massive spread of mosquito-borne illnesses, researchers have started to look into why, from an evolutionary point of view, mosquitoes have chosen to bite humans.
Now, in the academic journal Current Biology, in an article published on 23 July, two significant factors have been identified that encourage the human biting of mosquitoes. These are a bustling city life and a dry climate. These results seem to indicate that the increase in urbanization that is predicted to occur over the next decades will lead to more mosquitoes biting humans in the near future.
Aedes aegypti mosquitoes are one of the species that are known to be invasive over all the tropics. They really prefer to attack humans, their habitats, and this makes them very important disease vectors. This statement was made by Carolyn McBride, an affiliate of Princeton University. The researcher continued on, saying that, in their native range in the Sub-Saharan Africa, these mosquitoes exhibit highly variable attraction for human hosts. Some strongly prefer humans, while others strongly go for non-human animals.
Noah Rose, a colleague of McBride, has explained that mosquitoes that live closer to dense human populations, such as in cities near Kumasi, Ghana, or Ouagadougou, in Burkina Faso, exhibited a stronger preference for biting humans instead of non-human animals. This preference is especially strong, however, in places where the dry seasons are intense, such as in the Sahel region, where the little rainfall present is all concentrated during two months a year. The reason for this is probably that mosquitoes living in those climates are highly dependent on humans and the water storage of humans to live and breed.