Mosquitoes have earned the title of being the deadliest animal in the world, but just because of a bad apples like humans doesn’t mean that all mosquitoes are out to get you. A team of researchers out of Princeton just spent three years working with a network of local collaborators to learn more about mosquito preferences. Their findings indicate that out of the thousands of species of mosquitoes, only a few chose humans, and even within those species, many mosquitos have other preferences based on location.
The study involved collecting eggs of the Aedes aegypti mosquitoes out of sub-Saharan Africa. This species is most responsible for carrying Zika, yellow fever, and dengue. Of the two subspecies of this mosquito, one prefers humans while the other prefers animals. When the eggs were hatched, the researchers subjected them to the scents of humans and rodents. What they discovered was that the mosquitoes attracted to humans tended to come from areas with a dry climate and a larger human population, which led to the mosquitoes being bred in water provided by humans. “There has been quite a bit of speculation in the literature that the original reason this species evolved to be a human specialist had to do with its use of human water. It’s easy to come up with hypotheses, but what was incredibly surprising was that you could actually see evidence for that,” explains Lindy McBride, one of the authors of the study and a neuroscientist. The study also showed that areas that had a rainy season followed by a long dry season with high heat also preferred humans.
The paper’s major focus was on the evolutionary history of the people-loving mosquitoes, and the data pointed to these species having a single origin. But while the paper’s focus was on history, it holds relevance for the future. Combining the study’s results with climate and population data from the United Nations points to an increase in human-hunting mosquitoes in sub-Saharan Africa by 2050 caused by urbanization. That will also mean a bump in disease transmission. Just remember, though, that it’s not all mosquitoes—just the ones that have been bred to like human blood.