They are small like a small buzz. It doesn’t seem like they can do much damage. But they are deadly. They are carriers of important infectious diseases such as malaria or yellow fever. There are thousands of different types. Most only bite animals. Why do some mosquitoes prefer humans? It turns out there is an answer to that too.
Study the enemy
Scientists have been studying these insects for decades. Occasionally, they want to eradicate populations through genetic engineering. The goal is to end disease carriers. There is a connection between the spread of mosquitoes and the concentration of humans. However, we had no conclusive evidence to support this.
Princeton University researchers worked in sub-Saharan Africa to find out. They collected eggs from one of the most harmful types: Aedes aegypti. It is responsible for zika, dengue or yellow fever. Your conclusions are in the magazine Current biology.
There are two subspecies of this type. One that people prefer. The other about animals. Most insect populations are a genetic mix of the two. The researchers collected eggs that left mosquitoes in the water. Then they incubated them and quantified their behavior. You had the choice between a human and an animal host.
Princeton University geneticist Noah. H. Rose (co-author of the study) tries to explain it. “Mosquitoes preferred animals in most places. In a few places, they chose people. We create a model using environment variables to explain this variation. The intensity of the dry season was the best environmental predictor. However, the density of human hosts in one area also explained some behavioral differences, ”he says.
The conclusions were clear. Mosquitoes that came from dense areas preferred people. If these regions also had a dry climate, the probability would have increased considerably.
Promoting their behavior
“Humans create a good habitat for mosquito larvae. We store water in tanks for later use. Our garbage can also serve as a habitat.”
It seemed clear why some mosquitoes prefer humans. There was something else. Mosquitoes that people liked were genetically different. This indicates that this differentiation took place in a specific place and then spread across Africa.
“Mosquitoes have evolved to specialize in hosts and human habitats. It was the answer to the growing human rule over the territory, ”explains Rose.
The results could have an impact on public health. The results suggest that the rapid urbanization of sub-Saharan Africa will increase the concentration of “man-eating” mosquitoes. “The rapid growth of large cities in Africa represents a major ecological change. Nature is responding to this new threat,” explains Rose. However, our actions also make a difference. If the population has access to clean water and a good home, we can avoid this. “
Our ecological footprint has a decisive impact. Also in the viability of mosquitoes. A lot depends on our actions. Even the containment of viruses spread by these insects is small, but terrifying.