Few researchers really know the reasons that lead tiger mosquitoes to favor human blood over that of animals. According to a study carried out in sub-Saharan Africa, two environmental factors are at the origin of this behavior.
We dread mosquito bites when summer rolls around. Yet a surprising phenomenon is that these insects prefer to attack human prey rather than animal targets. A study published in the American scientific journal “Cell“provides some answers to this observation.
Carried out on the mosquito “Aedes albopictus”, more commonly known as tiger mosquito, this scientific work was carried out in 27 countries of sub-Saharan Africa. Some of the traps used have been set near large cities, others in wild areas where mosquitoes rarely encounter humans.
Result of the study: according to the researchers, there are two environmental factors that cause the tiger mosquito to bite the skin of a human being rather than that of an animal: drought and population density. In fact, during the dry season, female mosquitoes more easily find stagnant water or artificial pools to lay their eggs in highly urbanized areas. After hatching and transforming into adults, new females only need to bite nearby humans for food.
A new genetic evolution is to be feared
By rubbing shoulders with humans, this craving for human blood is written into their gene. And the mosquitoes that have become fond of our blood are not confined to sub-Saharan Africa. The same genes have been identified in invasive species in Argentina or Angola.
Professionals claim that “the rapid urbanization currently taking place in Africa will lead to a further evolution of mosquitoes, causing an increase in human bites in many major cities by 2050.” Vector-borne diseases transmitted by the latter (dengue, Zika, chikungunya and yellow fever) will therefore certainly become even more widespread in a few years.
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