This is how they can distinguish humans from animals

Some mosquitoes are only out for humans when looking for food. A new study has analyzed human smell and shown what it triggers in the mosquito brain.

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Towards the summer we are again swarmed by mosquitoes. Most of them drink blood from any creature they can find, others feed on nectar. But some, including the yellow fever mosquito, only target humans. So far it has been unclear how the mosquitoes can distinguish humans from other mammals. Researchers at Princeton University have now identified the responsible odorous substances and in a study demonstrated what these trigger in the mosquito brain.

The team led by biologist Carolyn McBride used genetically modified test animals and state-of-the-art technology to visualize the mosquitoes’ brain activity. The mosquitoes were exposed to various human and animal odors via a wind tunnel. The amazing finding: Only two of the 60 nerve centers in the mosquito brain called glomeruli were activated by smells – one of them specific to humans. The researchers had anticipated a much more complex activity for distinguishing these complicated smells.

Hoping for specific mosquito traps

The smells of humans and other mammals consist of dozens of components and differ in the different proportions of these components. The research team identified two odorants – decanal and undecanal – that are more present in humans, distinguishing them from other mammals. The researchers hope that these substances could now be used to develop odor mixtures for mosquito traps.

Combating yellow fever mosquitoes has long been an important area of ​​research to control disease. It originally comes from Africa, but has spread worldwide in the tropics and subtropics. There it causes problems because it is one of the most important transmitters of dangerous diseases such as yellow, dengue and Zika fever. Transmission occurs when infected female yellow fever mosquitoes feed on human blood to provide nutrients for their offspring. Their male counterparts, on the other hand, feed mainly on nectar.

In addition to conventional methods such as fumigation of residential areas or chemical treatments of water accumulations in which the mosquito larvae are found, genetic engineering experiments were also carried out. More than ten years ago, the British company Oxitec released genetically modified male mosquitoes whose offspring are unable to survive. Although this significantly reduced the mosquito population, years later it turned out that some specimens of the genetically modified mosquitoes were able to reproduce. The consequences of this are unclear.