To Bite or Not to Bite: Research Reveals Taste Preferences of Mosquitos for Human Sweat

Many of us have endured mosquito bites. But sometimes, mosquitoes might just land on a person and then fly away. Why do mosquitoes choose to bite some people and not others?

Researchers from Yale University may have found an answer to this question — the key is in how your sweat tastes. “They have this very sophisticated taste system that allows them to taste many different compounds that are present on our skin’s surface, and those compounds influence their decision to bite or fly away,” said Dr. Lisa Baik, a biologist at Yale University and lead author of this study. Their findings were published in Nature.

The study focussed on Aedes albopictus or the Asian tiger mosquito, a species that not only spreads diseases such as dengue and Chikungunya, but has also been expanding its range rapidly. Once found only in its native habitat of South and Southeast Asia, this species has spread to all six continents in the last few decades, outcompeting native mosquitoes in many regions.

The researchers studied individual taste-sensing hair-like structures, called sensilia, present at the tip of the mosquito’s proboscis — the needle-like organ that it uses to pierce through skin. They used a small glass pipette, much like a dropper, to introduce solutions with different tastes to the mosquito’s proboscis. They introduced 46 different tastes to the mosquitoes and noted which ones were attractive. Sugar was a favorite taste, in keeping with mosquitoes’ love for nectar which makes up a significant portion of their diet. However, for female mosquitos, nectar is not enough — they seek blood. That is because blood contains amino acids which are important for the proper development of their eggs.

But how do the mosquitoes know which human blood is most suitable? This is where our sweat comes in. Human sweat contains a mixture of water, salts and amino acids, but individuals vary in the exact composition. Interestingly, the researchers found that some human sweat samples were more likely to induce biting than others. When testing sweat components separately, it was evident that a combination of salt with amino acids induced mosquitoes to bite, and not either of those alone. Higher concentrations of certain amino acids in the solution was likely to cause increased biting. Some humans possibly had more of the amino acids that mosquitoes like on their skin surface, making their sweat tastier, the researchers hypothesized.

Understanding what makes for a tasty mosquito meal is crucial, as their spread threatens our health, globally. “Because of climate change, the range of mosquito borne diseases are spreading at an alarming rate. It really is a big public health problem,” Baik said. As northern latitudes get warmer, more mosquito species are able to adapt to and thrive in these regions. Domestic outbreaks of dengue and Chikungunya have already occurred in many parts of Europe where these diseases were not previously endemic. Closer to home in Florida, dengue outbreaks continue to be a cause for concern, with this species and its close relative, the yellow fever mosquito, being the major vectors.

Baik plans to extend this work to other species of mosquitoes, such as the yellow fever mosquito and the marsh mosquito, which is the primary vector for malaria. By unlocking mosquito tasting mechanisms, she hopes to go beyond identifying compounds that cause them to bite. “Maybe we can identify new kinds of compounds that can prevent mosquitoes from biting”, said Baik. “That would mean that we can slow or even stop the spread of diseases.”