As Biodiversity Dwindles, Mosquitos Turn to Human Blood

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WWhich hat female mosquitoes choose to feed on impacts human health because they transmit pathogens from one host to another. In theory, mosquitoes can feed on blood on any vertebrate, but in practice they may favor certain hosts based on their odor, body heat, or simply availability.

A new study published in Frontiers of ecology and evolution shows that mosquitoes on the east coast of Brazil draw blood from humans more often than from any other animal.

Researchers from the Federal Rural University of Rio de Janeiro in Brazil and the Instituto Oswaldo Cruz examined the diet of mosquitoes inhabiting the Atlantic rainforest. What was once intact forest has been increasingly colonized by human activities, such that only about a third remains wild. As humans drive other vertebrate animals out of their habitat, mosquitoes may need to revamp their diet.

Using light traps for two consecutive days, the researchers captured nine species of female mosquitoes. Of the 1,714 individuals captured, 145 were engorged with blood from recent feedings. The researchers sequenced DNA from the blood in their stomachs and, using a reference database of vertebrate DNA barcodes, were able to identify the sources of the blood meals of 24 mosquitoes. These sources included 18 humans, one amphibian, six birds, a dog and a mouse. Some mosquitoes had blood from more than one diet in their intestines.

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In numbers, humans were the preferred meal source. “With fewer natural options available, mosquitoes are forced to seek out new, alternative blood sources. They end up feeding more on humans out of convenience, as we are the most common host in these areas,” study author and microbiologist Sergio Machado hypothesized in a statement.

Unfortunately for us, mosquitoes are known to easily adapt to the different food sources present in their environment.

With more than 700,000 people dying each year from illnesses caused by mosquito-borne pathogens, mosquito diet is a major concern, according to the study authors. They recommend that mosquito control strategies take into account their demonstrated dietary preferences as part of the risk equation. Continued deforestation of the Atlantic Forest will likely continue to shape mosquito feeding behavior, as “loss of native vegetation is associated with increased transmission of arbovirus causative agents (dengue, Zika, Chikungunya, and yellow fever),” the researchers wrote.

In other words, more people, relative to other animals, are moving the cafeteria from mosquitoes to humans.

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Main image: Loomo Digital / Shutterstock

• Devin Reese

  Published on January 15, 2026

  Devin Reese is the editor-in-chief of Natural history and a science writer based in Alexandria, Virginia.