Mosquitoes are biting humans more as wildlife fades, study from Brazil finds

A Brazilian study finds mosquitoes in fragmented Atlantic Forest habitats are feeding more on humans as wildlife declines, raising concerns that mosquito-borne diseases may become harder to control

Mosquitoes may be biting people more often than before, and changes in the environment led by humans themselves could be driving this shift.

 

A new study titled Aspects of the blood meal of mosquitoes (Diptera: Culicidae) during the crepuscular period in Atlantic Forest remnants of the state of Rio de Janeiro, Brazil, published in the journal Frontiers in Ecology and Evolution, finds that mosquitoes in forest fragments showed a clear tendency to feed on human blood. Researchers say biodiversity loss and growing human presence in these areas are likely reducing mosquitoes’ access to animal hosts, pushing them towards humans, a trend with important implications for mosquito-borne disease risk.

 

 

Over several months, researchers used light traps to capture mosquitoes from the forest areas. In total, 1,714 mosquitoes representing 52 species were collected. Female mosquitoes, which are the ones that bite, were separated and examined for traces of blood.

 

Using DNA sequencing techniques, the team analysed blood meals from engorged mosquitoes to identify which animals, or humans, they had fed on. In total, DNA traces from 18 different humans were detected. Birds were the second most common source, while amphibians, rodents and a canid appeared only rarely.

 

The researchers concluded that mosquitoes in these forest remnants showed a “clear tendency” to feed on humans, even though the Atlantic Forest is known for its rich animal biodiversity.

Why are mosquitoes turning to humans?

The study points to habitat loss as a major driver. Large parts of the Atlantic Forest have been cleared for agriculture, housing and other human activities. As wildlife populations decline, mosquitoes lose their traditional blood sources.

 

With fewer animals available, humans, now more numerous and more present in these areas, become the most convenient option.

Does this mean mosquitoes prefer humans?

According to the study, mosquitoes are highly adaptable and respond to cues like carbon dioxide, body heat, and odours. When humans dominate a landscape, mosquitoes learn quickly that we are reliable hosts.

 

The study suggests this growing reliance on human blood is less about innate preference and more about environmental pressure and opportunity.

Why does this matter for public health?

Mosquitoes are major carriers of diseases such as dengue, Zika, malaria, and yellow fever. When mosquitoes feed more often on humans, the chances of disease transmission increase.

 

The study highlights that as we alter natural ecosystems, mosquitoes adapt, and not in ways that benefit us.  For more health updates, follow #HealthWithBS