Disease-carrying mosquitoes now feed mostly on humans

Researchers in Brazil found that mosquitoes in the Brazilian Atlantic Forest are now more likely to feed on humans due to biodiversity loss.  

The Atlantic Forest hosts many vertebrate species. However, only about a third of its original area remains intact due to human activities. As these habitats shrink and wildlife declines, mosquitoes that previously fed on various hosts may bite humans more frequently, increasing the risk of diseases, such as yellow fever, dengue, Zika fever, Mayaro, Brazilian haemorrhagic fever and chikungunya.   

Scientists from Fiocruz and the Federal University of Rio de Janeiro (UFRJ) captured 1,714 mosquitoes from 52 species at two natural reserves using light traps. In the lab, they separated 145 recently fed female mosquitoes and extracted DNA from their blood to identify the vertebrate they had bitten, targeting species-specific genes that serve as an identification “barcode”.   

Of the analysed mosquitoes, blood-meal sources were identified for 24: 18 fed on humans, and the rest on amphibians, birds, canids and mice. Mixed-blood meals, such as a mosquito feeding on both amphibian and human blood, were also described.   

“This [research] is crucial because… a preference for humans significantly enhances the risk of pathogen transmission,” stated Sergio Machado from UFRJ, one of the main authors of the studies published in Frontiers in Ecology and Evolution.   

Identifying human-feeding patterns in mosquitoes can aid in targeted surveillance, prevention and control strategies for disease-carrying mosquitoes.