Written by: euronews
Published in
A scientific study showed that the shrinkage of the Atlantic forest in Brazil is causing mosquitoes to change their feeding behavior and increasingly turn to feeding on human blood, as it is the most easily available host after the decline of wild animals.
The researchers warned that this shift raises the risk of transmission of dangerous diseases such as yellow fever, dengue fever, and Zika, stressing that understanding mosquito behavior has become necessary to enhance health surveillance and develop effective preventive strategies that take into account environmental balance.
The Atlantic Forest is one of the most diverse ecosystems in the world, hosting birds, amphibians, reptiles, mammals and fish found nowhere else. However, urban expansion has left only about a third of its original area, which has forced many animals to disappear or retreat.
A recent study published in the journal Frontiers in Ecology and Evolution suggests that mosquitoes living in the remains of these forests compensate for the lack of natural blood sources by feeding increasingly on humans, as they are the “easiest host to find.”
“Here we show that the mosquito species we captured in Atlantic Forest remnants have a clear preference for feeding on humans,” said the study’s lead researcher, Dr. Jerónimo Alencar, a biologist at the Osvaldo Cruz Institute in Rio de Janeiro.
Co-researcher Dr. Sergio Machado, a specialist in microbiology and immunology at the Federal University of Rio de Janeiro, added, “This is extremely important, because human preference for an environment rich in vertebrate diversity significantly increases the risk of transmission of pathogens.”
Man is at the forefront
To find out where the blood mosquitoes actually feed on, the research team set up light traps in two protected areas in Rio de Janeiro state, then analyzed samples from female mosquitoes filled with blood. After extracting DNA from the blood, the researchers identified the source of the meals by matching genetic sequences to a reference database.
The team collected 1,714 mosquitoes from 52 different species, including 145 females that fed on blood. They were able to identify the source of 24 blood meals, most of which were human: 18 from humans, along with one from amphibians, six from birds, one from canids, and one from a mouse. It has also been shown that some mosquitoes feed on more than one host.
The researchers attributed this preference to several factors, including the availability and proximity of the host. “Mosquito behavior is complex,” Alencar said. “Even if some species have innate preferences, host availability and accessibility are crucial factors.”
Risk of disease transmission
As deforestation continues and humans move into previously forested areas, mosquitoes’ habits and habitats are changing and they are moving closer to human populations. “Natural options are dwindling, so mosquitoes are forced to look for alternative sources of blood, with humans often being the most common choice,” Machado explained.
The effects of bites are not limited to itching, as mosquitoes in the study areas transmit dangerous viruses such as yellow fever, dengue fever, Zika, mayaro, sapia and chikungunya, which pose a serious threat to public health and may have long-term effects.
The researchers pointed out that the decrease in the percentage of blood-filled mosquitoes, as well as the difficulty of determining the source of some meals, highlights the need for broader and more accurate studies, using techniques capable of detecting mixed meals.
However, the study confirms that it contributes to developing more effective policies to combat disease-carrying mosquitoes and predict future outbreaks of epidemics. “Knowing that mosquitoes in an area prefer humans is an early warning of the risk of disease transmission,” Machado said.
Alencar concluded by saying: “This allows targeted control and prevention measures, and may lead in the long term to control strategies that take into account environmental balance.”
