New Delhi: A recent study from Brazil has found that deforestation and biodiversity loss may be altering mosquito feeding behaviour, prompting these insects to increasingly target humans over other wildlife. The research, conducted in the Atlantic Forest, underscores how environmental changes can have direct public health implications by heightening the risk of vector-borne diseases.

Biodiversity Loss in the Atlantic Forest

The Atlantic Forest, stretching along Brazil’s eastern coast and extending into Paraguay and Argentina, is a global biodiversity hotspot. It hosts thousands of plant and animal species, many of them unique to the region. However, decades of human expansion, deforestation, and urbanisation have reduced the forest to roughly 30 percent of its original size, researchers from Brazil’s Federal University of Rio de Janeiro and the Oswaldo Cruz Institute said.

This fragmentation of habitat is not only threatening wildlife but also changing the ecological behaviour of disease vectors like mosquitoes. As natural hosts become scarcer due to human encroachment, mosquitoes are reportedly turning to humans as a primary blood source.

The Study: Mosquito Feeding Patterns

The study, published in the journal Frontiers in Ecology and Evolution, involved capturing 1,714 mosquitoes from two natural reserves in Rio de Janeiro: Sítio Recanto Preservar and the Guapiacu River Ecological Reserve. These mosquitoes represented 52 species, but only 145 females were engorged with blood and suitable for analysis.

Laboratory testing identified the blood sources of 24 of the 145 engorged females. The results revealed:

• 18 blood meals from humans
• 6 from birds
• 1 from an amphibian
• 1 from a canid
• 1 from a mouse

The study concluded that mosquitoes in this biodiversity-rich environment were increasingly feeding on humans, a significant shift from their previous wide range of natural hosts.

Implications for Public Health

Co-author Sergio Machado, a researcher in microbiology and immunology at the Federal University of Rio de Janeiro, explained that this behavioural change has serious consequences. “In an environment like the Atlantic Forest with great diversity of vertebrate hosts, a preference for humans significantly enhances the risk of pathogen transmission,” he said.

The researchers attribute this shift primarily to deforestation and human expansion, which reduce the availability of natural hosts and push mosquitoes into closer contact with people. “With fewer natural options available, mosquitoes are forced to seek alternative blood sources. Humans end up being the most convenient and prevalent hosts in these areas,” Machado said.

This pattern increases the likelihood of diseases such as dengue, Zika, and chikungunya spreading in communities near forested areas, as mosquitoes that historically fed on wildlife begin targeting humans.

Ecological Insights and Future Strategies

The study highlights how human activity directly influences mosquito ecology and, by extension, the dynamics of disease transmission. Understanding mosquito feeding behaviour is therefore crucial for developing effective vector control strategies and public health policies.

Researchers hope that such findings can inform preventive measures, including:

• Targeted mosquito control in regions bordering shrinking forests
• Monitoring disease vectors in areas undergoing rapid urbanisation
• Protecting remaining wildlife habitats to maintain natural feeding patterns of mosquitoes

The study also serves as a wake-up call for conservation, showing that loss of biodiversity is not only an environmental concern but also a public health issue. By conserving natural habitats and maintaining ecological balance, humans may reduce their exposure to zoonotic and vector-borne diseases.

Conclusion

The research from Brazil’s Atlantic Forest provides clear evidence that shrinking forests and wildlife loss are altering mosquito behaviour, with a marked preference for human blood. This phenomenon underscores the interconnectedness of ecological health and human health. Policymakers and scientists are urged to incorporate ecological considerations into disease prevention strategies to prevent outbreaks of mosquito-borne illnesses in areas impacted by deforestation.

The study emphasizes that protecting biodiversity is not only about saving species but also safeguarding human health, as the natural balance between humans and disease vectors becomes increasingly disrupted.