Small Forest Patches in Costa Rica Found to Curb Disease-Carrying Mosquitoes and Support Biodiversity.

A recent study led by Stanford University has uncovered a surprising link between tree conservation and public health in Costa Rica. Published in Landscape Ecology, the research shows that small areas of tree cover not only bolster local biodiversity but also limit the spread of invasive mosquitoes known to transmit dengue fever, a potentially deadly illness.

Dengue fever, which can begin with flu-like symptoms and escalate to severe health complications, is primarily spread by invasive species like Aedes albopictus. This mosquito has become more common in many tropical regions, including Costa Rica. However, the study found that areas with more tree cover had significantly lower occurrences of this mosquito, while hosting a greater diversity of native mosquito species.

Johannah Farner, a Stanford Ph.D. student in biology and the study’s lead author, emphasized the ecological benefits of preserving even small patches of trees. “We already knew these habitats were valuable for a wide range of wildlife. It turns out that this also applies to mosquitoes, and in a beneficial way,” she noted. “The native species, which don’t spread disease, help crowd out the dangerous ones.”

Using both satellite imagery and field data collected across forests, farms, and residential zones in southern Costa Rica, researchers found that biodiversity increased with tree cover. This increased competition among species makes it more difficult for invasive mosquitoes to gain a foothold, since there are fewer open breeding grounds and limited resources. Environments with higher species diversity also tend to be more stable and less susceptible to invasions.

The study highlights distinct differences among land types. Forested areas had a wide array of mosquito species—but not the dengue-spreading Aedes albopictus. In contrast, residential areas showed low biodiversity and a higher presence of the invasive mosquito. Agricultural areas fell somewhere in the middle, depending on the intensity and type of land use.

While the findings are specific to Costa Rica, they could inform conservation and land management strategies in other tropical regions where natural habitats border human development. According to senior author Erin Mordecai, associate professor of biology at Stanford, tree protection may offer a dual benefit: conserving ecological systems and lowering disease risks.

“This study shows that natural tree cover can act as a buffer against disease vectors,” Mordecai said. “But it’s also clear that further research is needed to understand the full range of factors driving dengue transmission in rural areas.”

To expand on this work, Mordecai and colleague Giulio De Leo launched the Disease Ecology in a Changing World (DECO) program at Stanford. DECO researchers are now focused on identifying how environmental changes influence disease patterns, aiming to develop more effective interventions for rural communities facing ecological degradation and rising disease threats.

Source:https://phys.org/news/2025-05-small-scale-tree-costa-rica.html

This is non-financial/medical advice and made using AI so could be wrong.