Tree Type Fuels Mosquito Growth in Poor Areas

Low-income urban neighborhoods in Baltimore and Washington, D.C., are experiencing higher mosquito numbers due to the types of trees present, according to new research. Invasive, non-native plants commonly found in these areas yield leaves that provide a nutrient-rich food source for mosquito larvae. This enhanced diet allows young insects to survive longer, mature faster, and become larger adults, increasing their capacity to spread dangerous viruses.

Historically, disease experts observed a puzzling pattern: wealthier neighborhoods with dense, diverse tree cover had fewer mosquitoes than poorer areas. This disparity is attributed to years of underinvestment, leading to the prevalence of fast-growing, nonnative weeds and trees in underserved communities, while native trees are prioritized in affluent areas. Researchers found a clear link between nonnative leaves and improved insect development, with larvae growing faster and exhibiting higher survival rates.

Furthermore, a diet of nonnative leaves reduced competition between mosquito species, enabling them to coexist. Female Asian tiger mosquitoes, which spread dengue and Zika, also developed longer wings when fed these leaves, indicating larger body size. Larger mosquitoes tend to live longer and bite more frequently, making them more effective disease vectors. This suggests that city planting strategies, by replacing invasive plants with native young trees, could offer substantial public health benefits and help control mosquito populations.