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Human activities promote mosquitoes

Christian Fernsby |
Mosquitoes may be more likely to occupy areas impacted by human activities like pesticide use and habitat destruction, than they are areas less disturbed by humans, a recent Oregon State University study found.


Working in a national park in South Africa, researchers found a significant difference in the abundance and species composition of mosquitoes inside the park versus densely populated areas outside the park, with the species known to spread diseases such as malaria and Zika virus more common in the human-impacted areas outside the park.

"People care a lot about what environment a lion needs to succeed in; we've researched that extensively. But people don't do that with mosquitoes. We don't understand them as a group of species and how their ecology differs between species," said study co-author Dr. Brianna Beechler, a disease ecologist and assistant professor of research in Oregon State University's Carlson College of Veterinary Medicine.

To find disease mitigation strategies for vector-borne diseases, which are diseases that spread via parasites like mosquitoes and ticks, mosquitoes are an obvious target, Beechler said. But scientists don't yet understand mosquitoes well enough to specifically target the species that cause disease.

"All we can do is reduce mosquitoes overall, but what may be more effective is to reduce certain species by modifying their habitats," she said.

To compare how mosquitoes fared inside Kruger National Park versus in densely populated areas, researchers looked at five "pressures" wrought by human presence: organophosphate pesticide abundance; eutrophication, which is the over-mineralization of water that leads to widespread algae growth; population density; ungulate biomass, which includes domestic animals like cattle and wild animals like impala and buffalo; and vegetation loss.

Human populations affect mosquito habitat and breeding patterns in a sort of domino effect. For example, pesticide use spreads into ponds and other small bodies of water, killing the fish and removing the natural predators that would otherwise eat mosquito larvae and keep the insect population low.


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