Human activities increase disease-spreading mosquitoes: Study

A recent study,conducted by a team at Oregon State University, has found out the activity ofdisease-spreading mosquitoes triples in areas which have higher human acitivity.

To conduct the study, the researchers collected samples from inside the South Africa's Kruger National Park and the areas outside the park which are densely populated by humans. The samples showed a vastdifference in the amount of mosquitoes present in the two environments as the samples collected from the areas densely populated had abundance of mosquitoes — that are responsible for spreadingZika and malaria.

“It seems to suggest that disease-carrying mosquito species certainly did better in human-altered environments,” study co-author Dr. Brianna Beechler, a disease ecologist and assistant professor of research at Oregon State University's Carlson College of Veterinary Medicine, said.

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In order to compare the behaviour of mosquitoes in different environments, researchers observed 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."

In 2016-17, during the wet season in South Africa, researchers caught 3,918 female mosquitoes from 39 different species. These mosquitoes were trapped from both inside and outside the national 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,"Beechler said.

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

However, she has stated that the reason behind this is not yet clear, and needs more research.

She has also added that some communities, such as in Carribean, put fish in the standing water which further consume these mosquitoes. However, she also stated that these techniques are not focused on specific disease-transmitting mosquitoes.

Bleacher also explained that these disease-transmiting mosquitoes — especially the ones carrying malaria, zika and chikungunya — have been entering new territories in the past few years, and studies such as these will help ascertain the change in behaviour and pattern of these mosquitoes.

“With climate change, mosquito distributions are likely to change, and disease distributions are likely to change,” Beechler said. “So it’d be nice to know how to target those species before that happens,” she said.