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Global warming may affect pesticide effectiveness

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New Delhi: The effectiveness of an important mosquito-fighting insecticide may be impaired by global warming, according to a recent study.

Two researchers from Montana State University, graduate student Shavonn Whiten and Robert Peterson, have shown that permethrin becomes less effective at killing the yellow fever mosquito (Aedes aegypti) as temperatures increase.

These mosquitoes, which are found in the tropics and the subtropics, can transmit viruses that lead to dengue, chikungunya, yellow fever, and other diseases.

“Many of the areas where these insecticides are employed have varying drastic temperature changes,” Shavonn Whiten said.

The researchers exposed adult mosquitoes to varying concentrations of permethrin at a range of temperatures.

They found an inverse relationship between death and temperature from 16 AoC to 30 AoC, which showed the highest negative correlation.

From 30 to 32, there was, however, a positive correlation between mortality and temperature. And from 32 to 34, the negative correlation resumed.

“It probably has something to do with variability and heat stress,” said Peterson.

“Once you get to those higher temperatures, there are other things going on regarding stress on the mosquito that cancel out the effect of the pyrethroids (a class of pesticides to which permethrin belongs) working better at lower temperatures and worse at higher temperatures,” he explained.

People involved in mosquito-control efforts should take temperature into account when choosing a pest control product, researchers said.

The study was published in the Journal of Medical Entomology.

(IANS)

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Arctic permafrost may unleash carbon within decades: NASA

Plants remove carbon dioxide from the air during photosynthesis, so increased plant growth means less carbon in the atmosphere

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NASA to release two missions focused on moon soon in 2022. Pixabay
NASA positive about next planet-hunting mission. Pixabay
  • Permafrost in Northern Arctic can potentially become a permanent source of Carbon
  • It was previously thought to be safe from the effects of Global Warming
  • Rising temperature in the Arctic can cause severe carbon emissions

Permafrost in the coldest northern Arctic — formerly thought to be at least temporarily shielded from global warming by its extreme environment — could thaw enough to become a permanent source of carbon to the atmosphere in a few decades, warns a NASA-led study. This will happen in this century, with the peak transition occurring in 40 to 60 years, said the study.

Permafrost in Northern Arctic can become a permanent source of carbon in this century itself, according to NASA. Wikimedia Commons
Permafrost in Northern Arctic can become a permanent source of carbon in this century itself, according to NASA. Wikimedia Commons

Permafrost is soil that has remained frozen for years or centuries under topsoil. It contains carbon-rich organic material, such as leaves, that froze without decaying, NASA said in a statement on Tuesday.

As rising Arctic air temperatures cause permafrost to thaw, the organic material decomposes and releases its carbon to the atmosphere in the form of the greenhouse gases carbon dioxide and methane.

The researchers calculated that as thawing continues, by the year 2300, total carbon emissions from the coldest northern Arctic will be 10 times as much as all human-produced fossil fuel emissions in 2016.

Warmer, more southerly permafrost regions will not become a carbon source until the end of the 22nd century, even though they are thawing now, said the study led by scientist Nicholas Parazoo of NASA’s Jet Propulsion Laboratory in Pasadena, California.

That is because other changing Arctic processes will counter the effect of thawing soil in these regions.

The finding that the colder region would transition sooner than the warmer one came as a surprise, according to Parazoo. The researchers used data on soil temperatures in Alaska and Siberia and a numerical model that calculates changes in carbon emissions as plants grow and permafrost thaws in response to climate change.

They assessed when the Arctic will transition to a carbon source instead of the carbon-neutral area it is today — with some processes removing about as much carbon from the atmosphere as other processes emit.

World is under threat due to Global Warming. Wikimedia Commons

They divided the Arctic into two regions of equal size, a colder northern region and a warmer, more southerly belt encircling the northern region. There is far more permafrost in the northern region than in the southern one.

Over the course of the model simulations, northern permafrost lost about five times more carbon per century than southern permafrost.

The southern region transitioned more slowly in the model simulations, Parazoo said, because plant growth increased much faster than expected in the south.

Also Read: Global warming portends ill for India’s flourishing Dairy sector: Experts

Plants remove carbon dioxide from the air during photosynthesis, so increased plant growth means less carbon in the atmosphere.

According to the model, as the southern Arctic grows warmer, increased photosynthesis will balance increased permafrost emissions until the late 2100s. IANS

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