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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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Researchers Warn that Global Warming is Likely to Increase illness among individuals

The study said that increased heat may cause illness through undernourishment in a number of ways

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Global Warming
Global Warming is one of the biggest threats to the reduction of hunger and undernutrition, especially in low and middle-income countries. Pixabay

Global warming is likely to increase illnesses caused by undernutrition, due to the effects of heat exposure, researchers have warned.

For the study published in the journal PLOS Medicine, the researhers analysed daily hospitalisation data covering almost 80 per cent of Brazil between 2000 and 2015.

They studied the link between daily mean temperatures and hospitalisation for undernourishment according to the International Classification of Diseases.

“The association between increased heat and hospitalisation for undernutrition was greatest for individuals aged over 80, and those 5 to 19 years,” said the researchers from Monash University, Australia.

The researchers found that for every 1 degree Celsius increase in daily mean temperature during the hot season, there was a 2.5 per cent increase in the number of hospitalisations for undernutrition.

“We estimated that 15.6 per cent of undernutrition hospitalisations could be attributed to heat exposure during the study period,” said study’s lead author Yuming Guo.

The study said that increased heat may cause illness through undernourishment in a number of ways: reducing appetites, provoking more alcohol consumption, reducing motivation or ability to shop and cook and exacerbate any undernutrition, resulting in hospitalisation.

Global Warming
Global Warming is likely to increase illnesses caused by undernutrition, due to the effects of heat exposure, researchers have warned. Pixabay

“Climate change is one of the biggest threats to the reduction of hunger and undernutrition, especially in low and middle-income countries. It has been estimated that climate change will reduce global food availability by 3.2 per cent and thus cause about 30,000 underweight-related deaths by 2050,” the report said.

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“It is plausible to speculate that climate changes could not only increase the rate of undernutrition in the most affected areas of the globe, but at the same time, impair individuals’ capacity to adapt to projected rises in temperature,” said the researchers. (IANS)