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US to Use Genetically Modified Mosquitoes to Fight Dengue Fever

Aedes aegypti mosquitoes are seen at the Laboratory of Entomology and Ecology of the Dengue Branch of the US Centers for Disease Control and Prevention in San Juan, March 6, 2016. (REUTERS/Alvin Baez)
Aedes aegypti mosquitoes are seen at the Laboratory of Entomology and Ecology of the Dengue Branch of the US Centers for Disease Control and Prevention in San Juan, March 6, 2016. (REUTERS/Alvin Baez)
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US to Use Genetically Modified Mosquitoes to Fight Dengue Fever

Aedes aegypti mosquitoes are seen at the Laboratory of Entomology and Ecology of the Dengue Branch of the US Centers for Disease Control and Prevention in San Juan, March 6, 2016. (REUTERS/Alvin Baez)
Aedes aegypti mosquitoes are seen at the Laboratory of Entomology and Ecology of the Dengue Branch of the US Centers for Disease Control and Prevention in San Juan, March 6, 2016. (REUTERS/Alvin Baez)

After a decade of discussions, officials in Florida have voted to allow the first test in the United States of free-flying, genetically modified mosquitoes that kill any female offspring, as a way to fight the pests and the diseases they spread.

The decision came after about two hours of contentious testimony in a virtual public hearing on August 18. Many speakers railed against uncertainties in releasing genetically engineered organisms. In the end, though, worries about mosquito-borne diseases proved more compelling.

On the day of the vote, dengue fever cases in the Florida Keys islands totaled 47 so far in 2020, the first surge in almost a decade.

The same mosquitoes known for yellow fever (Aedes aegypti) also spread dengue as well as Zika and Chikungunya. The species is especially hard to control among about 45 kinds of mosquitoes that whine around the Keys.

According to a report by the Science News website, the genetically modified mosquitoes plan will kick off in January, 2021. Florida workers will set out boxes of eggs of specially bred male yellow fever mosquitoes. The eggs will grow into normal-looking males, and like other male mosquitoes, they drink flower nectar, not blood.

Then planners hope that during tests, these Oxitec foreigners will charm female mosquitoes into mating. A bit of saboteur genetics from the males will kill any female offspring resulting from the mating, and over time that should shrink the swarms. Sons that inherit their dad's no-daughter genes will go on to shrink the next generation even further.

By now, Oxitec has supplied some billion saboteur male mosquitoes for release elsewhere around the world, especially in Brazil, where Zika can flare up and dengue is common.

The company believes that its successful trials in other regions around the world are a sufficient response to the objections surrounding its project. No potential harms on humans or environment have been observed in the locations where genetically modified mosquitoes were launched.

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Climate Change Causing More Change in Rainfall, Fiercer Typhoons, Scientists Say 

People and vehicles wade through the water along a street that was flooded by Typhoon Gaemi in Kaohsiung on July 25, 2024. (AFP)
People and vehicles wade through the water along a street that was flooded by Typhoon Gaemi in Kaohsiung on July 25, 2024. (AFP)
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Climate Change Causing More Change in Rainfall, Fiercer Typhoons, Scientists Say 

People and vehicles wade through the water along a street that was flooded by Typhoon Gaemi in Kaohsiung on July 25, 2024. (AFP)
People and vehicles wade through the water along a street that was flooded by Typhoon Gaemi in Kaohsiung on July 25, 2024. (AFP)

Climate change is driving changes in rainfall patterns across the world, scientists said in a paper published on Friday, which could also be intensifying typhoons and other tropical storms.

Taiwan, the Philippines and then China were lashed by the year's most powerful typhoon this week, with schools, businesses and financial markets shut as wind speeds surged up to 227 kph (141 mph). On China's eastern coast, hundreds of thousands of people were evacuated ahead of landfall on Thursday.

Stronger tropical storms are part of a wider phenomenon of weather extremes driven by higher temperatures, scientists say.

Researchers led by Zhang Wenxia at the China Academy of Sciences studied historical meteorological data and found about 75% of the world's land area had seen a rise in "precipitation variability" or wider swings between wet and dry weather.

Warming temperatures have enhanced the ability of the atmosphere to hold moisture, which is causing wider fluctuations in rainfall, the researchers said in a paper published by the Science journal.

"(Variability) has increased in most places, including Australia, which means rainier rain periods and drier dry periods," said Steven Sherwood, a scientist at the Climate Change Research Center at the University of New South Wales, who was not involved in the study.

"This is going to increase as global warming continues, enhancing the chances of droughts and/or floods."

FEWER, BUT MORE INTENSE, STORMS

Scientists believe that climate change is also reshaping the behavior of tropical storms, including typhoons, making them less frequent but more powerful.

"I believe higher water vapor in the atmosphere is the ultimate cause of all of these tendencies toward more extreme hydrologic phenomena," Sherwood told Reuters.

Typhoon Gaemi, which first made landfall in Taiwan on Wednesday, was the strongest to hit the island in eight years.

While it is difficult to attribute individual weather events to climate change, models predict that global warming makes typhoons stronger, said Sachie Kanada, a researcher at Japan's Nagoya University.

"In general, warmer sea surface temperature is a favorable condition for tropical cyclone development," she said.

In its "blue paper" on climate change published this month, China said the number of typhoons in the Northwest Pacific and South China Sea had declined significantly since the 1990s, but they were getting stronger.

Taiwan also said in its climate change report published in May that climate change was likely to reduce the overall number of typhoons in the region while making each one more intense.

The decrease in the number of typhoons is due to the uneven pattern of ocean warming, with temperatures rising faster in the western Pacific than the east, said Feng Xiangbo, a tropical cyclone research scientist at the University of Reading.

Water vapor capacity in the lower atmosphere is expected to rise by 7% for each 1 degree Celsius increase in temperatures, with tropical cyclone rainfall in the United States surging by as much as 40% for each single degree rise, he said.