A breakthrough technique harnessing two methods to target disease-carrying mosquitoes was able to effectively eradicate buzzing biters in two test sites in China, according to research published on Thursday.
The mosquitoes targeted are a type that is particularly difficult to control called Aedes albopictus — more popularly known as the Asian tiger mosquito — which are a major vector for diseases including Zika and dengue.
The study “demonstrates the potential of a potent new tool”, wrote Peter Armbruster, a professor at Georgetown University’s department of biology, in a review of the work.
Researchers harnessed two population control methods: the use of radiation — which effectively sterilizes mosquitoes — and a strain of bacteria called Wolbachia that leaves mosquito eggs dead on arrival.
They conducted a two-year trial at two sites on river islands in Guangzhou, where Asian tiger mosquitoes are to blame for the highest dengue transmission rate in China.
The results were “remarkable”, wrote Armbruster: the number of hatched mosquitoes eggs plunged by 94 percent, with not a single viable egg recorded for up to 13 weeks in some cases.
And the average number of female mosquitoes — which transmit disease to humans when they bite — caught by traps fell by between 83 and 94 percent.
In some cases, none were detected at all for up to six weeks.
The results were also borne out by a decline of nearly 97 percent in bites suffered by locals — which in turn shifted attitudes among residents, who were initially sceptical of the project’s plan to release more mosquitoes into the local area.
– Radiation and bacteria –
The research builds on two existing methods: radiation-based sterile insect technique (SIT) and incompatible insect technique (IIT).
SIT works by releasing radiation-sterilized male mosquitoes into an environment to mate with wild female mosquitoes, reducing the size of the population over time as females fail to reproduce.
But irradiation of male mosquitoes tends to reduce both their mating competitiveness and their survival rates, undermining the technique’s effectiveness.
The IIT method involves a bacteria called Wolbachia. When males infected with it mate with female mosquitoes that aren’t infected, their eggs don’t hatch.
The technique doesn’t work if the female mosquitoes are infected with the same Wolbachia strain, and successful mating by mosquitoes that both carry the bacteria undermines the technique by producing more female mosquitoes infected with Wolbachia that are resistant to the process.
Preventing the release of Wolbachia-infected female mosquitoes is difficult, with sex-sorting techniques usually resulting in a “female contamination rate” of about 0.3 percent.
To overcome that, researchers decided to subject their Wolbachia-infected lab-reared mosquitoes to low-level irradiation, which rendered the females sterile but left the males able to reproduce.
This allowed the team to avoid the onerous sex-screening process and meant they could release significantly more mosquitoes at a time: in some cases more than 160,000 male mosquitoes per hectare, per week.
– ‘Striking results’ –
Lead researcher Zhiyong Xi, a professor at Michigan State University’s department of Microbiology and Molecular Genetics, compared the technique to “producing insecticide”.
“Our goal is to use this technique to build a protected area that is disease vector-free,” Xi told AFP.
Armbruster, in a review commissioned by the journal Nature that published the research on Thursday, said the study produced “striking results”.
That the trial “almost eliminated notoriously difficult-to-control vector mosquitoes from the test sites is remarkable,” he wrote.
The results weren’t a universal success — populations in areas with more traffic, near construction or roads, shrank less than those in isolated zones, likely as mosquitoes migrated in from elsewhere.
But Xi said the technique still holds promise if “natural barriers” like highways are used to limit the arrivals of outside mosquitoes.
And he said it could be used against mosquitoes that carry disease, including malaria.
The next steps will involve developing a “highly effective and practical release strategy” suited for urban settings,” he said.
Brazilian President Jair Bolsonaro takes on Norway for whaling, but bungles it
Brazilian President Jair Bolsonaro on Monday responded to Norway's decision to halt its forest protection subsidies, taking to Twitter to criticise the Scandinavian country for its whaling practice and post spectacular -- albeit misleading -- images.
"Look at the killing of whales sponsored by Norway," Bolsonaro wrote on Twitter.
The post includes a video and photographs of a spectacular whale hunt, where mammals in the shallow waters of a bay are slaughtered by people wading on shore, armed with hooked knives. The whales' blood turns the waters red.
However, the images, reportedly taken on May 29 in Norway, illustrate a "grind", a type of pilot whale hunt practised exclusively in the Faroe Islands -- a Danish territory in the North Atlantic.
Orange County teens busted for singing obscure Nazi song while giving Hitler salutes
Nearly a dozen high school students from Southern California delivered Nazi salutes and sang a Nazi marching song in a video posted on social media.
The video was uploaded to Instagram by one member of the boys’ water polo team at Pacifica High School in Garden Grove, California, along with lyrics to the song played for German troops during World War II, reported The Daily Beast.
A spokesperson for the Garden Grove Unified School District told the website administrators learned of the incident in March, four months after the video was posted, but declined to say whether any of the students were disciplined.
History provides us with no shortage of clowns and buffoons who were in politics
“The problem with political jokes,” Groucho Marx once said, “is that they keep getting elected.” Never has that been more true than today. We live in a world ruled by clowns. I mean that both literally and figuratively. Our century has ushered in the Age of the Clown Politician.
In Ukraine, Volodymyr Zelensky, who played a Ukrainian president on the popular television comedy SERVANT OF THE PEOPLE, was elected to be the real president with over 70 percent of the vote. Zelensky is literally a clown. In Great Britain, Boris Johnson, who will replace Theresa May as prime minister, is a buffoon who elicits laughter –usually unintended- wherever he goes. Mr. Johnson is figuratively a clown.