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How Perfecting Bug Spray Could Save Millions of Lives

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Thinkstock

Mosquitoes ruin countless American picnics every year, but around the world, the whine of this bloodsucking beast isn’t just irritating—it heralds an epic health problem. More than a million people die from the spread of mosquito-borne diseases like malaria, dengue fever, and yellow fever each year. Attempts to control populations via insecticides like DDT have had ruinous side effects for nature and possibly human health. Neurobiologist Leslie B. Vosshall has a different solution for stopping the insects and the spread of disease. “I believe the key to controlling mosquito behavior is to understand better how they sense us,” she says.

At their Rockefeller University lab, Vosshall and her colleagues are studying the chemical sensory processes by which mosquitoes choose hosts. How do they sense heat, humidity, carbon dioxide, and body odor? What makes some people more attractive to a mosquito than others? It takes blood and sweat to find out. To study how mosquitoes assess body odor, Vosshall and her teammates might wear nylon stockings on their arms and refrain from showering for 24 hours to create sample smells. Then comes the hard part. They insert their limbs into the insects’ den to study how mosquitoes land, bite, and feed and then they document how this changes depending on both the mosquitoes’ genetics and the particular traits of the scientists’ skin. This can mean getting anywhere from one bite to a whopping 400, depending on the experiment. Studying male mosquitoes is more pleasant; since they don’t feed on blood, the lab tests their sense of smell using honey.

Making Mutant Mosquitoes

Vosshall and her team have also begun to study how genetics contribute to mosquitoes’ choice of a host. With a bit of tinkering, she’s even created a breed that is unable to sense carbon dioxide, an important trigger for the insects. “By using genetics to make mutant mosquitoes, we can document exactly how and why this cue acts to make mosquitoes hunt humans,” Vosshall says.

Once Vosshall figures out what makes mosquitoes flock to us, she can get to work on making them leave us alone. Many of her lab’s proposed solutions sound simple enough, including bracelets that carry long-lasting repellants or traps that can reduce populations, but the breakthroughs may save millions of lives in the developing world—and a lot of itching everywhere else.

This story originally appeared in the Think Small issue of mental_floss magazine. Get a free issue here!

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Big Questions
What Causes Sinkholes?
Mark Ralston/AFP/Getty Images
Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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science
DNA Analysis of Loch Ness Could Reveal the Lake's Hidden Creatures
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Stakeouts, sonar studies, and a 24-hour video feed have all been set up in an effort to confirm the existence of the legendary Loch Ness Monster. Now, the Associated Press reports that an international team of scientists will use DNA analysis to learn what's really hiding in the depths of Scotland's most mysterious landmark.

The team, led by Neil Gemmell, who researches evolutionary genetics at the University of Otago in New Zealand, will collect 300 water samples from various locations and depths around the lake. The waters are filled with microscopic DNA fragments animals leave behind as they swim, mate, eat, poop, and die in the waters, and if Nessie is a resident, she's sure to leave bits of herself floating around as well.

After extracting the DNA from the organic material found in the water samples, the scientists plan to sequence it. The results will then be compared to the DNA profiles of known species. If there's evidence of an animal that's not normally found in the lake, or an entirely new species, the researchers will hopefully spot it.

Gemmell is a Nessie skeptic, and he says the point of the project isn't necessarily to discover new species. Rather, he wants to create a genetic profile of the lake while generating some buzz around the science behind it.

If the study goes according to plan, the database of Loch Ness's inhabitants should be complete by 2019. And though the results likely won't include a long-extinct plesiosaur, they may offer insights about other invasive species that now call the lake home.

[h/t AP]

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