How bees play telephone to form a swarm

Honeybees use pheromones and flapping wings to tell each other where to find the queen — so they can all be together.

How bees play telephone to form a swarm
Kid: Wow! That’s super interesting…but can you help me get rid of them? My mom needs to drive us home.  Orit Peleg: Why, yes I can! I’m not just a biologist; I’m an interdisciplinary biologist. I have lots of talents. Let me just put in a call to my colleagues at the University of Colorado, Boulder. But are you sure your mom doesn’t want to see this first? It’s kind of special.
My colleagues and I were studying bee swarms in the lab. And we noticed that the bees use pheromones ― chemical communication ― to talk to one another. That isn’t unusual. Lots of animals, including us, use pheromones.  Queen bee: Come to me, my hive!  The queen sends out pheromones to tell her workers where to find her. But these chemicals dissipate quickly. So we wondered, how would a worker bee far away know where its queen was?
Panel 3: We built an arena in the lab. At one corner, we placed the queen. At the other, workers. Worker bees: Without our queen, our hive will fall apart. Where is she? Queen bee: Here I am!
Panel 4: Then we watched as the worker bees swarmed around their queen. We used artificial intelligence to track the insects and their behavior. Worker bee: Now we can all get cozy together. Queen bee: I missed you all.
Panel 5: This relies on a behavior called “scenting.” It starts when a worker bee gets close enough to smell the queen’s pheromone. Then the worker produces its own pheromone. The bee directs the chemical by lifting its abdomen and flapping its wings.  Worker bee: This way, friends! The queen is just up ahead.
Panel 6: Then, as more bees detect that pheromone, many also halt and start producing the chemical. Eventually, this big game of telephone produces a map to the queen. And the other workers can follow that map to become a swarm.  Queen bee: You’re almost here!
Panel 7: Kid: Wow! That’s super interesting…but can you help me get rid of them? My mom needs to drive us home. Orit Peleg: Why, yes I can! I’m not just a biologist; I’m an interdisciplinary biologist. I have lots of talents. Let me just put in a call to my colleagues at the University of Colorado, Boulder. But are you sure your mom doesn’t want to see this first? It’s kind of special.
JoAnna Wendel
Source : Science News for Students More   

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Copper ‘foam’ could be used as filters for COVID-19 masks

The lightweight new material could serve as a washable and recyclable, eco-friendly alternative for many current mask filters.

Copper ‘foam’ could be used as filters for COVID-19 masks

Face masks have become a vital tool in slowing the spread of the virus that causes COVID-19. They help filter or block spit or mucus droplets that carry infectious particles. Even homemade fabric masks can do a good job. But many are not very durable. Now, researchers have come up with a new sort of filter for use in masks. Made of copper, it’s sturdy and lightweight. The sponge-like material also is easy to clean and can be recycled. In tests, it outperformed the filtering ability of a standard N95 mask. It might even trap and kill bacteria, its developers say.

See all our coverage of the new coronavirus outbreak

Masks to guard against viruses can be made of many different materials. Some fabric ones even use extra layers — often cotton, silk or some synthetic — to boost their filtering prowess. Others use paper similar to coffee filters. With so many people now being asked to wear masks during the pandemic, researchers began scrambling to identify new and better filters. Kai Liu was among them.

This materials scientist thought his team at Georgetown University in Washington, D.C., had a head start. They already had been testing materials to filter small particles out of polluted air.

Recalls Liu, “We saw that small droplets carrying viruses were the same size as some atmospheric pollutants.” Right away, he says, “we thought we should check our materials to see if they might make good filters for face masks.”

A lightweight form of “copper foam” (sample resting on plant fibers) could render facemask filters washable or recyclable. Malloy et al/ Nano Letters (2021)

Liu’s team soon began cranking out new batches of a material they call copper foam.

They started with templates to make copper nanowires. The diameter of each wire was typically about 200 nanometers, says Liu — or less than one-millionth of an inch. After dumping those wires into ultrapure water, they flash-froze the mix in liquid nitrogen. Afterward, they put the copper-filled ice in a vacuum chamber. It drove off the water to freeze dry the now loosely packed mass of tiny copper wires. Finally, they heated the mass of wires to 300° Celsius (572° Fahrenheit). This fostered chemical reactions that helped bind them into a mesh.

microscopic images of copper foam
An open mesh of copper nanowires (top; close-up at bottom) can filter small droplets better than a hospital-style N95 mask, a new study suggests.Malloy et al/Nano Letters (2021)

Unfortunately, that mesh was super flimsy, says Liu. Tests showed it would collapse if someone breathed on it. Obviously, that would not work well in masks. So, the researchers kept tweaking the process.

They bathed the weak mesh in a liquid that included copper ions. Then they sent an electric current through this chemical bath. That deposited more copper onto the nanowires, thickening them. Liu says it also helped weld the wires at points where they touched. In tests, some samples of this material could now support about 10,000 times their own weight without collapsing. That was true even when the material was 85 percent air.

More importantly, this 85-percent-air foam filtered out tiny particles. A sample 2.5 millimeters (0.1 inch) thick captured 97 percent of particles between 0.1 to 0.4 micrometers in diameter. Such super-small particles not only are the hardest to trap but also the size of aerosol droplets that can carry virus particles. These particles don’t get trapped by the material’s tiny pores, Liu explains. The particles are instead attracted to the enormous surface area that the nanowires provide. They get stuck there on it as they try to move through the wire maze between the outer and inner edges of the filter. Liu and his colleagues described their innovative new foam April 14 in Nano Letters.

Another approach

The Georgetown team developed “an interesting and innovative way to produce their material,” says Semali Perera. She’s a chemical engineer at the University of Bath in England. She wonders, however, if it would be hard to scale up the process to make really big batches and large pieces of the thin foam for use in masks.

Perera’s team is taking a different approach to germ filters. Theirs were initially targeted to collect and kill bacteria. Now they’re being designed to trap viruses, too.

One promising material her team is exploring is a plastic-like foam made out of a polymer called polyimide. To give it a germ-killing punch, the researchers added copper and nickel. Nickel helps slow the growth of bacteria, and copper helps kill them. Those metals make up about 80 percent of the material, says Perera. The plastic-like polymer helps bind the metal atoms together.

Instead of using a multi-step process to make its material, this group mixes its ingredients in one container all at once. A chemical reaction that generates large amounts of carbon dioxide makes the material frothy, Perera notes. As it foams, it expands into a mold. Within three seconds it hardens into its final shape. To make big batches, the researchers merely mix more of the ingredients and then cook them up in a bigger pot.

Perera and her team are working with companies to design new products. One potential use for their material might be filters for home air-conditioners.

This is one in a series presenting news on technology and innovation, made possible with generous support from the Lemelson Foundation.

Source : Science News for Students More   

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