Tag Archives: fly

Danger sign.

Scared? Here’s how your brain decides whether you freeze, flee, or fight

New research sheds light on how our brains react when faced with danger.

Danger sign.

Image credits spcbrass / Flickr.

Hear that? If you listen really hard, you can actually make out the sound of nothing hunting you right now. Safely ensconced in our society, we tend to take this for granted. Make no mistake, however: it’s anything but.

That’s exactly why we (and basically every other animal) evolved from the ground up with self-preservation in mind. Despite our sheltered existence, the brain circuits that generate our responses to perceived threats are still very much alive to this day. In a bid to better understand how these networks operate, and why they work the way they do, researchers at the Champalimaud Centre for the Unknown (CCU) in Lisbon, Portugal, set about to terrify the pants off some very tiny flies.

Fly, fruit fly!

“Just like any other animal in nature, our reaction to a threat is invariably one of the following three: escape, fight or freeze in place with the hope of remaining unnoticed,” says Marta Moita, co-lead author of the study.

“These behaviours are fundamental, but we still don’t know what the rules of the game are,” adds the study’s first author Ricardo Zacarias. “In each situation, how does the brain decide which of the three strategies to implement and how does it ensure that the body carries it through?”

Fruit flies (Drosophila melanogaster) might not seem like the coolest or smartest organism out there — in all honesty, they’re not — but they do have a few saving graces: they’re easy and cheap to care for in large numbers and they’re low maintenance. They also procreate fast and with a fury, so there’s always plenty of them to experiment on.

Given their simpler natures (and wings), Moita admits, many people “believed that flies only escape”, but the research showed that’s not the case. They devised an experiment in which the flies didn’t have the option of flying away and then spooked them to see their reaction.

The flies were placed in covered dishes and were then shown an expanding dark circle, which ” is how a threat looks like to a fly,” Moita explains. With flying away out of the question, the flies froze, the team reports. In a perfect mirror of the same behavior in mammals, birds, and several other species, the flies remained completely motionless for minutes on end. There’s no doubt as to why the flies froze since they would maintain positions that were obviously awkward and uncomfortable for them, such as half crouches, or holding a leg or two “suspended in the air,” Moita explains.

Some flies, however, decided to make a dash for it.

“This was very exciting,” says Vasconcelos, “because it meant that similarly to humans, the flies were choosing between alternative strategies.”

The next step was to take a closer look at what triggered each response. For this goal, the team used machine vision software to produce highly-detailed accounts of each fly’s behavior. Analyzing this data revealed that the flies’ response was determined by their walking speed at the moment the threat appeared. If the fly was walking slowly, it would freeze. By contrast, if it was traveling at speed, it would attempt to run away instead.

“This result is very important: it is the first report showing how the behavioural state of the animal can influence its choice of defensive strategy,” Vasconcelos points out.

The team later identified a single pair of neurons that underpin these defensive behaviors. The pair — with one neuron on each side of the flies’ brain — decided whether the flies would freeze or not. When the team inactivated these neurons, the flies stopped attempting to freeze and just ran away from threats all the time.

When the team artificially forced the neurons to stay active all the time, even without a threat being present, the flies would freeze depending on their walking speed — the fly would freeze if it was walking slowly, but not if it was walking quickly.

“This result places these neurons directly at the gateway of the circuit of choice,” says Zacarias.

“This is exactly what we were looking for: how the brain decides between competing strategies,” Moita adds. “And moreover, these neurons are of the type that sends motor commands from the brain to the ‘spinal cord’ of the fly. This means that they may be involved not only in the choice, but also in the execution”.

The findings should help provide a starting point for identifying how the brains of other species handle defense, the team explains, as “defensive behaviors are common to all animals”.

The paper “Speed dependent descending control of freezing behavior in Drosophila melanogaster” has been published in the journal Nature.

The humble fly carries even more diseases than we thought, new study shows

We all know that flies are nasty and annoying, but most people just brush them off. Well, we might want to be more careful with them, as a new study shows that the two most common fly species can harbor more than 600 different bacteria.

Has this guy landed on your food? If so, you might want to think twice before eating. it. Image credits: Jon Sullivan.

Bacteria shuttles

Most people are aware that flies can carry dangerous pathogens, but few people are aware of the extent of that danger. To shed some light on said pathogens, researchers used DNA sequencing techniques to study the collection of microbes found in and on the bodies of the house fly (Musca domestica) and the blowfly (Chrysomya megacephala). In total, they analyzed DNA found on 116 flies from three different continents. They found that the house fly, which is virtually ubiquitously in the world, can carry up to 351 types of bacteria, while the blowfly, limited to the warmer parts of the world, carried 316. All analyzed individuals carried a large number of pathogens.

“We believe that this may show a mechanism for pathogen transmission that has been overlooked by public health officials, and flies may contribute to the rapid transmission of pathogens in outbreak situations,” said Donald Bryant, Ernest C. Pollard Professor of Biotechnology and professor of biochemistry and molecular biology, Penn State.

Stephan Schuster, former professor of biochemistry and molecular biology, Penn State, and now research director at Nanyang Technological University, Singapore says that the flies’ legs especially can carry bacteria from one surface to another.

“The legs and wings show the highest microbial diversity in the fly body, suggesting that bacteria use the flies as airborne shuttles,” said Schuster. “It may be that bacteria survive their journey, growing and spreading on a new surface. In fact, the study shows that each step of hundreds that a fly has taken leaves behind a microbial colony track, if the new surface supports bacterial growth.”

Researchers used a scan electron microscope to find where bacterial cells and particles attach to the fly body. The electron microscope captures an up-close look at the head of a blowfly in this picture. Image credits: Ana Junqueira and Stephan Schuster.

Since both flies are carrion species, they’re quite likely to pick up a swarm of bacteria and then pass them on to us. They also use feces or decaying, rotting corpses to nurture their young, which not only makes them pretty disgusting but also dirty and dangerous. Feces and decaying organic matter are a haven for flies, but they’re also a haven for bacteria (including nasty ones).

However, researchers say that there is some good news to come from their research. They believe that flies could be used as “drones” to research how pathogen-prone an environment is. Basically, they say we could release clean flies into an area, they would naturally pick up the bacteria from said area, and scientists could recapture and analyze them, thus learning what pathogens hide there.

The study also revealed that the two fly species share over 50 percent of their microbiome and that flies from urban areas tended to carry more bacteria than their rural counterpart. The potential, then, for flies to carry diseases may increase when more people are present. But most importantly, researchers want the general population to pay more attention to flies and their interaction with our food.

“It will really make you think twice about eating that potato salad that’s been sitting out at your next picnic,” Bryant said. “It might be better to have that picnic in the woods, far away from urban environments, not a central park.”

The article was published in Scientific Reports.


Scuba diving flies use bubbles to feed underwater

For most insects, going beneath the water surface would be suicide. But for these flies in California’s Mono Lake, it’s a walk in the park. They use protective air bubbles to protect their bodies using a phenomenon called superhydrophobicity.

Fly divers

A fly in an air bubble. Credits: Floris van Breugel/Caltech.

More than a century ago, as he was traveling through America, Mark Twain discovered an unusual phenomenon at Mono Lake, just to the east of Yosemite National Park. He witnessed large group of black flies dipping into the lake, documenting it in his travel memoir “Roughing It.”

“You can hold them underwater as long as you please — they do not mind it — they are only proud of it. When you let them go, they pop up to the surface as dry as a patent office report.”

What Twain observed wasn’t just a quirk of nature, it was an impressive and complex interaction between the chemicals in the water and those inside the flies, researchers report.

Mono Lake is an unusual place. It’s three times saltier than the ocean and about as basic as ammonia. Yet even this inhospitable environment houses some species, including shrimp-eating black flies. Alkali flies, Ephydra hians live along the shores of the lake and walk underwater, encased in small air bubbles for grazing and to lay eggs. Scientists have been wondering for a long time how they manage this impressive feat and now, they’ve finally found the answer.

Caltech biologist Michael Dickinson teamed up with Floris van Breugel (now at University of Washington) to study these flies, not only because they dive underwater, but also because they are a crucial part of their local ecosystem.

“Mono Lake has a very delicate and unique ecosystem,” says van Breugel. “Conservationists have fought hard to prevent its loss. We were interested in the Mono Lake flies not only because their behavior is so unusual, but because they are a crucial species for the lake’s ecosystem and food web. Mono Lake flies are a crucial component to the local ecosystem, acting as a food source for spiders and for migratory and nesting birds.”

The briny water actually creates the perfect conditions for flies to go beneath the surface. No fish live in Mono Lake, but algae, bacteria, and shrimp are quite abundant. For flies, this means that there are no predators, but there’s a lot of available food. However, flies need to overcome a big obstacle: surface tension.

Surface tension

Surface tension is the property of a fluid to resist an external force, due to the cohesive nature of the water molecules.

It’s hard to directly experiment surface tension with our human bodies — being so big and dense, once we go into the water, we just sink. But for flies, that’s a different story. Flies are so light that they can actually float on water, due to the surface tension. To a fly, water is dense, sticky, and very hard to penetrate and evade. So the blackflies developed two unique adaptations to overcome these problems: they’re very hairy, and they’re covered by a waxy substance that is as repellent as paraffin. This substance makes the flies hydrophobic — it repels water. This allows them to stay dry, making the flies able to defeat the surface tension and escape the water. The hair also helps by repelling the carbonate-rich water, and the flies also have large claws which allows them to crawl underwater rocks while resisting the naturally buoyant force of the bubble.

Dickinson and Bruegel set up an experiment, plunging unfortunate flies into different wet surfaces, testing the blackflies’ ability to escape such environments and comparing them with the performance of other, closely related flies. They found that no other fly has the same ability. Furthermore, when they rinsed the blackflies with a solvent (hexane) to dissolve their wax, they lost their ability to form a superhydrophobic bubble suggesting that the wax is essential in the process.

Researchers believe that many other fly species might have had this ability, but they lost it because there was simply no motivation to keep it. Going underwater is tiring and risky, as fish can easily gulp you out. The one thing which encouraged Lake Mono’s blackflies to continue was the absence of fish.

“It’s not that Mono Lake flies have evolved a new and unique way of remaining hydrophobic–it’s that they’ve amplified the normal tools that most insects use,” says Dickinson. “It’s just a killer gig. There’s nothing underwater to eat you and you have all the food you want. You’ve just got to dive in perhaps the most difficult water in which to stay dry on the planet. They figured it out, and so get to enjoy an extremely unique life history. It’s amazing how the evolution of such small-scale physical and chemical changes can allow an animal to occupy an entirely new ecological niche.

Still, the questions of Why and How still linger. Researchers say their work answers one question but opens up even more.

“We could go in the materials science direction and study the chemistry of the waxes that the insects use,” he says. “But there’s also some really interesting neurobiology–it is such an incredibly weird thing for a fly to deliberately crawl underwater.”

Journal Reference: Floris van Breugel and Michael H. Dickinson. Superhydrophobic diving flies (Ephydra hians) and the hypersaline waters of Mono Lake.  doi: 10.1073/pnas.1714874114


Fossil Friday: Diptera brachycera in amber

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Image via flickr user James St. John

Amber is the fossilized from of tree resins. While fresh and viscous, it often gulps up pollen, plant material and even insects — such as this Diptera brachycera.

The bug was discovered in the amber formations of Yantarnyi, western Russia, meaning it lived in the Lutetian (41.3-47.8 million years ago) stage of the Middle Eocene. The milky-white film that forms around the insect is decay coating, a good indicator of genuine Baltic amber.

Along with Diptera, the amber incorporated a lot of tiny things known as stellate trichomes — the fuzzy, spiny object in the left of the photo for example. They’re basically small pieces of ancient oaks, such as epidermal hairs on flowers or leaf buds that they shed and got caught in the resin.

Diptera specimens are still alive and kickin’ today, and some of them are getting coated in amber as we speak! A nice reminder that fossils are still being formed for future paleontologists to uncover.


Image via flickr user James St. John

These futuristic flying pods could one day redefine transportation

Imagine if, instead of driving in the crowded traffic or taking the bus to work, you could just fly, above the street. That’s the idea behind skyTran, a self-driving monorail that hopes to revolutionize the way we think about transportation.

Image via SkyTran.

According to CEO Jerry Sanders, the system could turn a two-hour car commute into a 10-minute trip, traveling at 150 mph (241 km/h) some 20 feet above the ground (6 meters).

“Everyone hates commuting, but there are no solutions,” Sanders said in an interview. “The only way to get around traffic is to literally go above it.”

In case you think the technology is a bit sci-fi, you couldn’t be further from the truth. A 900 foot test station (274 meters) will be set up in Tel Aviv, Israel, by the end of the year, with real-scale systems potentially being deployed by 2018 in India, France, and the US.

Image via SkyTran.

The technology uses magnets to hang from slender rails, with a single pod using about as much electricity as two hair driers. If that sounds somewhat familiar, you’re probably thinking about Maglev trains. Maglev (Magnetiv Levitation) is an innovative transport method that uses magnetic levitation to move vehicles more easily. Because the trains don’t touch the ground, the friction is greatly reduced, and the vehicle travels along a guideway, with the magnets creating both lift and propulsion.

The skyTrans’ aluminum rail would levitate with just gravity, magnets, and a short burst of electricity. After a short burst of electricity speeds it up to 10 mph, it will accelerate using a process called passive magnetic levitation. But it’s not just that it’s fast and it consumes very little electricity – but constructing it is easy as well. NASA claims it would only cost about $13 million per mile to build, whereas a subway system can cost at least $160 million for the same distance.

The tracks could go to important locations, like airports, hospitals or universities, but at one point, it could even connect individual apartments. Construction lasts for only a few days, doesn’t take up a lot of space, and so far, NASA has developed four different types of steel and aluminum pods — one that sits two people, one that sits four, one for the disabled, and one for larger cargo. The goal is to have the system learn from itself – how many people use it at what hours – and adjust its pod delivery accordingly.

“No more road rage. No more pollution,” Sanders says. “People can get where they want to go with a smile on their face.” In cities where people spend hours in traffic, skyTran may just offer the alternative we need.

Amazing Time-lapse Shows A Fly Emerging From Its Pupa

It’s one of those videos that’s either mesmerizing, disgusting… or a bit of both. But no matter how you look at it, the video is quite interesting. It shows a fly emerging from its pupa:

The pupa In the life of an insect the pupal stage follows the larval stage and precedes adulthood. It is the life stage of some insects undergoing transformation and can last anywhere between a few days and several years.

Another thing that’s interesting about flies is the position of their genital organs, especially in females. The genitalia of female flies are rotated to a varying degree from the position found in other insects. This torsion may lead to the anus being located below the genitals, or, in the case of 360° torsion, to the sperm duct being wrapped around the gut, despite the external organs being in their usual position.

The fly: Musca domestica. Image via Wiki Commons.

New technique sheds light on how snakes “fly”

It’s a well known fact that snakes can “fly”, gliding even more than 100 meters sometimes from branch to branch, but exactly how they are able to achieve such a remarkable feat has dazzled researchers for quite a while. A new study using an unprecedented filming, 3D modeling, real and fake snakes showed how snakes move and angle to obtain the optimum lift.

In order to do this, biologists analyzed five species of Chrysopelea, observing how they twist their ribs and flatten their body in mid air. This is not quite an uncommon feat among other species, but few of them achieve the height of the Chrysopelea.

“Other snakes flatten their bodies as well,” said Jake Socha, a biologist at Virginia Tech. For example, king cobras can flatten their hoods for defensive purposes.

The team filmed the snakes while they were gliding and compared them to the 3D models they created, not only to see how they jump, but also how they can prepared their descend and achieve such an amazing precision. They found that snakes position their bodies at 25-degree angles as they fall, with their heads up and tail down. Researchers compared this to when you stick your hand out of a moving car and tilt your palm slightly upward.

“You hand is now angled to the oncoming flow, and that angle helps push the air down,” Socha said. “As a consequence, your hand goes up.”

“Our research suggests that, with an S configuration, [the snake] gets more lift than it would if it were a straight snake,” said Socha, whose initial flying-snake research was funded by the National Geographic Society’s Committee for Research and Exploration. (The Society owns National Geographic News.)

The study may also have a military importance, though this wasn’t the original purpose; for example, understanding how snakes “fly” may lead to better gliding air vehicles.

“This is amazingly interesting and curious, and it’s not at all clear how it works or how it could have evolved,” he said. “I’m just trying to answer these basic questions.”

Longest unmaned flight record broken



QinetiQ claims they have broken this record, by using a really light plane built of carbon fiber, powered by solar panels, nicknamed “Zephyr”. The aircraft stayed in the air for 83 hours and 37 minutes, which is more than twice the previous record.

Zephyr also broke the previous record by approximately 54 hours, but that attempt remaine unofficial, which is probably what will happen to this attempt too, because they didn’t meet the criteria set by the world air sports federation.

But that doesn’t seem to affect them too much, because they were more interested in something else.

“We were concentrating more on the flight than the record,” he said.

The performance they achieved is definitely worth noting and there’s a big chance they will achieve an even better time.

The plane weighs 30 kilograms, it is directed by auto pilot, and it reached an altitude of more 60,000 feet (18,000 meters). During the day it got the energy form the sun, and at night they used some rechargeable lithium-sulphur batteries. This technology could be very useful in reconnaissance and communications.