On November 28th, 2017 we learned about

Flying beetles found to swing their legs to tighten their turns

When a bird flies, it tucks its feet close to its body to avoid creating turbulence in the air around it. So do dragon flies. So do large aircraft, even if they’re tucking in wheels instead of feet. Flying beetles, on the other hand, seem to have missed the memo on aerodynamics, because they do the exact opposite, flying with their legs outstretched in all directions. This certainly creates drag, which is why scientists suspected that this akimbo posture must offer some other benefit to beetle flight, like maneuverability.

Turning while tethered

It seemed quite plausible that outstretched legs could play a role in beetle steering, but scientists couldn’t just ask them why they flew that way to get an explanation. To get around this, they simulated flight for a beetle, then watched as it responded to turning either left or right in the air. Insects don’t have the inner ear we do to detect motion, relying almost exclusively on visual stimuli to tell them how they’re moving through space. So a beetle could be glued to a fixed point, and as long as stripe patterns in front of it looked like they were panning to the right or left, the beetle thought it was actually zooming around enough to demonstrate how it uses its legs in a turn.

When “turning” left, the beetle would pull in its right leg, doing the opposite when the visuals were reversed. So instead of simply pretending to not have drag-inducing legs, the beetles apparently put their legs to work, creating a rotational force to change their trajectory. At least, that’s what it looked like the beetles wanted to do, because in this first test they weren’t actually moving. To see if they were actually affecting their rotational inertia with these leg twitches, the insects were untethered and allowed to actually fly.

Controlling cornering

To isolate the role of the beetle’s swinging legs, researchers implanted electrodes to actually take control of their legs’ muscle movement. That way they could trigger the previously seen leg motion on its own, without waiting for the beetle to initiate a turn that might involve other motion. As expected, the swinging legs made a difference in the insects’ flight path, with small turning motions initiated in less than a fifth of a second. They don’t turn with their legs alone, but swinging their legs lets them begin a maneuver faster than they could if using only their wings.

My four-year-old asked: What kind of beetles were they?

In this case, researchers were working with one of the biggest flower beetles in the world, Mecynorhina torquata, which can grow up to 3.3 inches long. The green-shelled natives of Africa are robust aviators, and have been used in a number of different studies, including one that allowed researchers to completely control their movement, effectively turning them into a remote controlled bug.

Source: Why Beetles Fly Like Superman by Jeremy Rehm, Scientific American

On October 29th, 2017 we learned about

Fungus forces beetles to become sexy zombies and spread its spores

This should be obvious, but don’t try to mate with zombies. Even “sexy” zombies doing their best to convince you they’d really like to have kids. You will have no offspring, zombified or otherwise, because the only organism that’s going to be reproducing is the fungus that turned your supposed mate into a zombie in the first place.

Eating flowers, fearing fungi

As outlandish as the above advice may sound, it’s a real concern for Goldenrod soldier beetles (Chauliognathus pensylvanicus). The beetles live in meadows across North America, eating flowers as their main source of food. Conveniently, they also mate on flowers, since it’s a good place to run into another beetle. Amorous females can advertise their intentions by waiting on a flower with their wings open and extended, almost like they’re about to fly away. Unfortunately for the beetles, spores for the Eryniopsis lampyridarum fungus can also be found on these flowers, which is what kicks off a cycle of zombification and unintentional necrophilia.

When the fungus infects a beetle, it triggers some very specific physiological responses to bend the beetle’s body to it’s own ends. The beetle will be compelled to climb to a flower top as it’s body starts to give out. Once in position, the fungus ensures that its host doesn’t just fall off the flower once it’s dead, by forcing it to clamp onto the flower tightly with it’s mandibles. The corpse is just a means to an end though, which is where the beetles’ courtship behavior comes into play.

Making brain-dead bugs more attractive

An inert beetle clamped to a flower isn’t attractive on it’s own, but the fungus makes sure to pretty up its host, whether its male or female. After 15 to 22 hours, the wings will pop out to resemble the pose of a female looking to attract a mate. As an extra touch, the fungus causes the beetle’s abdomen to swell, which is an attractive look to male beetles that seem to prefer larger females in general. This attempt at sexiness doesn’t make zombified males all that enticing, but zombified females do draw a lot of attention from healthy males in the area. The resulting contact with those males is the fungus’ real goal, because that’s how new spores get spread from a zombie female to new flowers across the meadow.

This isn’t the only insect to have it’s brain and body taken over by a fungus, but there are still some questions particular to this pairing. Since the fungus already manipulates the beetles’ behavior, scientists are going to take the opportunity to measure exactly how big a role opened wings plays in courtship by gluing zombified wings shut. The zombie won’t object, and better yet, won’t do anything new that would add unwanted variables to the study.

Source: Fungus uses zombie female beetles to infect males by Bob Yirka, Phys.org

On October 26th, 2017 we learned about

A reexamination of the fossil record finds that cockroaches aren’t so ancient after all

According to popular lore, nothing will ever bring down cockroaches. They’ve supposedly been on Earth since time immemorial, and will be hear long after humans wipe themselves off the map. What’s more, they’ll probably continue living in the ruins of our kitchens just to spite us. Unsurprisingly, careful research is finding that the legendary persistence of cockroaches just isn’t true. In fact, some fabled dates of the roaches’ origins appear to be wrong by at least 160 million years.

The story of cockroaches was thought to have started in the Carboniferous Period, over 300 million years ago. It was a time when much of the planet was constantly warm and humid, which admittedly does sound like something a cockroach would be into. Fish were starting to look more like their modern counterparts, but terrestrial vertebrates were just getting started as proto-amphibians. While the world definitely had plenty of insects at this point, as they seemed to evolve alongside some of the first terrestrial plants 479 million years ago, there’s no evidence of true cockroaches. The closest thing would be a confusingly-named group of bugs called “roachoids.”

Roachoids were cockroaches ancient ancestors to be sure. The beetles resembled modern roaches enough to be given the associated name, but they weren’t strictly the first cockroach. In fact, the roachoid lineage was diverse enough that modern cockroaches are more closely related to a praying mantis than the roach-like insects from 300 million years ago. Aside from the name, part of the confusion in differentiating ancient roachoids from true cockroaches is that many fossil specimens were originally misclassified. It’s estimated that only 25 percent of supposedly ancient cockroach fossils are actually cockroaches, and as these identifications are corrected, the age of roaches will continue to be refined and adjusted.

Cockroaches in the Cretaceous

This isn’t to say that cockroaches are the newest bug on the block. Cretaholocompsa montsecana is the oldest known roach, and it was scuttling around what is now Spain in the Cretaceous period 130 million years ago. That makes it a younger lineage than a Stegosaurus, but older than a Triceratops. No matter who its neighbors were, it probably lived in their shadows similarly to roaches around humans, eating and cleaning up after scraps and waste. There’s a fair chance that there were earlier cockroaches as far back as the Jurassic period, but their lineages seem to have gone extinct, with no descendants alive today.

Beyond the trailblazing of C. montsecana, there isn’t a lot of roach diversity in the fossil record until after the dinosaurs went extinct 65 million years ago. Other cockroach species have turned up from 40 and 50 million years ago, and researchers suspect that most modern cockroach species started to evolve around this time period. None of this makes roaches any more pleasant to discover on the sidewalk or under your sink, but it might influence your thinking about just how immutable these supposed living fossils really are.

Source: Old, But Not That Old: Debunking the Myth of Ancient Cockroaches by Dominic Anthony Evangelista and Manpreet Kohli, Entomology Today

On October 18th, 2017 we learned about

Tactile stealth makes mosquitoes more successful at sucking your blood

In addition to keeping your guts in, germs out and providing a convenient canvas for tattoos and scars, your skin is your body’s largest sensory organ. It’s loaded with different types of nerve cells to pick up tiny changes in pressure that might spell trouble for your body, from a cactus needle to a parasitic insect. Unfortunately for us, insects like mosquitoes have evolved adaptions to our epidermal warning system, giving them a chance to sneak in a bloody snack without drawing our attention.

Sneaky stabbing and sucking

When a mosquito “bites” you, it’s actually piercing your skin with its proboscis. In insects like butterflies, the proboscis is a long, delicate tube that is used to suck up nectar from a flower. In a mosquito, it’s a bit more weaponized, and is actually a sheathed set of six thin needles called stylets. Two stylets have tiny teeth to cut through the skin, but they’re sharp enough that they can slip between your skin’s sensory defenses. The next two stylets push the incision open, followed by a labrum that senses for blood vessels.

Finally, the hypopharynx covers the top of the labrum to make it into more of a tube, as well as drip drool back into your incision. In addition to passing pathogens to our bodies, the drool keeps the blood from coagulating, or clotting, too quickly. This allows the mosquito to get her fill of blood cells, even taking the time to poop out excess water while she sucks.

Soft, delicate departures

A mosquitoes departure is no less specialized, as all that blood would go to waste if we detected the parasite and squashed before it could escape to lay eggs. Many insects, and birds and probably pterosaurs, kick-start their flight by pushing off the ground, or skin, with their legs. By catapulting themselves into the air, they save their wings some work and get moving faster. The catch is that they’re exerting all the force of their liftoff in one quick movement, which means that that force feels more punctuated and noticeable to your skin.

To make their departure as gentle and subtle as possible, mosquitoes shift the work to their wings. 61 percent of a mosquitoes liftoff is powered by its wings, which get to push against the air instead of your skin. Their longer legs than the average fly allow them to push with the same amount of force, but that force can be spread out over a longer amount of time. All these adjustments soften the impact of mosquito take-offs, but without sacrificing speed compared to other flies. The one catch is that a belly full of blood does weigh them down a bit, as they move around 18 percent slower in the air than unladen insects. This means a mosquito’s final escape is just less than one mile an hour, although we’re usually too distracted by the histamine-induced itching to notice.

Source: The physics of mosquito takeoffs shows why you don’t feel a thing by Mariah Quintanilla, Science News

On October 11th, 2017 we learned about

Three repulsive reasons to keep houseflies from coming in contact with your food

So you probably weren’t about to invite a fly to land on your food, or even your body, but were you sure about why you had that instinct? Sure, it’s a good rule to not want any creature to sit in the food you’re about to eat, but houseflies quite literally bring a few extra-gross features to the table. Amazingly, the most concerning of a housefly’s activity isn’t their vomit or possibly even their feces, because the nastiest stuff tends to be stuck to their feet.

Puking on your food

Houseflies (Musca domestica), like other insects, can’t chew like you can. Like tiny, more irritating babies, they need their food to be soft and mushy, but without teeth or even jaws they have to liquefy things chemically instead of mechanically. To soften up a blob of food, they barf up a droplet of “regurgitate,” which is basically digestive enzymes that less revolting creatures would keep inside their bodies, or at least some kind of stabby mouth part. Housefly mouths are only good for lapping and sponging up liquids, so they either leave a bit of enzyme hanging off their tongue to help get at softer food, or spew a bigger dose on food that needs more time to break down.

Pooping on your food

Once the food is soft enough, the fly can then lap it up where it will be further digested in the insect’s midgut. Fly digestion, like yours, produces waste, and flies are likely to poop once they’ve gotten stripped their liquefied meals of their nutritional value. This does not mean, however, that they poop every time they land. They poop frequently enough to create what can look like splatter patterns if you know what to look for, but they’re not defecating every time they touch down on you or your food.

Pathogens on your food

As icky as vomit and feces may be, they’re not the most concerning part of a fly landing on your food. Fly feet and bodies are actually much more likely to carry and spread pathogens like, including bacteria that can cause cholera, dysentery and typhoid. A brief touchdown probably isn’t a huge reason to worry, as not enough bacteria will be transferred to necessarily kick off an infection. However, if a fly has had time to really wander around on your dinner, you might want to eat something else, especially if you’re in the countryside.

The reason locales matter is they can influence just how dirty a fly’s feet are likely to be. Flies love things like feces, decaying corpses and rotting vegetable matter, as they provide both food and places to lay eggs. Contact with these items is where the flies pick up bacteria that they can carry back to you, and in general flies in urban areas have fewer encounters with dead animals and feces, unless your neighbor can’t pick up after their dog. You’ve probably seen a fly vigorously cleaning its eyes, wings and body, but until you can get them to use soapy water, that cleaning won’t eliminate the pathogens that you don’t want to eat.

Source: Cough it Up – Fly Vomit by Nancy Miorelli, Ask an Entomologist

On September 27th, 2017 we learned about

Sap beetles steal snacks from inside unsuspecting ants

Jet ants and sap beetles share a lot of similarities. Both insects depend on trails of pheromones to smell their way to their daily destinations. Both eat honeydew secretions obtained from aphids. Both depend on a regurgitation process to share that honeydew. However, all these commonalities don’t mean the two species always get along, mainly since the sap beetles do all this at the expense of the ants, occasionally triggering rapid, if slightly ineffective, retaliation.

Once a jet ant (Lasius fuliginosus) harvests honeydew from an aphid, it tries to carry it home in a special stomach called a crop. As with birds that regurgitate food for their young, the ants don’t digest the food kept in the crop so that it can be delivered “fresh” for friends back home. of course, the sap beetles (Amphotis marginata) have figured this foraging pattern out, and will hone in on the ants’ pheromone trails in order to intercept honeydew-laden workers for meals of their own.

When a sap beetle encounters an ant, it basically just walks up and requests a snack. Mimicking the movement of actual ants, the beetles tap the ant’s legs and antennae which prompts the ant to lick the beetle’s head. The beetles, as evolution would have it, secrete a liquid from their heads that scientists suspect confirms their ant credentials, allowing them to then force their mouth against the ant’s and wait to be fed whatever honeydew the ant was carrying home in its crop.

The beetles have a pretty high success rate, although they do have a plan ‘B’ if the ant catches on that it’s being tricked. They can pull all their appendages under their wing cover and flatten out against the ground. The ants can’t get at them under this protective shell, and are basically forced to move on to replace their stolen honeydew.

Putting numbers to the pilfering

To make sure these behaviors weren’t anecdotal evidence, scientists captured ants and beetles to more carefully track them in the lab. The honeydew was replaced with a sugary liquid doped with radiation that would allow researchers to trace exactly how much food was in each insect’s body, allowing them to quantify exactly how the ants and beetles interact. They found that the beetles truly have a kleptoparasitic relationship with the ants, doing nothing but stealing the ants’ food. In fact, beetles mooched off ants so well that they generally ate 1.8 times more food than ants relying on relayed sugar water. While it may seem like a one-sided relationship like this would be corrected by the ants, it’s possible that the beetles aren’t demanding enough food to force a change in the system. As long as the ants can still successfully reproduce, the beetles are an annoyance, but not necessarily an evolutionary pressure that will force them undergo radical change, like maybe learning what other ants look like.

Source: ‘Highwaymen’ beetles rob ants of the food in their stomachs by Mary Bates, New Scientist

On August 27th, 2017 we learned about

Ants float through floods by assembling into rafts and towers

As devastating as floods can be to human homes and infrastructure, they basically guarantee evictions for creatures that live underground. As water levels rise, insects like ants can’t lay down sand bags to keep their colony dry, but that doesn’t meant they simply drown. Ants in flood-prone areas around the world instead take advantage of their small sizes and large numbers to build themselves into means of escape, from amazingly durable rafts to living towers to scale new heights.

Floating with your friends

During a flood, a colony of ants will evacuate their underground tunnels and begin transforming themselves into rafts. With no executive planning, ants will rush out to the edge of the existing raft, then grab onto neighbors with their mouths, claws or foot pads. With enough workers, a raft of ants can support themselves, plus larvae and their queen that usually get to ride in the center of the raft for extra protection. Once assembled, an ant raft can hold together for weeks, even without individuals rotating positions within the raft’s structure.

The durability and buoyancy of the raft depends a lot on how hydrophobic ant bodies and hairs are. A drop of water on a fire ant’s head is likely to remain a single droplet, rather than breaking and wetting the ant’s whole body. As a group, this effect can trap significant amounts of air in the spaces between ants, to the point that a submerged ball of ants will carry air underwater with them in the process. Air bubbles trapped on ant body hairs can then be used for respiration and to increase buoyancy, keeping even 500,000 ants something approximating “dry” until they find solid ground to land on. If anything, the biggest risk of being in the water is fish, who can pick off ants that protrude from the edges of the raft.

Climbing as a colony

For all the resilience an ant raft provides its… members? (occupants?) it doesn’t work in every scenario a displaced colony might face. When ants find something solid and vertical, like a plant stem, they can start building themselves into a sort of bell-shaped tower. As with the rafts, each individual isn’t working with centralized directions, instead scrambling around to meet a couple of conditions as best it can: one ant can support up to three peers, if linked ants can’t surround the stem with linked arms, the tower needs more layers, and if you sink to the bottom of the pile, climb up again.

The squishiness of the towers means they’re not so much structures as much as processes. Tagged ants were tracked as they moved through the tower repeatedly, and it seems that the whole thing isn’t as static as a raft, but it’s enough to help ants reach new heights that might otherwise be inaccessible. Of course, if the surface of their new scaffolding doesn’t require a tower, they’ll skip it. People have found out the hard way that poking at ant rafts with an oar will very quickly lead to whole new set of unwanted passengers. Even though they can make their own rafts and towers, it seems that these ants are still appreciative of any assistance people can inadvertently offer until things dry out.

Source: How do fire ants form amazing towers and rafts without a master plan? by Craig Tovey, The Conversation

On August 23rd, 2017 we learned about

Lace sheet weaver spiders manipulate moths with their bright white webbing

The lace sheet weaver spider (Psechrus clavis) basically does what its name describes, although that’s really only half the story. Rather than messy tangle webs or circular orb webs, the sheet weaver makes a large, flat web that is usually suspended just over the ground, usually in shadier locales. It’s an unusual arrangement, especially since this spider likes to dine on flying bugs like moths, who presumably would be easier to catch mid-flight in a vertical web. However, experiments have found that the horizontal webs have a special property to help pull moths out of the sky.

As much as a horizontal web may look like a safety net, its success at snaring moths is probably due to looking like open space. Moths don’t have the greatest eyesight, and seem to navigate in the dark by making crude judgments about the amount of open space ahead of them. Having evolved in a world without artificial lighting, open space at night is generally going to be lighter than the dark silhouettes of trees, rocks and the ground. So when a moth is flying at your porch light, it’s likely very confused why this theoretically empty space is somehow solid enough to bang into.

Like the sky, only stickier

At some point the spiders stumbled upon this weakness in moth navigation, and can now use it against them. Their horizontal webs are notably bright and reflective, and researchers hypothesized that that white coloration looked light enough at night to convince the moths it was a safe place to fly. This was tested by covering a set of P. clavis webs in charcoal powder to make them dark black, then comparing how that new coloration affected the number of moths captured in a night. As suspected, the lighter webs caught a lot more prey, indicating that the white webs were more attractive.

The next step is to compare coloration to brightness. Some spiders make themselves, or their webs, look attractive with color for daytime hunting, but these nocturnal traps may instead be based on brightness. More tests are needed, but researchers want to now confirm if it’s the amount of light reflected, and not the specific white hue of the webs, that manages to convince moths that their final resting place is somehow a safe haven.

Source: Spider’s web uses optical illusion to lure nocturnal moths by Karl Gruber, New Scientist

On August 7th, 2017 we learned about

Honeybees can compare quantities from four down to zero

As bees fly through an area to look for nectar, they’re not just listening to their stomachs. Like a good explorer, they’re taking mental notes about where to find the best food supplies so that they can share the good news with the rest of the hive. Their assessments may be more than abstract judgments too, as honeybees have been found to be able to compare specific quantities between one and four. This allows bees to effectively count up to four flowers, on par with the capabilities of most dogs. New research has found that bees can take one big step further though, as they can also understand zero.

Selecting fewer shapes

To test how well bees could count, they were first trained to seek out smaller quantities. Images of different numbers of shapes were displayed at two feeding stations, with the lower number of shapes always being paired with a tasty sugar-solution. Higher numbers were paired with quinine to reinforce the pattern more quickly, and bees regularly flew to the correct, smaller quantity at least 80 percent of the time. What’s more, they were able to correctly compare quantities when the winning option showed no shapes. This may seem obvious, but understanding that “no shapes” is a quantity that can compared is a feat only seen in humans, chimpanzees and monkeys, all of whom have a lot more brain to work with than a tiny bee.

Few can make note of nothing

Understanding that zero is less than one may seem obvious, but that’s largely because you’re used to the idea that zero is a number. Zero wasn’t really recognized as a number until the fifth century A.D. in India, and managed to elude Europeans until the year 1200. Mayans also came up with zero in the first few centuries A.D., but it wasn’t innately part of human mathematics. This doesn’t mean that our honeybees are on the verge of working out multiplication or negative numbers (negative flower counts?), but it does shake our understanding of what kind of brain is necessary to handle a quantity of none.

At this point, it’s also not clear what bees might be counting. Keeping tabs on flower counts may be an option, although it may also be useful for tracking the dances bees perform to communicate their discoveries to each other. We know that bee brains can handle these operations, but figuring when they employ these math skills may be much harder.

My four-year-old asked: Why does zero matter?

This is a tough question to answer for someone still working on counting to 12. To start, it makes dealing with large numbers much easier, as we don’t need as many unique digits. We don’t need a character for ten because we can use 1 and a 0. Zero has also allowed us to deal with numbers less than one, including decimal fractions and negative numbers. It’s also critical for… oh wait, four-year-old.

Zero lets us keep track of amounts smaller than one, as well as work with much bigger numbers more easily. We’ll come back to this in a few years maybe…

Source: Bees are first insects shown to understand the concept of zero by Sam Wong, New Scientist

On July 12th, 2017 we learned about

Tomatoes infuse their leaves with toxins to turn insects against each other

Tomato plants do not want to be eaten. The 31 pounds of tomatoes each American gobbles per year is fine, because that helps with seed dispersal and gives us a reason to plant more tomatoes. The problem for the plants is that too many bugs bypass the red fruit and eat the leaves of the plant, leaving it with no way to produce its own food through photosynthesis. To defend themselves, the plants have found a way to control the bugs’ appetites and populations— they get the bugs to eat each other.

This pest-control concept is actually based on normal behavior in various pest herbivorous insects, like mottled willow moth caterpillars (Spodoptera exigua). When these bugs can’t get enough nutritious food, they don’t really have the means to travel to find something better, as they’re trying their best to hoard calories in preparation for metamorphosis. So when the leaves are scarce, or just low enough quality, the insects will start eating each other instead as the last local source of nutrients and calories.

Turning up the toxins

Tomato plants (Solanum lycopersicum) have evolved to exploit this quirk of pest ecology. Tomatoes in danger can start producing extra toxins in their leaves that make them less nutritious to eat. Manipulating leaf-quality like this then convinces caterpillars it’s time to switch to cannibalism. In experiments, caterpillars offered more toxic leaves started munching caterpillar corpses much sooner than their peers. From the tomato plant’s perspective, adjusting the chemistry of leaves may be energetically costly, so they don’t make their leaves less attractive all the time. When circumstances demand it, this strategy does work well enough to make a measurable difference in just how much each plant gets eaten.

The last layer of this defensive strategy is that a tomato plant doesn’t need to get bitten to start raise its defenses. Like a variety of other plants, tomato plants can warn each other about the arrival of herbivores. They emit a compound called methyl jasmonate (MeJA) that can be detected by nearby plants, giving them a chance to start toxifying their leaves before the insects begin their buffet. There is some interest in manipulating this warning system, since presumably farmers could release MeJA to warn crops whenever they wanted. However, it might be best to follow the tomato plants’ lead on this, since constant warnings and toxic leaves could stress the plants while selecting for only the hardiest, toughest insects around.

Source: Plants turn caterpillars into cannibals by Laura Castells, Nature