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Why don't bees sting hornets for defense?

Why don't bees sting hornets for defense?


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Why don't honeybees sting hornets for defense when their hive is attacked? It seems like a good weapon against bigger animals - why not against hornets?


Smithsonian mag says that the bee stings can't penetrate through the predator hornet's armor, which is simply a case of the hornet's armor being tougher than the blunt barb of the bee sting. https://www.smithsonianmag.com/smart-news/invasion-murder-hornets-180974809/

Here's a good research:"

To examine their behaviors of penetrating into different materials, we performed penetration-extraction tests and slow motion analyses of their insertion process. In comparison, the barbed stings of honey bees are relatively difficult to be withdrawn from fibrous tissues (e.g. skin), while the removal of paper wasp stings is easier due to their different structures and insertion skills. The similarities and differences of the two kinds of stings are summarized on the basis of the experiments and observations.

Some research suggests that bee stings have evolved to ward off vertebrates, physically and chemically. Wasps have more slender stings and perhaps that's why the hornets prefer bees nests.

Actually, a lot of insects have phenomenally hard keratin, beetles and the bulldog raspy cricket, as far as i know, even parasitoid wasps which have specialized stings evolved to cope specificially with insects are more common on caterpillars and spiders than strongly armored animals like big beetles.


Much like humans, bees and wasps get hot when the weather is hot. To keep themselves cool, they seek out sources of water to take a dip in and drink from.

Their presence around your pool is also due to their attraction to backyards. Flowers and grass are big draws for bees and wasps, providing a mini-ecosystem for them to live in and materials to build their nests.

While most people think that bees and wasps are out to sting them, this is a self-defense tactic as they only do this when provoked.

Fun fact: Bees will actually die after they sting you, as they try to pull themselves out of the sting, ripping apart their abdomen. Wasps, like yellow jackets and hornets, are a bit more temperamental. They’re very territorial and, unfortunately, don’t die after jabbing you.


Determine Why There Are Bees Around Your Car in the First Place

There are a few reasons why bees could be flying around or near a car in the first place. The most likely reason is that there are bees flying around a car in search of nectar. While a car definitely doesn’t produce any nectar, there may be something that contains sugar that was spilled on or in the car.

VERY IMPORTANT: Please consult with a local beekeeping professional trying to remove any bees or wasps by yourself.

If you’re finding that you’ve got a few open bottles or cans lying in or around your car, then the first step would be to get rid of any possible trash around the car to ditch any attractants for the bees.

In addition to being attracted to sugary foods, bees are also attracted to any sweet-smelling air freshener, perfume or cologne. The scent reminds bees of flowers and makes them think it’s time to pollinate.

If you have a sweet or flower-scented air freshener in your car, try getting rid of the scent for a few days and see if the bees go away. If you’re wearing a perfume or cologne scent that could be considered to have a sweet or flower smell to it, then try switching scents for a few days to see if that helps.

n rare occasions, bees can actually create a nest out of your car and make a home out of it. Instead of making a hive or taking shelter in a tree, bees will sometimes find your car as a great solution to build their colony.

While this is unlikely, It’s much more reasonable that there is a bees nest nearby where your car is parked.

Before going and looking for the nest, it’s important to note what kind of bee you’re seeing flying around your car, so you know where to look for the nest.


Do bees always sting first and ask questions later?

Because stinging means certain death, honey bees won’t sting unless they absolutely have to. According to EarthSky, honeybees only really resort to using their sting when they perceive a threat to the hive. As a result, most foraging honeybees won&apost even attempt to sting if you catch them in the midst of a pollen harvest. Out there, on their own, the hive is not in danger, so they don’t need to sting. If they get swatted or stepped on, though, they will likely take that final stab at vengeance.


Bee Venom and the Chemistry of OUCH!

It’s the price we pay for those beautiful jars of honey. Bees aren’t “seek and destroy” insects. They really aren’t itching for a fight, and are quite content to ignore humans. After all, they have work to do. We’re basically a nuisance to them, so stinging is really a last resort for a bee. But, they are, in the end, social insects and protecting the hive is Job 1. So if a worker bee senses a threat, it will sting and then use alarm pheromones to call in the cavalry. It’s these chemical weapons in the bee’s arsenal that have scientists fascinated. Bees are remarkable, so it’s little wonder that their venom is proving to be an amazingly complex and useful substance.

Bee venom is mostly water-88% to be exact. Because of this water solubility, bees sting in moist tissue in order for the venom to disperse effectively. Unfortunately, that’s why the venom works so well on humans – we have lots of nice moist tissue. Painful to think about, huh? Unlike alarm pheromones, bee venom is odorless with a pH of 4.5 to 5.5 which can make it slightly acidic. Because of this acidity, some home remedies advise using a baking soda paste on stings to neutralize the stings. Most scientists doubt the effectiveness of such topical treatments. (That’s because the venom is injected into skin and not onto skin.)

The allergen in bee venom that causes the main “ouch” is melittin. It’s by far the most abundant ingredient in bee venom – 50% of venom’s dry weight comes from melittin. Melittin causes red blood cells at the sting site to burst and the blood vessels to expand. This blood vessel expansion is why some people have a dangerous drop in blood pressure after bee stings. And, unfortunately, melittin isn’t the only ingredient in bee venom that causes pain. Phospholipase A2 is another protein that works with melittin to destroy cell membranes at the sting site. This ingredient, which makes up 12% of venom, causes pain and inflammation.

But wait – the pain from that one sting isn’t quite over yet. 9% of bee venom consists of histamine. Histamine causes your tiny capillaries to leak fluid. This is why bee stings cause itchy red spots. Histamine also contributes to some of the pain of the sting. Not all the proteins in bee venom cause pain. Finally, some good news, right? Wrong. Some ingredients help to strengthen the toxicity of the venom. Apamin, which makes up 3% of venom, destroys nerve tissue. Hyaluronidase (2% of venom,) helps the reaction to spread to surrounding tissue by breaking down one of the components of cell tissue.

It’s not just the chemicals in a bee’s venom that make it such an effective defensive weapon. Bees also have an excellent dispersal mechanism – their stings. Only female insects can sting, and scientists believe this is because the sting evolved from the insect’s egg-laying organ-the ovipositor. The structure of this modified ovipositor allows the sting to act like a self-guided missile. The bee doesn’t need much force to embed the sting into its victim the barbs are positioned on the sting in a way that helps pull it further into the wound. Attached to the sting is the bee’s venom sac, containing the bee’s chemical cocktail of mellitin, histamine and other proteins. When a bee stings, venom is released into a space on the sting between the barbs and the stylet. Honey bees won’t sting unless they sense a threat, because they can’t withdraw their stings. Once they sting, they die. The venom sac and sting of the bee are torn from the abdomen and left behind. Amazingly, even when the sting is no longer a part of the bee, it can keep pumping venom into a victim. That’s why getting the sting out quickly after a sting is important.

When a bee stings, an alarm pheromone is released by its Koschevnikov gland. Located near the sting shaft of the worker bee, this gland is responsible for most of the bee’s alarm pheromones. When worker bees detect this alarm pheromone blend, they fly faster and buzz more. It’s a bee home security system. It signals the defenders (aka stingers) to seek and sting threats. That’s why it’s a good idea to apply two or three puffs of smoke to the sting site after removing the sting to mask the tell tale alarm odor.

The alarm pheromones of honey bees contain about 20 compounds. Of these, isopentyl acetate is the key compound. Bees begin to produce this IAA (also known as isoamyl acetate), at about day 15. The production will peak at 2½ weeks. IAA has a very familiar smell, because it has the exact same chemical composition as banana oil. That’s why there’s a banana smell when bees sting another animal. Fortunately, smoke tends to mask the smell of this pheromone. This loss of signal results in just a few angry bees rather than a swarm of stingers ready to defend the colony.

Bee stings are one of the hazards of the beekeeping trade. They are inevitable, even when every precaution is taken, and researchers are working on ways to reduce the impact of the bee’s venom. Because the sting keeps pumping venom into the sting site, scientists are realizing that the method of removal isn’t nearly as important as getting the sting out-ASAP. In the past, the rule of thumb was to avoid pulling the barb out with fingers or tweezers. The thinking was that more venom would be squeezed in. Now scientists are advising speed over precision. Forget digging around in your wallet for a credit card to scrape it. Unless it’s handy, that wastes time. Studies have shown that leaving the stinger in just eight seconds can increase the size of a bee welt by 30%. It doesn’t really matter how you remove the sting just flick it off as fast as possible. Your hive tool is the perfect scraper, by the way.

Once a bee stings, your body chemistry begins to change to combat the toxins. Because your immune system considers the unknown proteins of bee venom to be invaders, it makes antibodies. The job of these antibodies is to strengthen the immune system against future attack. Unfortunately, some people develop an overly-sensitive immune response. In about 5% of the population, bee stings are much more than just painful – they’re life threatening. Two out of every 1000 people are at risk of anaphylaxis from bee stings. This inability to breathe can occur within seconds or minutes. Beekeepers who are prone to other allergies have a much greater risk of developing these severe allergic reactions to venom.

Most adults without known allergies can tolerate about 10 stings per pound of body weight. In the event of multiple stings, it’s a good idea to see a health care professional. That’s because your kidneys might need monitoring for a few weeks. When a sting occurs, cell tissue is damaged. The kidneys’ job is to eliminate this damaged tissue. In the case of multiple stings, however, there may be too much damaged cell tissue for the kidneys to process. This can cause the kidneys to clog and fail days after an extreme stinging event.

Reactions to bee venom are classified as systemic or localized. Systemtic reactions require immediate medical attention. Swelling in these reactions may occur in areas other than the sting site. Shortness of breath, dizziness and a drop in blood pressure can signal anaphylactic shock, which can result in death if not treated. The usual treatment for these allergic emergencies is epinephrine. This form of adrenaline slows the blood pressure drop by forcing the blood vessels to constrict. It improves breathing by relaxing the airways and also helps to reduce swelling and itching. Once an allergic reaction has occurred, it’s necessary to carry an Epi-Pen or sting kit at all times. Doctors also advise wearing a medical alert bracelet.

Most localized reactions to bee venom (except stings to the eye) can be treated at home. Swelling is normal in a bee sting and ice helps because it constricts the blood flow to the sting site by narrowing the blood vessels. Less blood flow means less swelling. A few topical ointments, such as calamine lotion, can also offer relief. Calamine lotion helps because its crystals are large and cause moisture on the surface of the skin to evaporate quickly. Much like an evaporative cooler, this rapid absorption of moisture helps the skin feel cooler. The histamines in bee venom that cause itching, swelling and pain can be blocked by certain medicines. The molecules in the cell membrane at the sting site are called receptors. Histamines “turn on” these receptors when bee venom invades tissue. Antihistamines, such as Benadryl, work because they keep these receptors from “turning on.” Thus, the capillaries don’t leak fluid and swelling is reduced. Pain relievers that contain aspirin should be avoided with bee stings. There’s already quite a bit of bleeding under the skin and aspirin makes it worse.

Even though the chemical compounds in bee venom can pack quite a punch for predators, those same compounds have the potential to be remarkably effective in medicine. Researchers have discovered that melittin is a strong anti-inflammatory agent. When venom in injected into the body, the melittin stimulates the production of cortisol, also known as the “fight or flight” hormone. In addition to giving the body an extra boost of glucose energy, cortisol also reduces inflammation. Scientists hope that the use of melittin will aid patients with diseases such as arthritis and MS, where inflammation can be debilitating. Melittin has also been shown in laboratory studies to slow the growth of certain cancer cells, such as melanoma and breast cancer.

When researching bee venom for medical purposes, scientists begin with dry bee venom. When exposed to air, venom dries into grayish-white crystals. These crystals are then converted into a powder form. The hope is that this powdered bee venom can be used to produce injectable venom for the treatment of certain diseases. Because it takes a whopping one million bee stings to collect just one gram of dry bee venom, it’s quite expensive. Scientists are developing an artificial form of melittin in order to further their research.

Bee venom is a complex substance, and laboratory research into its medical applications is relatively new. Although many people swear by at-home bee therapy, known as apitherapy to treat their MS and other conditions, science moves a bit more cautiously. Bee venom is a toxin, so a scientific approach to research and treatment must be taken. Even so, the hope is that bee venom may lead to medical breakthroughs for those suffering from debilitating inflammatory diseases. So, while bee venom might sometimes be a pain, it might also be a cure. Maybe the occasional “zap” isn’t such a bad trade-off after all.

Abdu, Mahmoud Al-Samie and Mohamed Ali. Studies on Bee Venom and Its Medical Uses. International Journal of Advancements in Research & Technology, Volume 1, Issue 2, July 2012.

About Honeybees. University of Arkansas: Division of Agriculture Cooperative Extension Service. April 2016.

Bee Stings. United States Department of Agriculture. Agricultural Research Service. April 2016.

Breed, Michael D., Ernesto Guzman-Nova, and Greg J. Hunt. Defensive Behavior of Honey Bees: Organization, Genetics, and Comparisons with Other Bees. Annual Review of Entomology. 2004. 49:271-98.

Caron, Dewey M. Honey Bee Pheromones. Lewis County Beekeepers. April 2016.

Communication: Basic Bee Biology for Beekeepers. Bee Health: Extension.org July 2009.

Dockterman, Eliana. Scientists Think Bee Venom Could Fight Cancer. Time.com (2014): 1.

Hunt, G.J. Flight and Fight: A Comparative View of the Neurophysiology and Genetics of Honey Bee Defensive Behavior. Journal of Insect Physiology 53 (2007) 399-410.

Kaplan, Alan. Once Stung, Twice Shy. Bay Nature 8.3 (2008): 44-45.

Loveridge, Joel. Bee Stings. University of Bristol School of Chemistry. April 2016.

Morse, Roger, and Brenda Bull. Insects that Sting. Conservationist 49.6 (1995): 22.

Murdoch, Guy. Sting Treatment. Consumers’ Research Magazine 80.6 (1997): 2.

Wright, Russell, Phil Mulder and Hal Reed. Honey Bees, Bumble Bees, Carpenter Bees, and Sweat Bees. Oklahoma Cooperative Extension Service Fact Sheet EPP-7317. April 2016.


Shimmering to Safety

It might not make sense to us for an animal to build its home in the open when there are other, safer options. But giant honeybees are the second oldest known bee species. So they must be doing something right. Overall, this shimmering behavior shows that the giant honeybee has developed several different strategies to scare off predators while avoiding an attack.

Additional images via Wikimedia Commons. Honeybee image by Fir0002. Vespa hornet image by Gideon Pisanty. Video of shimmering behavior taken from the PLOS article supplementary information.


Why don't bees sting hornets for defense? - Biology

The prospect of death by giant hornet has pushed some Asian honeybees to resort to a poop-based defense system

Full Transcript

&ldquoThey&rsquoll basically crush or pop the head off of any worker who tries to attack them.&rdquo

If you&rsquore a honey bee, a hornet attack could be the last thing you ever experience. It&rsquos a gory, violent process. And honeybees have had to adapt to stay alive.

You&rsquove probably heard of the &ldquomurder hornets&rdquo that recently turned up in North America. This is not a story about those. This research takes us east to meet their cousins.

Wellesley College biologist Heather Mattila went to Vietnam to understand how Asian honeybees defend themselves from the hornets there.

&ldquoAnd in Vietnam, that&rsquos the giant hornet Vespa soror.&rdquo

Typically, when a hornet invades an Asian honeybee hive, hundreds of bees surround the intruder and create what&rsquos called a heat ball. With the hornet caught in the center, the heat goes up, and the oxygen goes down. The bees literally cook and choke the hornet to death.

But Vespa soror has figured out a way to avoid this trap.

&ldquoGiant hornets will hunt honeybees on their own and grab them one by one. But what is really lethal to honeybees is when they flip into a multiple hornet attack strategy. And when they do this, they essentially want to kill all the adult defenders so that the colony is no longer protected.​​&rdquo

But in the face of this deadly bum-rush, Asian honeybees have resorted to the scatological.

&ldquoA lot of the beekeepers hadn&rsquot noticed them. Or if they had, they didn&rsquot know what they were. But there was a handful of beekeepers who had seen these spots.&rdquo

Those spots, it turned out, were poop.

The hive mind&rsquos decision to dip into the dung pile didn&rsquot come lightly, though. The alternative to covering their house in .

. was annihilation of the colony in the face of overwhelming giant hornet invasion.

&ldquoAt a certain point, the workers in the colony decide it&rsquos a lost cause, and they&rsquoll abandon ship, and everyone leaves. And that leaves the entire colony undefended. So at that point, the hornets can successfully, without any interference, break into the nest and occupy it. And when they take over a nest, what they do is ferry the bee larvae inside back to their own hornet larvae so that they can eat them.&rdquo

One beekeeper told Mattila and her colleagues that he had seen the honeybees collecting bits of water buffalo dung. He thought that might explain the spots. He thought the bees might be using dung to keep the hornets away.

&ldquoWe confirmed that bees actually forage on dung, which is a surprise in itself.&rdquo

Honeybees generally keep their nests clean and tidy. They&rsquore good at keeping diseases and pathogens out&mdashtwo things that could be hiding in animal poop.

&ldquoThe thought of them collecting feces in the field and intentionally bringing it back home was pretty stunning.&rdquo

Whenever they detected a giant hornet nearby&mdashbut not other, smaller hornets&mdashthe honey bees began to arrange bits of mammal or bird dung near the entrances to their hives. And the hornets themselves were less likely to land on a nest adorned with poop. If they did bother to land, they spent 94 percent less time attempting to break in. The study was published in the December 9 issue of the journal PLOS ONE. [Heather R. Mattila et al., Honey bees (Apis cerana) use animal feces as a tool to defend colonies against group attack by giant hornets (Vespa soror)]

The researchers say this is the first time honeybees have ever been documented collecting nonplant matter. And because the bees are selective in what kind of poop they collect and use it in a very specific way, they say it actually qualifies as tool use&mdashthe first known instance in wild bees.

It isn&rsquot clear why or how the poop shield works, but Mattila suspects that there must be some chemical inside the poop&mdashpresumably derived from the plants that the animals originally ate&mdashthat either actively repels the hornets or camouflages the scent of the bees&rsquo nests.

American bees don&rsquot do this. Asian honeybees are a different species than the Western honeybees in Europe and North America.

&ldquoI just can&rsquot even totally capture how much fun it really was to do this work. I didn&rsquot have a lot of personal experience with Asian bees, and so meeting them was kind of like meeting the crazy cousin of the bees you know really well. These bees are a lot smaller, but they&rsquore very, very fast and very reactive. And that&rsquos because of the kind of hornet pressure that they&rsquove evolved under. They have evolved to fly quite quickly in zigzagging patterns as they&rsquore approaching their nest so that they&rsquore very hard to catch.&rdquo

Western honeybees did not evolve alongside hornets, as did their Asian cousins, which makes them especially susceptible to hornet attacks in places where giant hornets become introduced. If Mattila and her team can figure out how poop keeps hornets away, it might help North American beekeepers help their bees to survive&mdashif the so-called murder hornets decide they like it here.

[The above text is a transcript of this podcast.]

ABOUT THE AUTHOR(S)

Jason G. Goldman is a science journalist based in Los Angeles. He has written about animal behavior, wildlife biology, conservation, and ecology for Scientific American, Los Angeles magazine, the Washington Post, the Guardian, the BBC, Conservation magazine, and elsewhere. He contributes to Scientific American's "60-Second Science" podcast, and is co-editor of Science Blogging: The Essential Guide (Yale University Press). He enjoys sharing his wildlife knowledge on television and on the radio, and often speaks to the public about wildlife and science communication.


Honey bees in Vietnam have a surprising defense against murder hornets

Murder hornets earned the accolade of the Internet's most feared insect in 2020, and for good reason. These beastly creatures can grow up to two inches long and reports recount how they brutally decapitate bees with such ferocity as to wipe out entire colonies in a matter of hours.

But nature is resilient. In new research published in the journal PLOS ONE, researchers reveal how the Asian honey bee employs a surprising, smelly solution to deter the fearsome Asian giant hornet: poop.

What's new — The researchers observed bees deploying a defensive tactic they call "fecal spotting," in which the honey bees scout for nearby animal dung, and then apply it to the entrance of their hives in response to a hornet attack.

Beyond dung, the researchers observed the bees picking up other smelly defensive tools.

"The Asian honey bees we studied collected other substances in addition to dung. In one instance, a hive showing all of the 'spotting behaviors' reeked of urine, and I found the bees drinking urine to apply to the hive front," Gard Otis, University of Guelph professor and co-author on the study, tells Inverse.

Curiously, Otis and his colleagues did not spot fecal spotting in attacks against other types of insect predators, suggesting perhaps that there is something unique to the way giant hornets react to animal dung.

"We speculate that dung contain compounds inherently repellent to hornets or that it simply masks bee odors," Otis says.

By comparing bee colonies that had been visited by hornets and those that had not, researchers saw a clear correlation between fecal spotting and hornet attacks. As the study states:

How they did it — Otis and his colleagues spent more than two months watching bee colonies in Vietnam, examining how honey bees responded to attacking murder hornets.

In their short time, the researchers recorded a whopping 276 hornets visits to these bee hives on camera.

They also set up a control colony to ensure that they had a test group the hornets would not visit. To achieve this, the researchers stood near the control hive and waved plastic bags tied to sticks to frighten away the hornets.

What we don't know — Despite the clear success of the honey bee's smelly strategy, it's not clear why dung thwarts hornets but not bees.

"Because we don't know what the bees are seeking in feces, we can't say at this point why it repels hornets but is acceptable to the bees. The fact that this is the case, however, is very interesting," Heather Mattila, lead author on the study and associate professor of Biological Sciences at Wellesley College, tells Inverse.

It's also worth noting that feces are not the Asian honey bee's only line of defense against these hornets, or other types of hornets.

In fact, these honey bees have effectively adapted to "a suite of defensive strategies" to defend their colonies from all manner of invaders — including a terrifying technique where they form hotter and hotter balls to cook the murder hornet alive, Mattila says.

"We have no idea about the relative importance of the defensive behaviors of Asian honey bees in preventing attacks by hornets," Oris agrees. "I would not say that hive spotting is more or less effective as a defense."

It's also unclear whether fecal spotting is always an advantageous battle tactic, as it may interfere with the bee hive's goal of quickly banding together its workers to defend against a mass hornet attack.

"It may be that hive spotting interferes with the recruitment of nestmates observed during the mass-attack phase of giant hornets," Otis says. "Some of our data indicate that when hives have been heavily spotted, the hornets less frequently switch from catching single bees to mass-attack."

Why it matters — Human beekeepers could stand to learn something from the honey bees' smelly strategy, using feces to protect their hives from hornet invasions. But, the researchers are skeptical. There's still too much that we don't understand about this defensive strategy.

"If we understood more about what bees are seeking in feces to protect their homes, then we could envision the possibility of humans applying that repellent to colonies in a safer manner," Mattila says.

"I think the optics of doing that for honey customers could be very bad," Otis adds.

Instead, Otis suggested to a colleague in Vietnam that he try applying essential oils to bee colonies.

"He set up a nice experiment, but he failed to detect differences between treated and control colonies," Otis says. "However, the hornets stopped visiting the apiary, so perhaps the strong odors drifted throughout the area and acted as a general repellent to the hornets."

What's next — A different variety of murder hornet (Vespa mandarinia) has now made its way to North America, where the honey bees are unfamiliar with their deadly behavior. The reports of murder hornets in the Pacific Northwest have prompted concerns they could wipe out local bee colonies and terrify humans in these areas, who fear these hornets' painful sting.

Lacking the evolutionary knowledge of their Asian counterparts, bee colonies in the United States will be highly susceptible to the murder hornet's vicious takeovers.

"We have not seen how our Apis mellifera honey bees in North America might react to smelly substances placed at their hive entrance, given that they lack defenses against hornets that we see in Apis cerana of Asia," Otis says.

If murder hornets do became a frequent presence in North America, we'll need to explore any means possible to take them down. Including poop, potentially. There is still time, however.

"At this point in time in North America, Vespa mandarinia is still exceedingly rare," Otis says.

"If that species — or Vespa soror — do become established in North America, researchers and beekeepers will need to explore repellents, hornet traps, hornet excluders, etc. that would need to be incorporated into hive management, Otis says.


Honey Bees Use Animal Dung to Fend Off Giant “Murder” Hornets

What’s the best way to ward off giant hornets if you’re a honeybee? Animal dung, according to a first-ever University of Guelph study.

U of G researchers have discovered honeybees in Vietnam collect and apply spots of animal dung around hive entrances to deter deadly nest raids by an Asian hornet (Vespa soror) whose North American cousins have been dubbed “murder hornets.”

This finding is also the first to document the use of tools by honeybees.

An invasive species in North America that came originally from Asia, giant hornets are almost as long as a golf tee and pack about seven times as much venom in a single sting as an ordinary honeybee.

Murder hornets (V. mandarinia) were discovered in 2019 in British Columbia and Washington. The arrival of the venomous insect to North America has raised concerns about human safety as well as threats to local honeybees and ecosystems.

U of G Prof. Gard Otis, who has studied honeybees in Vietnam for decades, said the hornets could ultimately carry out similar honeybee hive raids in North America.

“Giant hornets are the biggest wasps that threaten honeybees. They are one of their most significant predators,” said the environmental sciences professor.

Otis conducted the study with lead author Heather Mattila, who completed her PhD at the University of Guelph in 2006 and is now a biology professor at Wellesley College in Massachusetts. Other co-authors were former U of G grad students Hanh Pham and Olivia Knight, as well as Ngoc Pham and Lien Nguyen in Vietnam.

Published recently in the journal PLOS ONE, the study was conducted in Vietnam, where U of G researchers studied V. soror.

Honey bee carrying dung in its mouth. Credit: Heather Mattila

These two species are the only hornets that recruit nestmates in organized attacks that can lead to nest breaches, said Otis. The hornets raid the nests, killing the bees and carrying away larvae and pupae to feed their own developing brood.

The researchers found that honeybees have developed a pre-emptive defense by collecting animal dung and applying it to hive entrances.

“This study demonstrates a fairly remarkable trait these bees have to defend themselves against a really awful predator,” said Mattila.

She said unlike their Asian counterparts, honeybees in Canada lack similar defenses. That means North American beekeepers would have to rely on destroying the hornets’ nests, or hope that climate or other factors will limit the hornets’ spread.

Referring to Apis mellifera, the honeybee species commonly found in Canada, Mattila said, “They haven’t had the opportunity to evolve defenses. It’s like going into a war cold.”

Otis began the project after asking beekeepers in Vietnam about dark spots at hive entrances of Asian honeybees. As part of a successful beekeeping development project funded by the Canadian government, he ran fall workshops from 2007 to 2011 in rural villages with high levels of poverty.

During one visit, an experienced beekeeper explained that the substance was buffalo dung. All the beekeepers that Otis worked with linked these hive spots with hornets. “Dung collection is a behavior never previously reported for honeybees, and no one had studied the phenomenon,” he said.

In 2013, the U of G team received US$25,000 from the National Geographic Society for the study.

Giant hornets at the entrance of a hive without dung. Credit: Heather Mattila

The researchers gathered dung from water buffalo, chickens, pigs and cows, and placed it in mounds near an apiary. By the end of the day, some 150 bees had visited the piles, particularly collecting more odoriferous manure of pigs and chickens.

The team marked individual bees to identify them at their hives. Minutes later, they recorded videos of the marked bees applying the material at nest entrances.

The hornets spent less than half as much time at nest entrances with moderate to heavy dung spotting as they did at hives with few spots, and they spent only one-tenth as much time chewing at the hive entrances to get at the bees’ brood. They were also less likely to launch mass attacks on the more heavily spotted hives.

The researchers are unsure just what deters the hornets, although they suspect the insects are repelled by the smell of the dung. Dung may also mask odors emitted by the bees.

To further understand the hornets’ behaviors, the researchers extracted the chemical pheromone applied by hornets when marking their target hive. When the pheromone was applied to the bees’ entrance, it prompted honeybees to apply dung to the hive.

Many scientists disagree over whether certain animals — let alone insects — use tools.

To qualify as tool users, animals must meet several criteria, including using an object from the environment — in this case, dung. The bees clearly use the material to alter the hive with purpose, said Otis. And they shape and mold it with their mouth parts, which he said meets the test of holding or manipulating a tool.

Beekeepers in Vietnam normally control hornets by standing guard and swatting away individuals, preventing them from escalating their attacks.

“If you allow them, a group of hornets assembles, attacks the colony and takes over. The beekeepers control them every day by moving among their hives and whacking hornets.”

Otis said he was terrified at first about working near the giant hornets. The hazmat suits typically worn for protection by researchers in Japan were impracticable in Vietnamese heat, he added. Within a few days, the team learned the hornets were not defensive when they were in the apiary and away from their own nest.

“I got stung by one and it was the most excruciating sting in my life.”


Asian honeybees �nd hives from hornets with faeces'

They say the finding is the first to document the use of "tools" by honeybees.

The bees used chicken poo, buffalo dung and even human urine to defend their hives.

Honeybees play a critical role in pollinating the plants humans depend on for their diet.

The scientists behind the study, published in the journal PLOSE ONE on Wednesday, said the research was sparked when a Vietnamese beekeeper told them that the mysterious dark spots they had spotted at hive entrances was excrement.

"We thought thatɽ be crazy because bees don't collect dung," lead author Heather Mattila told AFP news agency.

But the study confirmed that the poo was indeed a defence being deployed by the bees, specifically against giant hornets.

It adds to "an already impressive list of defences they have to prevent these hornets from destroying their colonies", Dr Mattila, a biology professor at Wellesley College in the US state of Massachusetts, said.

Bees are known for using a range of strategies to deflect attacks from predators.

They have been observed physically shielding their colonies through synchronised body shakes, hissing, or enveloping encroachers in a ball until they overheat.

Giant Asian hornets - up to five times bigger than honey bees - can slaughter a bee colony in a matter of hours. They can also inflict powerful stings on humans.

The scientists found that the hornets were less likely to launch mass attacks on hives dotted with more faeces, and that they spent 94% less time chewing at the entrance if they did land.

The use of excrement was particular to Asian honeybees, they added, saying their counterparts in Europe and North America lacked similar defences.

Asian hornets have recently been detected in North America where they have been dubbed "murder hornets" for the threat they pose to local honeybees and ecosystems as well as concerns about human safety.

Around 40 people are killed annually by the hornets in Asia, according to the Smithsonian Museum in Washington DC.