Bee Science with Dewey Caron - Listening to the Bees

Listening to the Bees

Dr. Dewey Caron

Hi, I'm Dr. Dewey Caron. I come to you from Cochabamba, Bolivia, where we are just beginning spring. I present another audio postcard in my once-monthly Beekeeping Today miniseries podcast, Bee Science with Dr. Dewey Caron. This is the eighth installment in this series. In each episode, I seek to blend research, field experience, and seasonal context, focusing on the why behind honey bee biology and behavior. I welcome your suggestions for timely topics. I'll start with a question. Do you use all your senses when you are in a beehive? We certainly depend on what we are seeing, and to a lesser degree what we are feeling, being at a sting or weight of frames that we are removing.

Plus, with a bit of training, we can smell a colony that is having trouble, maybe with honey fermentation or certain diseases. AFB comes to mind, but disease often has a sour smell And I submit, I enjoy the normal, pleasant, smelly mixture of beeswax, honey, and bees. But what about sound? Are you listening to your bees? Me and McNeil, in a 2016 two-part series on sounds, in the American Bee Journal, says, and I quote, Bees live in a world of sound that goes beyond our range. just as bees see ultraviolet light invisible to humans. End quote. We recognize there is a constant hum or buzz in a beehive.

What does it mean to you? Long time ago I participated in removal of a cutout from the wall of a frame house outside of Ithaca, New York. The actual hive was positioned between roughly twenty four inch space two by fours. Almost from rooftop to the stone foundation. It was a one-story wooden building. It was on a bedroom side of that building. We were lucky as the weathered wooden siding was vertical, not horizontal. We could remove several boards to fully expose what was a huge nest. was a learning experience in cut out removal of a nest, my first experience.

We filled buckets with honey, cut brood comb to make three colonies, and by at the end closed up the cavity as best we could to help prevent re-invasion by another swarm.

Three days later, we got a call from the homeowner. He was an older gentleman living alone. Expecting a thank you, we instead were surprised. He wanted us to bring back the bees. Why? Well, because he couldn't sleep It turns out the bee hum was his evening comfort. He was missing, listening to that bee buzz, before he fell asleep. Alas, we couldn't accommodate him Forward to present.

This season my fifty year old son started his own colony, having helped me many, many times with care of my own hobbyist colonies, that are now under the care of my forty year old eight year old daughter. Visiting in July to determine if the bees were collecting enough honey as we were nearing or at the annual seasonal drought, I noted a long chair adjacent to the hive I asked if he was watching the bee entrance. He said yes. They like to take his work breaks, he works from home, and just sit and look and listen to the hive. and take in the odor of the hive.

It took this comment for me to validate one of the pure joys of my sixty-five beekeeping years Entrance activity, and the hum of a contented colony. This Bee Science explores sound in the colony As a teaser, I will do this as a two-parter, but not back to back.

There's so much we are learning about sound in bees I will cover how bees make and listen to sound, the hum of the hive, and also return to the dance language sound component As this was the first bee behavior for which researchers showed that sound is indeed a powerful communicating tool in our understanding bees and in the bees' arsenal. The sounds bees make and listen to, in addition to being a valued communication means, are, I submit, one of the benefits of being a beekeeper. All of you have, perhaps one time or another, enjoyed and marveled over the buzz of bees.

Are you aware that more Experienced beekeepers are able to recognize what is happening inside the colony simply by listening to the sounds emitted? Some at least can. And to support modern techies. Companies are building the machinery and support systems to capture bee sounds, to help us understand what is happening in our hive, and reduce unnecessary that's their words.

Hive inspections. Turns out recognition that bee sounds might mean something goes back to antiquity. Aristotle in the third century BC documented the first observation of bee sounds, noting a continuous, distinct, acoustic signal produced by hives several days before swarming Could he have heard piping? Oh more on this sound that he might have heard, but he'll have to wait until part two. So good beginning here for part one is How do bees make sound and hear it? The basic sound bees make is produced by rapid wing movement. or of vibrating by the flight muscles, the muscles that will move the wings. This movement creates sound waves in the air.

As we listen, we can hear a background buzzing noise made by a colony with its thousands of workers. Occasionally it may be a higher pitch. Angry buzz, or that is our interpretation at least The higher-pitched hum is believed to serve as a warning sign to predators or intruders to back away from the nest The normal humming sound is around 190 Hz to 250 Hz. Hertz is the International System of Units of Frequency Often described as being equivalent to one event or one cycle per second. The disturbance resonance spikes past 500 Hz to as high as 300, 3,000 hertz plus with loud buzzing. But does that mean the basic hum or buzz noise is one of contentment We interpret as such.

We do not really know. Is it communication of some sort? Again, we do not really know. I love this quote from Adrian Winter. As everyone knows, the bee is a rather noisy animal. Even its buzz in flight, however, is not just noise. The buzz has modulations and variation. We do know bees like to be crowded, and they routinely produce this basic buzzing or humming sound as they go about their business in their dark, smelly, humid hive. Does the basic buzz signify contentment?

The SOP? They're signaling all is okay We need a bright young university student to figure this out. But inside the hive, bees do not usually move their wings. Instead, the bee's flight muscles flex its thoracic walls, since that is how the flight muscles are anchored internally inside the bee's exoskeleton. Not to the wing itself. The bee's body acts as a resounding board, amplifying those vibrations into a constant low-level noise or hub. In-and-out motion of the flight muscles pushes against the air to create an audible tone. A faster wing muscle movement makes a higher pitch Perhaps the higher pitched sounds may also include opening and flexing of wings.

But in a crowded hive, flexing wings might damage them unnecessarily, so they flex the muscles, not the wings, per se and this produces the sound. Why do they move these muscles? We know one reason for movement of the opposing wing muscle groups is that it is a means of generating heat. Bees may also move the flight muscles to ensure readiness in case flight becomes necessary. And it could also serve as a basic communication, that colony hum. A queenless colony, as we are, are often aware, has a different sound from one that is queenright. When a bee family is orphaned without a queen bee, the buzz is louder and prolonged. We describe it as a whining-like sound or roar.

It is most evident when we open the colony, but will then continue as we do our an inspection.

Oregon queen breeder John Jacobs, with lots of experience, says, quote, When you open splits, you know which unit has the queen and which ones don't, based on sound alone. End quote. Diana Sammataro, retired Ohio and USDA researcher, now living in Tucson, Arizona, says, quote, the decibel level is above sixty-five if the bees are queenless The bees are more agitated and more runny, but a hive can also sound similar if they have been disturbed by an animal. End quote. These quotes, by the way, are from the two-part article on bee sounds by Mia McNeil in the American Bee Journal. They have references supplied in the end notes.

Next season, see if you can use sound to initially diagnose, using the whining or roar from a colony, so that you can diagnose queenlessness, maybe even this season Examine the hive, of course, to verify that it is queenless, if you hear this change in sound.

Start getting used to listening to bees. Sound is a vibration. It causes molecules to pulse outward, colliding with nearby molecules, creating waves. As you might guess, bees and humans hear slightly differently. Humans hear by detecting the resulting oscillations in air pressure. as the waves vibrate our inner ear eardrum, sending information to our brain via nerves where it's interpreted. Bees hear slightly differently in that they are detecting air particle movement Because traveling sound waves have both components, that is, both the molecule waves and air movement, either can be used in sound perception by animals. In the last Bee Science, released mid-July, I covered how bees communicate with dance language. When Dr. Karl von Frisch of Germany first described the waggle dance.

He did not include experiments on sound emission during bee dancing. He concluded the distance component of a waggle dance was the time for a completed cycle of waggling. That is the waggling, then the right turns, set waggling, and then the left turn. That was what he interpreted as a information for distance. Then in the early 1960s, two researchers independently discovered that dancers emit low frequency sounds. Adrienne Wener of UC Santa Barbara, whom I quoted above, and Harald Esch at the University of Munich.

Both researchers demonstrated that dancing bees produced low frequency sound pulses, roughly that two hundred to three hundred hertz range, that we would classify, really, in our ears a musical key of C Via wing muscle movements during that straight portion of the waggle dance. Initially, their assertion that the bees use sound to communicate was widely questioned The community, those that had looked at bees, bee scientists, etc., accepted the belief that the bees had no ears and they could not hear sounds Subsequently, we now believe that only by timing sound production during that just the waggling section of the waggle dance itself Are bees able to precisely communicate to recruits, to their sisters, flight distance to the food source?

Longer sound production means a greater distance to fly. We now also understand that bees are picking up airborne sounds. The definite study on the bees' ability to hear air particle movement is that of William Towne and Wolfgang Kirchner. They demonstrated that honey bees can detect airborne sound by sensing air particle movement with their antenna. They found that dancing bees emit a buzzing sound produced by the wing beats at a low frequency of 250 to 300 Hz. With a pulse duration of about 20 milliseconds and a repetition frequency of about 30 per second The specialized Johnston's organ in their antenna detects, at close range, the acoustic signals during that waggling dance.

and likely other airborne sounds, such as the hum of the beehive. The Johnston's organ is located at the base of the bee's antenna. Tiny sensory hairs called sensilla sense airborne vibrations by detecting how sound waves cause the antenna to move.

With over 300 nerves, Johnston's organ converts these vibrations into nerve impulses, which are then sent to the brain for processing. Unfortunately, that Town Kirchner publication published in Science is Behind a Firewall, and not readily available for us to look at Alternately, sound vibrations can be transmitted by substrate, such as when we crack the lid of a hive, which creates a roaring, rumbling surge of vibration. or when we jar the hive, intentionally or not, in our hive inspections. In the waggle dance, waggle dancers on combs with open empty cells, Recruit three times as many nestmates to a food source as dancers on capped brood cells due to improved transfer of vibrations for those recruits to detect those vibrations.

We also know uneven combs and those with cap brood cells make it more difficult to correctly recruit followers because they have issues to pick up those vibrations through the comb. Comb built from plastic foundation does not seem to decrease information transfer. The subgenual organ located in the tibia femoral leg joint is how the vibration is detected We know beekeeper caused vibrations result in a different sound for the bees, which alerts soldiers, some of which fly out of the open hive to investigate the source of the disturbance.

The response might be a good reason that bees might want to keep their body temperatures warm enough for flight, so there are reasons to use those wing muscles. But as it turns out, bees can sense both vibration and airborne air particles and tandem in sound communication. We call this combination vibroacoustic signals This is a word that combines both vibration and sound waves acoustic. This kind of signal captures the combined effects for potential recruits. Those both close to the dancer can listen to airborne sound, and bees not as close can pick up the distance information by the vibratory motion that's transmitted via the cone. So recruits do not need to be immediately close to a dancer.

Before I leave Be Dancing, I recommend you listen to a YouTube. Something that I don't normally recommend, or at least not on a regular basis. This is a broadcast by Dr. James Nieh of UC San Diego.

Dr. Nieheh has been working on building a sensor to optically measure sounds generated by bee-wing vibrations. This could solve the problem of sound recording and tracking in the noisy hive environment. Instead of a microphone, his new detector measures reflected red light. which is largely invisible to bees but can easily be seen by the researcher. Using a 3D printer, he has built a waggle dance sound Simulator. Hmm, that's cool stuff. This particular YouTube broadcaster, Dr.

Nieheh's presentation, discusses how sound is used as a stop signal that bees use to halt dancing when there is high competition at the foraging site, or to use against scout seeking to tell a swarm bivouac that is that swarm hanging in a tree, of alternate sites that are not as good as the site that particular scout has found.

So as to halt dancing about poor alternatives so the swarm cluster can make a better decision on where to move He features Dr. Nieheh features and references work of his lab. His studies that include European bees as well as other honey bee species in Asia and stingless bees in America uses the centered scented sugar water feeder technique of von Frisch, favored for this type of research, and recording via microphone, not his new detector. Going to be interesting to see as he uses his new detector for continuing studies. The video also discusses how bees use wingbeat frequency sound as a I-see-you signal

This signal to hive mates for predators such as hawking wasps. Guard bees or forager bees clustered at the entrance do this flicking of their wings, a wave-like motion. We see it as a wave-like motion as the wasp moves closer to the entrance. Then these experiments, Dr. Nieh has used a flying wasp glued to a wire that he maneuvers close to or just in front of the entrance. Dr. Nieheh presents information to show this wing flicking, dampening any flight from the hive, avoiding would-be foragers being captured by that enemy, the wasp. Hawking behavior is how Vespa velutina, which is the one that he is using, that species, the yellow-legged hornet, which accidentally entered the southeastern U. S. captures bees.

It hawks him right from the air before the colony entrance. If that's not good enough to entice you to view the YouTube as a third portion of his research... Dr. Nieh discusses how bees have evolved by learning so they become more accurate in passing specific information during the waggling sound and the gravity angle too during their bee dancing One neat finding, a really unique experiment. He has Naive Bees dancing for the very first time that have not had an opportunity to follow any dancers before their very first dance.

Provide distance information by the sound component that is too far than the actual distance And even after further dancing, they continue to give incorrect, too far a distance, sound information, their entire lives of dancing.

If they have a chance to practice, and another part of the experiment, that is listen by following dancers before becoming a dancer themselves, before their very first dance, then they do not make this mistake. And although they are erratic at first, they do correct their directional information in subsequent dancing, improving the accuracy of this component of the information transfer but they don't correct the inaccurate distance information. Sound is also used in a round dance, although it is not used to convey distance to floral source, since a round dance does not include a waggling segment. Sound made by the round dancer is thought to serve as a stimulus to go get the food.

In the same way the odor of the visited source clings to the body of the dancing bee It is a mechanism to call attention to oneself. The dancer is used to stimulate recruits to leave and collect food. Food's available outside. Listen to me Close by.

Listen. Go get it. So they said my last bee Science, the one on dance language. Dance language is fascinating stuff. But let's go on to other, we'll go on to other sound communication. I'm going to do that in the next one Talk about some very special ones. One other aspect that Dr. Nieheh has looked at as well, as I said, he looked at different he's looked at different species. You can say that the movement of bees producing a special sound at the entrance are apparently warning hive mates of danger.

Due to the presence of that hawking wasp is holding on that wire in front of the hive entrance But we also see that in the single comb honey bees of Asia. These are the Apis dorsata and Apis florea groups. Dr. Nieh, through collaborators in Hunan, China, suggests these two honey bee species warn away predators that approach their nests by a rustling sound of their wings. This passes as we look at the nest as a wave among the bees of the enclosing envelope, the outside mantle of bees, of their single comb nest. These are single comb nest builders It is audible and am very impressive to see.

Our interpretation is that it means is a means of a signal to the nest inhabitants to prepare to do battle. and a warning to the would be nest predator to back off or be subject to attack.

Apis fluoria, according to Doctor Nee, has a painful sting, and anyone stung by the bigger bodied Apis dorsata Knows what a wallop that their sting packs. Sound within and without the species We know there are chemical pheromones that are meant not just for the bees, but also for their enemies. It appears that sound and wave from this wave movement of the wing flicking do the same As a teaser for part two on sound, I finished this part one on sound with the story of the Woods Apidictor. In the late 1950s, British beekeeper and BBC sound engineer Eddie Woods demonstrated that honey bee swarming could be predicted by listening for a specific acoustic modulation, around 250 Hz.

which he termed a warble, which indicated a colony was preparing to swarm. And he could detect this up to three weeks before actual swarming.

The invention was based on the premise that honey bees change their vocalizations depending on the health and state of the hive. Woods used electronic bandpass filters to isolate two distinct sound markers. Based on his research, he patented and offered to for sale his Woods Apidictor. Often incorrectly labeled Api Predictor. It was Apa Apidictor. He built 300 units And I happened to purchase one of the last of the those about ten years later while I was studying swarming for my PhD at Cornell. Woods' Apidictor never achieved commercial success as his algorithms were very awkward and left a lot to interpretation.

However, in retrospect, his research has been labeled, very importantly, as setting the foundation for modern precision beekeeping Today, automated smart hive monitors utilize digital sound processors, microphones, very sophisticated microphones, and machine learning algorithms to continuously track These exact frequency ranges, alerting beekeepers of swarming behavior, queenlessness, varroa infestations, and even other hive occurrences Amazing how this has developed.

And of course, it's all sent directly to your smartphone, so you've got to stay connected. And as a PostScript, another British beekeeper and former sound engineer, Hugh Evans has developed a whole monitoring system sold by the company established Arnia that updates the Apidictor using modern digital sound processors and now better algorithms designed to recognize different hums. He says, quote, every job a bee does inside a hive makes a slightly different noise. So if we can listen to the mass of sound within the hive and possibly dissect that We can find out a lot about the inner dynamics within the hive.

He continues, we started off looking for swarm prediction But when we began trolling enough through the data, we noticed some other features. The monitor can give an indication of the strength of the hive, the fitness of the hive How fast a hive is building, their intent to swarm in other such things.

What advances await us in the next couple of decades by measuring and interpreting the sounds that bees make to communicate? What further bee secrets can be revealed by understanding the sound bees make and by listening to them. Will it enable us to become better informed beekeepers? In part two, I will dissect some of the sounds bees make at swarming And hive communication. Till next time, be well