Most people know that cows “moo”, cats
“meow” and bees “buzz”, but few people other than beekeepers and apiologists
(the fancy word for honeybee scientists) know that bees also “quack”, “toot”,
and “beep”. In the Bee Lab, we are interested in social insect behavior,
including how they communicate with each other. Honeybees usually live in dark
hives in tree cavities, so they can’t use visual cues to communicate in the
hive. Instead, they communicate chemically through hormones called pheromones,
physically through the waggle dance, or vibrationally and acoustically through
the sounds they make.
You are probably familiar with the buzzing sound bees make as they fly around. That sound is caused by fast vibrations from their wings. Other sounds that bees make—usually called piping—are also caused by vibrations of their flight muscles.
You are probably familiar with the buzzing sound bees make as they fly around. That sound is caused by fast vibrations from their wings. Other sounds that bees make—usually called piping—are also caused by vibrations of their flight muscles.
Image 1: Bees beat their wings about 200 times a second, creating a buzzing sound.
Two of the most distinct forms of
piping are made by virgin queen honeybees. When a new queen emerges from the
nest, she “toots” by pressing her thorax against a comb and moving her flight
muscles. While she toots, all the other worker bees in the hive freeze,
probably to minimize any disturbance to her signal (you can see this in the
video below). Her signal is aimed at other queens that may still be in their
cells. If there are queens who haven’t emerged, they respond with higher-pitched
“quacks” which essentially tell the new queen that she has competition.
Video 1: Piping virgin queen bee
Now the queen is faced with a choice:
she can either swarm to avoid competition with the other queens or stay and be
prepared to defend her reign. If she swarms, she leaves the nest with a portion
of the worker bees and has to find a new nest and rebuild the colony. The colony
may be too weak from previous swarms for this to be possible. If she stays, she
has to quickly locate the other queens through their quacks, bite small holes
in their cells, and sting them to death before they emerge. Otherwise, she will
have to fight to the death with new queens that come out of their cells. After
all, there can only be one queen bee.
Workers also use piping to
communicate, but thankfully for less deadly outcomes. In one type of worker
piping, nest-site scouts run through a group of bees getting ready to swarm and
emit pipes that tell the other bees to warm their bodies to get ready for
lift-off. Apiologists have noticed another type of piping—called a “beep” or a
“whoop”—that is very short and soft in contrast to the longer and louder “toots”
and “quacks” of virgin queens, but the functions of these sounds are still
being debated.
When this shorter sound was first
discovered, it was described as a “begging signal” because people thought that
worker bees used it to ask for trophallaxis—a mouth-to-mouth transfer of
regurgitated food—from forager bees. Later, some studies suggested that it
could be used to signal danger, specifically used by forager bees after they
experienced a predator or other threats at a foraging site. Other studies described it as a “stop signal”
for waggle-dancers. As scout bees do their waggle-dance,
other bees can head-butt a dancer and make a soft “beep” to voice their
complaint if they don’t agree with the nest or foraging site she’s advertising.
After multiple head-butts, the criticized scout bee eventually stops dancing
and gets off the dancefloor, allowing other nests and foraging sites to get
more support.
However, a
recent study this year found that these “beeps”
and “whoops” are much more common than we previously thought. Most bees
make these sounds when they accidentally bump into each other, meaning that the
sounds could be the bee equivalent of “oops” or “ah!” when humans are startled.
They also make these sounds when the hive is gently shaken. As a result, when a
worker bee head-butts a scout bee, the “beep” that is detected could be a sound
of alarm made by the scout bee after being head-butted instead of a signal of
disagreement made by the worker bee. Either way, it’s exciting to learn more
about the ways these tiny insects communicate!
Video 2: Bees "whoop" when they bump into each other.
Media Credits
Image 1: Flicker user westpark. https://flic.kr/p/53bLqX
Video 1: Arvin Pierce. https://youtu.be/cgSJg3oa4FE
Further Reading
Ramsey,
Michael, Martin Bencsik, and Michael I. Newton. "Long-term trends in the
honeybee ‘whooping signal’revealed by automated detection." PloS one 12.2 (2017): e0171162. doi.org/10.1371/journal.pone.0171162
Seeley,
Thomas D. Honeybee Democracy.
Princeton University Press, 2010.
Seeley,
Thomas D., et al. "Stop signals provide cross inhibition in collective
decision-making by honeybee swarms." Science 335.6064 (2012): 108-111. doi.org/10.1126/science.1210361
Seeley,
Thomas D., and Jürgen Tautz. "Worker piping in honey bee swarms and its
role in preparing for liftoff." Journal
of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral
Physiology 187.8 (2001):
667-676. doi.org/10.1007/s00359-001-0243-0
Thom,
Corinna, David C. Gilley, and Jürgen Tautz. "Worker piping in honey bees
(Apis mellifera): the behavior of piping nectar foragers." Behavioral Ecology and Sociobiology 53.4 (2003): 199-205. doi.org/
Adorable
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