Every living creature has a way of breathing. Some breath through the lungs, gills, or skin [1]. However, most animals, like mammals, birds, and reptiles, breathe through their lungs, including humans, which are commonly located in the chest. For humans, we breathe air through our mouth and nostrils and moves through the trachea and into our lungs [2].
This begs the question of how insects, like bees, breathe. Do they breathe through the lungs, gills, skin, or something different?
Bees, like many types of insects, don’t have lungs that are similar to what people have. Instead, they have ten pairs of portholes from their thorax and abdomen called spiracles that they use to absorb oxygen and also to push out carbon dioxide [3]. These spiracles are also connected to a tube-like structure called the trachea and to trachea sacs used for oxygen to flow inside the bee’s body [4].
Let us learn more about how bees breathe, even if they don’t have lungs.
Do insects, like bees, breathe oxygen?
Like most living organisms, insects like bees also breathe in oxygen by inhalation and expel carbon dioxide by exhalation. This process is called respiration, which is similar to how humans exchange gas.
However, they don’t breathe in the same fashion we’re accustomed to because they don’t have the same respiratory system as humans. Since we’re talking about bees and not humans, we can find similarities in function but from different organs.
Do bees have lungs?
The animal kingdom is filled with many interesting ways of breathing from different types of animals.
However, we are more accustomed to the usual way of breathing by mammals, including humans, where our respiratory system starts with our mouths and nostrils, through the trachea (windpipe), and into our lungs.
Then, there are the fishes that breathe through their gills. Finally, the amphibians, like frogs and toads, have a specialized type of skin that they use to breathe.
However, it is a different story when it comes to most insects. Bees, like many types of insects, don’t have lungs. Instead, they have portholes along their bodies (from the thorax to the abdomen), called spiracles, which they use to allow oxygen to directly move through their bodies.
They also use these spiracles to expel carbon dioxide from their bodies, thus, completing the oxygen exchange.
How do bees breathe?
The respiration of bees involves several parts, which are distinct compared to what humans have. The most essential aspects of the bee’s respiratory system, which are also similar to other insects, are the spiracles, trachea, and trachea sacs.
1. Spiracles
Bees, like many types of insects, have ten pairs of spiracles located throughout their body – from the thorax or their upper body, all the way to their abdomen.
The spiracles are used by insects to allow air to enter their body through their trachea and into their air sacs. They serve the similar purpose of how we use our mouth and nostrils to inhale and exhale.
For bees, they have three pairs of spiracles on their thorax (upper body), while the remaining seven pairs are located in their abdomen (lower body). They even have one pair of spiracles situated in the sting chamber of the abdomen.
During the development cycle of a bee, its spiracles can already be visible as early as during their larval stage, which can be identified as the black dots along the body of the larva. Eventually, the network of the trachea will also start to appear.
2. Trachea
For humans, the connection of the mouth, nostrils, and throat going to the lungs is through the trachea or the windpipe [6]. However, though insects also have similar tubes called tracheas, they have different functions and connect different parts.
The spiracles of the bees are connected to a tube-like mechanism called the trachea, which will eventually divide into smaller tubes called tracheoles that acts as the insect capillaries [5] that are vital in the gas exchange.
The oxygen in these tiny tracheoles will then diffuse to the bee’s tissues, which they will use in their day-to-day tasks. The tracheoles can be likened to the bronchioles of human lungs.
Afterward, the carbon dioxide that has built up on the tissue of the bee will be expelled and squeezed from its tissues to the trachea sacs and then outward through the same spiracles.
3. Trachea Sacs
If humans have lungs, bees have tracheal sacs or air sacs that are located along the tracheae on different parts of the bee, from the head, thorax, abdomen, and even in their legs. These air sacs can be expanded and contracted wherever the bee needs oxygen.
The bee’s abdomen controls the flow of air into and out of the sacs and identifies which part needs air. These sacs can also supply oxygen from the top to the bottom of their body and also along the stretch of the abdomen.
Do bees also experience and die from suffocation?
It may sound odd, but bees can also die from suffocation when the airways are blocked and no oxygen enters the body.
Since they still breathe oxygen, limiting the supply of it is critical and can kill them. Suffocation of bees is most notable from queen bees that die from bee balling or thermo-balling. However, it is also one of the ways that bees defend their hive against other invading insects.
Balling is one way the worker bees do if they want to kill their old queen bee during the process of supersedure. This usually happens just before a new queen bee emerges to take over the hive.
What happens is that several worker bees will gather around their target, and they will squeeze its abdomen and thorax tightly to block the spiracle. This is like covering the mouth and nose of the victim. However, insects have ten pairs of spiracles, so more bees are needed to cover every hole.
Smothering a bee covers the spiracles they use to allow air to enter the body that supplies their oxygen.
By balling the victim, aside from covering up their spiracles, they also increase the victim’s body temperature, overheating and suffocating to death.
So, once these spiracles are covered up, a bee, or more commonly, the older queen bee, will suffer from suffocation and die. It is similar to plugging a person’s mouth and nose so they can’t inhale.
Suffocation is also another way for bees to kill some of their predators, like the hornets. Based on research, the average time of smothering before a hornet dies of suffocation is 57.8 minutes [7].
Are bees also susceptible to respiratory diseases or parasites?
Bees, like many animals, are also susceptible to respiratory problems like parasites. However, their parasites are not the same as what humans have.
One of the common respiratory infestations for honeybees is tracheal mites. These microscopic mites can be as long as 1.5x the human hair’s diameter [9].
Tracheal Mites (Acarapis woodi)
Tracheal mites have the preference for infesting the tracheal system of adult honeybees. They enter through the spiracles located at the bee’s thorax to the trachea, where it will attach to the wall to start feeding off it.
Once the mites are inside the bees’ tracheal system, they will puncture the tracheal wall and draw out the hemolymph of the bee, which is equivalent to the blood of invertebrates like insects.
Once they enter the tracheal system of the bee, these tracheal mites will breed and lay eggs in it, eventually blocking the trachea tube and disabling the bee’s capability for oxygen exchange, which is lethal to the unsuspecting bee and can cause complications and death.
Tracheal mites are most prevalent during the winter and spring and can decrease bees’ honey production by up to 30%. These mites are also highly transmissible and can be transferred from bee to bee, which can cause a colony’s winter survival rate to plummet [8].
If not properly treated early on, the infestation of tracheal mites can destroy bee colonies.
How to control Tracheal Mites
Tracheal mites can be controlled using menthol, which is commonly available to supply stores. The menthol can be activated if the temperature is above 60 degrees Fahrenheit. It helps the bees by breathing in the vapor that can cause the parasites to wither.
Conclusion
Bees, like every other animal, have to breathe. However, the difference between most animals and insects is how they breathe. We may be more familiar with breathing through the lungs for humans, the gills for fish, or the skin for many amphibians.
However, bees and other insects breathe not through their lungs, gills, or skin but through their spiracles. These portholes along their bodies become the air passage for inhaling oxygen and exhaling carbon dioxide.
These spiracles are then connected through the tube-like trachea to the air sacs located throughout the bee’s body and legs.
References:
[1] – https://www.animalfunfacts.net/knowledge/senses-and-abilities/376-how-do-animals-breathe.html
[2] – https://letstalkscience.ca/educational-resources/backgrounders/respiratory-system-in-vertebrate-animals
[3] – http://www.udelas.ac.pa/site/assets/files/4247/how_insects_breathe.pdf
[4] – https://americanbeejournal.com/respiration-and-circulation-in-honey-bees
[5] – https://my.clevelandclinic.org/health/body/21988-capillaries
[6] – https://www.lung.org/lung-health-diseases/how-lungs-work
[7] – https://www.abc.net.au/science/articles/2007/09/18/2036113.htm
[8] – https://bees.caes.uga.edu/bees-beekeeping-pollination/honey-bee-disorders/honey-bee-disorders-honey-bee-parasites.html
[9] – https://www.clemson.edu/extension/beekeepers/fact-sheets-publications/tracheal-mite-honey-bee.html
