The Science of Bees

Bees and the Environment

For such small, docile creatures, honeybees have a tremendous impact on our environment and food supply. Pollination of plants provides us with much of our fruits and vegetables as well as with beautiful plants in peaceful fields and gardens. For the meat eaters in the population, bees’ pollination efforts also provide food for the animals that wind up on omnivore’s plates.

Foraging and Pollination

Honeybee Foraging

David Lescard

Honeybees are our most critical pollinator. Nature itself designed this relationship. For millions of years, pollinators, including honeybees, and plants evolved in partnership with each other. Plants developed to attract insects with specific traits suitable for drinking their nectar and insects developed along side them the necessary traits to feed on the plant life. In the case of bees, their eyes and senses of smell, taste, and time also adapted to locate the best food supply. Those adaptations proved most beneficial for plants as well.

Today, this means that honeybees are responsible for pollinating 90 percent of the food supply and visit 50 to 100 flowers each foraging trip. They use their amazing sense of time to assess if the food supply is a reasonable distance. Bees want to ensure they don’t use more energy than they will be able to collect from the source. They’ve been known to fly up to eight miles on a foraging trip, but typically like to stay closer to home and seek foraging locations within two to three miles.

Honeybees also discriminate food sources. While humans have a variety of food each meal, bees opt to visit only one flower species per trip. This discrimination is certainly beneficial to plants as it provides a pure transfer of pollen, enabling the plants to remain one species and not become a hybrid. Honeybees will, however, visit more than one plant type on a foraging trip if they’re in a high variety area or if nectar and pollen levels drop. On a day with ideal weather and plant conditions, bees can visit up to 40 plants on one foraging trip and will make five to fifteen foraging trips per day.

Pollen is collected via static electricity when bees land on the flowers and is stored in sacs on their legs. Nectar collection requires one of bees’ special adaptations: the proboscis. The proboscis is a carefully adapted tongue that functions like a pump. Bees stick their proboscis in the flower and pull out nectar. The nectar is swallowed, but rather than entering the bee digestive tract, it is stored in a specially developed sac located at the bottom of the esophagus above the stomach. While the bee is in flight returning to the hive, she adds more saliva to the nectar. Bee saliva also contains a special adaptation: invertase. This enzyme, found no where else in nature, works to break down the complex sugars in nectar to simple sugars i.e. honey,

When the bee returns to the hive, further special care is taken to store this partially converted nectar in the waiting honeycomb, where the remaining conversion to honey takes place. The nectar is passed from bee to bee, each one adding more invertase until it’s placed in a cell of the comb. When nectar flow is very high, partially converted nectar may be stored and additional invertase added when nectar flow slows. When flow is slower, the bees fully convert the nectar to honey and store it in the comb, capped and stored to sustain them through the winter.

The Anatomy of Bees

Honey Bee Anatomy

Antennae

Since honeybees use their antennae for touch and smell, it’s critical they’re clean and in good working order at all times. Bees will use their legs to groom themselves with particular attention to their antennae.

Honeybee antennae are used to communicate with their hive family via touch and assist in finding food sources. They’re also used by worker bees to measure the size of comb cells under construction to ensure they come out perfectly each and every time.

Head

A honeybee’s head contains a super computer. Although their brain is about the size of a sesame seed, it is capable of performing complex learning and communication tasks such as directionality with more accuracy than even the most modern GPS and language in the form of the waggle dance and pheromone interpretation.

In addition to holding such an amazing brain, the honeybee head also houses the hypopharyngeal gland which secretes a protein that is used to feed larvae and is critical in the production of the royal jelly necessary to feed the queen. Queens, from larvae until death, eat only royal jelly, making the hypopharyngeal gland critical to hive survival.

Honeybees are the bloodhounds of the insect world. Each tiny honeybee head is home to 170 odor receptors, giving them a sense of smell so precise they can tell the difference in hundreds of flower types and distinguish if a plant contains pollen or nectar from miles away. For reference, fruit flies have only 62 odor receptors and mosquitoes only slightly more at 79.

Thorax

The thorax, immediately behind the head, is where the wings attach. Capable of beating up to 200x per second, the wings create the unique buzz sound associated with bees flying. Thorax muscles cause the wings, which hinge together during flight, to twist with each flap, powering the bees forward with speed and precision.

Abdomen

A honeybee’s abdomen can carry about 75mg of nectar from flower to hive each foraging trip. To produce 1kg of honey, the entire hive will orbit the earth three times. Thankfully, just one ounce of honey will sustain a bee for one full trip around the earth.

Compound Eyes

With their two compound eyes, bees are able to see in an omni-directional fashion. These eyes are located on each side of the head and provide a full surround view of their environment. Bees see colors on the UV spectrum, outside of human capabilities. Although this means they cannot see the color red, they do see the UV pattern of red flowers and forage on them as frequently as flowers of any other color. Bees also have their own version of the color purple that is outside human’s visible range.

Simple Eyes

Located on the top of the head and used to triangulate direction, the three simple eyes are particularly important for bees to navigate. Important targets (hive entrance, food sources, etc.) are recorded by the simple eyes as something akin to a GPS point. Both the two complex eyes and the three simple eyes are covered in hair. Despite how uncomfortable that sounds, the hair keeps foreign debris for getting in their eyes.

Mandibles

The mandible, or jaw, is particularly strong and sharp. Bees use these bones to defend the hive and to cut wax and other hive products. Bees first use their mandibles to cut themselves out of their capped larval cells once fully matured. The salvia contained in the mandible also as an anesthetic effect.

Proboscis

The proboscis, or tongue, is covered in hair and folds behind the bees’ head. It is used in nectar collection. The proboscis functions like a pump, pulling nectar out of even the most long, tubular flower shapes. Here is a video of a bee extending its proboscis.

Wings

Honeybees’ wings are incredibly strong, enabling them to fly up to six miles at 15mph, yet using so little energy that a single ounce of honey could power a bee’s flight around the entire world. The distinct buzzing sound associated with bees in flight is actually the rapid flapping of their wings. In winter months, bees are capable of detaching their wing muscles from their spines in order to flap them in a shivering like motion to generate heat in the hive.

To propel themselves, bees using a twisting action with each wing flap, similar to a propeller with up and down strokes. In flight, the front and rear wing pieces hitch together and work in unison twisting and flapping.

Legs

Unlike most insects, bees have feet! These feet are specially adapted to stand on a variety of surface types. The “toes” are claw-like to help them stand on rough surfaces such as a tree branch. The remaining soft padded areas provide greater surface area and friction so they can stand on smooth surfaces like flower petals.

Stinger

Honeybees use their stingers only in defense. When female bees feel their brood or food is endanger, they sting the perceived threat and die in the process. Male bees do not have stingers. When a female bee stings a threat, the barbed end of the stinger hooks in and causes the stinger to be pulled off as the honeybee tries to fly away. This kills her, but also releases the alert pheromone, warning her sisters of potential danger.

As more bees respond to the alarm and sting the threat, more pheromone is released and the hive grows more agitated. Thankfully, honeybees do not chase. When the threat moves away, they get back to work.

For the 98 percent of the population who does not have an anaphylactic allergy to bee stings, estimates indicate that a person would have to be stung 1000 times at once to die from bee stings.

Bee Senses

Smell

Honeybee odor receptors are more powerful than those of fruit flies or mosquitoes. They are so powerful in fact that scientists are developing ways to use bees to detect bombs and other threats. One current prototype puts three honeybees in a box being viewed on video by human interpreters. Bees respond with agitation to explosive scents at concentrates equal to that of a grain of sand in a large swimming pool (two parts per trillion). In addition, unlike dogs, bees do not easily get distracted from their task, need no reward to perform, learn more quickly, and are cheaper and easier to maintain. The ethical and moral implications of using either bees or dogs will not be discussed here. Check out this video of scientists at the Los Alamos National Laboratory learning to use honeybees to locate explosives.

Their super sense of smell also helps bees identify each other. Each hive has its own odor and bees whose odors do not match will not be allowed in the foreign hive. Bees will defend their hive from intruders to the death.

Touch

Bees primarily use their antennae to communicate with touch. They touch each other in the process of their waggle dances indicating food sources and sites for new hives. They also use touch to gauge the dimensions of each cell in comb while it is being built. Bees are often seen using their front legs to clean their antennae because touch is so critical to their survival.

Sight

Bees see on the UV spectrum and use it to locate food. They can perceive a “landing strip” in front of flowers. They also have a variation of purple that humans can’t see.

In a superhero-like adaptation, honeybees can also sense electric fields and distinguish their shapes and sizes. As bees fly through the air, they create a positive electric charge. Flowers typically have a negative charge. When a positively charged bee lands on a negatively charged flower, pollen transfers via static electricity.

Bees can also tell the size and shape of the electric fields around flowers and use it in conjunction with their other senses to locate appropriate food supplies. Scientists were able to test bees’ abilities at perceiving electric fields and successfully proved that bees can sense both size and shape of electric fields.

Pheromones

Bees use pheromones to communicate. Each pheromone scent means something specific to the bees. For example, the alarm pheromone smells like bananas, leading many beekeepers to forego bananas during the hive-checking season. The more concentrated the smell, the stronger the bees will react to it.

Queen Mandibular Pheromone (QMP)

Bee Swarm

Mark Osgatharp

QMP is the most influential of the pheromones. It is more present in small hives than larger ones. In smaller hives, high levels of QMP encourage the bees to build brood comb and increase their numbers. In over-crowded hives, the lower QMP levels let the bees know when to start building queen cups in preparation for swarming.

Despite what Hollywood portrays, swarming is actually a sign of a healthy, robust hive. It means that the population of the hive has outgrown the size of its home. To deal with the over-crowding, bees create another queen and effectively split their family in half. The half that leaves the hive is known as a swarm.

Consisting of only nine compounds, QMP smells like lemongrass essential oil and regulates the size and make up of the hive. A hive will always need more worker bees (female) than drones (male), but depending on the levels of QMP present, more of one or the other will be needed. Worker bees will construct comb appropriate to the size needed for the workers (smaller cells) and drones (larger cells) and in the appropriate quantities based on the messages in QMP.

The queen is the mother of all bees in the hive. When she is healthy and QMP levels remain acceptable to the bees, it inhibits worker bee fertility and prevents new queens from being produced. It also aids in family recognition. Each bee in the hive will have a scent corresponding to their mother’s QMP and foreign bees will not be accepted as family.

Breeding and Genetics

Knowing the lifecycle stages and times can help beekeepers know if the hive is in trouble. Even if you can’t spot the queen during a hive check, seeing bees at each stage of the cycle at appropriate times is a good indication that the queen is healthy.

Worker

Worker bees, the ladies, take 21 days to go from larvae to full adult. When initially laid, they’ll look like grains of rice in some gel within an uncapped comb cell. After 9 days, these cells will be capped. At this stage, it looks a lot like Kix cereal. Sunken of discolored caps can also be a sign of hive trouble. At day 21, the adult bee uses those sharp mandibles mentioned earlier to cut her way out of the capped cell.

Drone

Drone Bee Sex Organ

Michael L Smith

Drones, the males, take 24 days to become fully crown adults. Their cells are capped at 10 days and will look similar to worker bees’ cells, only slightly larger. Just as the workers, drones will use their sharp mandibles to cut their way out of the capped cell. For drones this occurs at 24 days. As with the workers, sunken or discolored caps can be a sign of trouble.

Bee Math

To assess the health of their hive, beekeepers can use this information to do some “bee math.” If hives are inspected on a weekly basis (every 7 days), the second hive check (14 days) should have both capped and uncapped larvae. The third check (21 days) should have evidence of born worker adults (open comb where there were capped cell and/or browning comb) and capped and uncapped larvae. The fourth check (28 days) should have all of that plus evidence of born drones (assuming there were any at the larval stage.

If bees are not emerging from their capped cells on schedule, this can be a sign of trouble. As can lack of new larvae in peak laying season. As colder months approach, bees will shift their focus to shrinking the size of the hive and storing food to sustain them in the harsh months.

If the hive is inspected and evidence of worker bees (capped cells after 9 days, births after 21 days) is missing, it is likely that the queen is ill or missing and a more thorough search for her should be conducted. If she cannot be found, a new queen must be introduced to the hive to avoid “laying workers.”

The queen is the only bee in the hive to be fertilized by a male bee. If she is gone and the bees do not immediately replace her, the remaining worker bees will attempt to lay eggs and grow the hive, but because they have not received the male portion of genetic material, they are only capable of laying drones. Drones will not fertilize a worker bee and do not forage. If this laying worker situation continues too long, the hive will fail as the number of worker bees dwindles and the drone bees become the sole inhabitants.

Queen

Queen Cell For Swarm

Maja Dumat

The queen is the mother of all bees in the hive. She regulates the hive and participates in creation of a new queen when the hive becomes too crowded so that half of the hive can leave in a swarm. Other bees can also make a queen from worker bee cells if the hive becomes aware of her absence in time to correct it.

The queen’s cell looks completely different from that of workers or drones. Rather than being embedded in the comb, a cell called a queen cup is built. In the case of swarm preparation, the queen cup is pulled from the edge of the comb into a long, skinny cup and the existing queen turns herself upside down to lay the egg inside it.

In the case of the hive replacing the queen, an existing worker cell is pulled and twisted off the front of the comb into the queen cup and the bee becomes a queen instead of a worker. In both instances, the larva is fed only royal jelly and the queen emerges between 14 and 16 days after being laid. Capping of queen cells occurs at 7 to 8 days. This video captures the life cycle of the queen and her one emergence from the hive to mate with any available drones in the area.

The more drones the queen is able to mate with, the greater the genetic diversity of her hive will be and therefore hardier and more likely to succeed.

Combating Colony Collapse Disorder

Colony Collapse Disorder (CCD) is the biggest threat to hives today. There are numerous theories about the root cause including neonicotinoids, which are a class of pesticides used in nearly all large agricultural business, including plants purchased by consumers and places like Lowes, Home Depot, and other garden centers. The use of neonicotinoids is slowly waning, but it may not be fast enough to stop CCD. And still, no one is completely certain it’s the whole cause.

CCD is heartbreaking for beekeepers. At one hive check, all seems fine; at the next, the bees are gone. So gone it’s like they were never there. There’s no sign of where they went; they’re just gone, never to be seen again. Thankfully, there are many efforts underway to help the bees survive and, hopefully, stop CCD.

The honeybee genome is not as diverse as other wild animals, due to human interference over the years trying to breed bees that are docile and disease resistant. Scientists at Washington State are trying to reverse this damage and increase the genetic diversity of bees in the U.S. They believe that greater diversity will lead to greater tolerance for environmental imbalances and changes caused by human and non-human factors.

To do this, they’ve started a bee sperm bank. By working with the sperm of bees from Italy, Georgia, and other countries on the Eastern Alps, this group of scientists is conducting experiments in selective breeding to hopefully breed hardier bees and then introduce those bees to the American population. The sperm from these drone bees is frozen and manually placed inside a queen bee. Since the queen determines the genetic makeup of the hive, all the bees she lays will have this more diverse genetic makeup.

Coupled with the sperm bank is artificial insemination. A key figure in this area is Susan Cobey, also in Washington State. On her organic farm on an island in Puget Sound, Cobey raises drone bees specifically to survive harsh winters. She then extracts their semen and fertilizes queen bees in the hope that a winning combination will emerge: a bee sharing all the resilient aspects from both parents, but yet are still docile and gentle enough for the backyard beekeeper. Cobey believes she may not achieve this in her lifetime, but feels she must try. The bees need her to keep at it.

Hive threats will be thoroughly covered in a future article, but they are also a potential factor in CCD. Some bees, however, have a genetic resistance to at least one of the mite pests. Researches with the Agricultural Research Service are working to breed bees that have this built in resistance. Bees who possess this gene actually seek out the mite as it attacks the larvae and destroy it. Combining this with bees who possess diverse genetic material making them hardier might also be a possibility.

Another attempt at altering the honeybee genome to a hardier state is hybridization. Bees from Australia and an Africanized strain in Sao Paolo, Brazil show a particular resistance to CCD. Bees are actually native to Africa and were brought to Europe and then America by humans. Unfortunately, the Africanized strain has already migrated up into parts of the southern U.S. and has killed at least 13 people. Their incredibly aggressive nature makes them a poor candidate for breeding with the honeybee. The bees from Australia, however, appear to be docile enough and appear to have the same resistance to CCD.

Summary

Bees are among the most studied, yet least understood animals to share our world. They are critical to our survival, yet constantly at risk of extinction. Being so little understood, humans are still discovering ways to help them, and in doing so will hopefully save all of us.

Bees begin life no larger than a grain of rice and become full adults in less than a month’s time. Drone bees do not do any of the foraging or hive work, but are critical to bee genetic diversity and hardiness. The worker bees move up the ranks from inside workers to foragers. The foragers put food on our plate and honey (aka bee food) in the hive. Still quite tiny, yet amazingly smart and strong, foragers will travel miles for acceptable pollen and nectar sources and require very little nourishment to do so.

In their lifetime, an entire hive will fly a distance equal to three times around the earth seeking food, pollenating flowers, and providing humans with food. Most of the honey they make on their foraging trips will be preserved for winter sustenance, as they require only one ounce of the sweet stuff to fly the distance of one trip around the earth.

Their incredible foraging productions are the result of nature’s engineering. Bees and plants evolved alongside each other. Plants to attract and be accessible to bees and the bees to locate and use flower resources. Bees aid flowers in passing their own genetic material, which frequently results in human food. Ninety percent of the food we eat is thanks to the industrious honeybees.

Colony Collapse Disorder and other threats are causing the bee population to dwindle. Scientists are constantly seeking the cause and possible solutions. Many believe the cause to be chemicals used in agriculture, specifically neonicotinoids. Possible solutions typically involve breeding bees. Some options for this include bee sperm banks, hybridization, and raising drones for specific traits to breed with queens.

These fascinating and mysterious creatures incredibly advanced, especially for their size. This article merely scratches the surface of their wonders, but hopefully compels you to want to know more.

AUTHOR: Sarah Woodard

References

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