Honey bee

Honey bees are mostly grouped in a genus Apis. However within the family ‘Apinae’ are stingless bees, part of the Meliponini tribe. These bees are different from honey bees producing less abundant but more liquid-based honey. This type of honey, produced by stingless honey bees, is traditionally used more for medicinal purposes.

Classification of honey bees

These honey bees are further classified as:

  • European or Western honey bee.
  • Asian honey bee.
  • Dwarf honey bee.
  • Giant honey bee.
  • Phillipinian honey bee.
  • Koshevnikov’s bee.
  • Dark dwarf honey bee.
  • Species of extinct honey bees.

European honey bee

The European bee or western honey bee (Apis Mellifera) is probably one of the most popular specie of honey bee in the world classified by Carl Nilsson Linnaeus in 1758. There are up to 20 recognized species of this bee, native to Europe, Africa, and Asia. They have recently spread to several different continents, except Antarctica. There is in fact a great economic interest behind the species as its pollination contributes significantly to the global production of food. This is in addition to their honey, pollen, wax, royal jelly, and propolis production. However, the use of certain pesticides, such as calcium polysulfide or Rottenat CER, negatively affects the species. This is why it is so important to opt for organic farming and the use of non-harmful pesticides.

Asian honey bee

The Asian honey bee also is known as the Eastern honey bee, is part of the genus Apis cerana. The Asian honey bee is similar to the European honey bee but smaller in size. It is native to South East Asia and lives in several different countries including China, India, Japan, Nepal, Bangladesh, Pakistan, and Indonesia. It has also recently been introduced in Papua New Guinea, Australia, and the Solomon Islands. A recent study confirms that the presence of this species has unfortunately decreased mainly in Afghanistan, Bhutan, China, India, Japan, and South Korea. In addition, there has also been a decrease in production. This decline is mainly due to the conversion of forests into rubber and palm oil plantations. Likewise, this specie has also been effective by the introduction of Apis Mellifera. This introduction led by South East Asian beekeepers took place due to the higher bee productivity. However, it has brought forth the appearance of various diseases in the Asian bee.

Dwarf honey bee

The dwarf honey bee (Apis Florea) has traditionally been confused with Apis Andreniformis, also of Asian origin. This is mainly due to their morphological similarities. However, these two species are commonly differentiated by one of their forelimbs which is noticeable longer in the case of Apis Florea. These species extend around 7,000 Km from the extreme East to Vietnam to southeast China. However, from 1985, its presence sprouted in Africa like due to global transport. Later some colonies were also observed in the Middle East.

Giant honey bee

The giant honey bee Apis Dorsata stands out mainly due to its large size, specifically when compared to other types of honey bees. The giant honey bee ranges between 17mm and 20mm. it lives in tropical and subtropical regions, mainly in South East Asia, Indonesia, and Australia. The giant honey bee is known for its formation of extravagant nests in trees, which are always located near food sources. Intraspecific aggressive behavior has been observed in the species during the nest migration. This occurs specifically among scouting individuals who inspect the same areas for nesting. In these cases, violent fights which include bites and stinging take place sometime results in the death of the individuals involved. It is important to note that the Laborious Apis is considered as subspecies of the Apis Dorsata.

Philippinian honey bee

Apis Nigrocincta is a honey bee from the Philippines. This bee can be found in the Philippines and Indonesia and measures around 5.5 mm and 5.9 mm. it is a specie that nests in cavities, such as holes in trunks, caves, or human structures, usually near the ground. This species, that has only been recognized relatively recently and is generally confused with nearby Apis. Due to its recent discovery, there is still not much-collected data about this species. What we do know is that it is a specie that starts new hives throughout the year. Although there are certain predisposing factors such as depredation by other species, lack of resources, or extreme temperature.

Koshevnikov’s bee

The Koshevnikov Bee (Apis Koshevnikovi) is an endemic species of Borneo, Malaysia, and Indonesia and shares habitat with Apis Cerana Nuluensis. Like other Asian bees, the Koshevnikov bee usually nests in cavities, although its presence in the environment is being severely affected by deforestation caused by tea, palm oil, rubber, and coconut plantation. Unlike other types of honey bees, this species tends to create very small colonies allowing it to survive in the rainy and humid climates. Despite this, it stores resources easily and reproduces at an accelerated rate during flowering.

Dark dwarf honey bee

The dark dwarf honey bee (Apis Andreniformis) inhabits South East Asia including China, Burma, India, Laos, Vietnam, Thailand, Philippines, Indonesia and Malaysia. It is one of the species of honey bees that has gone unnoticed for years because it was believed to be a subspecies of Apis Florea, something that various study has denied. They are darker species of their kind and create their colonies in small trees or shrubs. They do this in order to take advantage of the vegetation, going unnoticed. They usually build then near the ground at an average altitude of 2.5 m.

Species of extinct honey bees

Apart from the species of honey bees that we have already mentioned, there are others that no longer inhabit planet Earth. Shortlist of bee species that have got extinct:

  • Apis Ambrusteri.
  • Apis Lithohermaea.
  • Apis Nearctica.

Bee anatomy

Honey bees are insects and have five characteristics that are common to most insects.

  • They have a hard outer shell called an exoskeleton.
  • They have three main body parts: head, thorax, abdomen.
  • They have a pair of antennae that are attached to their head.
  • They have three pairs of legs used for walking.
  • They have two pairs of wings.

Honey Bee Head

This topic gives an overview of the external and internal structures of the honeybee’s head, the most obvious structures of the compound eyes, and the antennae. Other externally visible parts include the mandibles and the parts of the proboscis the simple eyes or ocelli and the attachments to the thorax around what is known as the occiput.

The main parts within the head are the swallowing mechanism of the pharynx the brain, three pairs of salivary glands, air sacs, the aorta, and the neurohumoral system which produces juvenile hormone and egg die soon. These various components are all contained within a solid cuticle capsule, not unlike the skull of a vertebrate.

We can see the cavities for the compound eyes and for the simple eyes or ocelli. The attachments of the antennae are close to the center of the front of the head if we look closely and the opening for the antennae, we see the small projection of the antennae fir on which the antenna is balanced and moved by the four muscles each at right angles to each other. Below the antenna openings is a raised area known as the clypeus. This covers the pharynx of the swallowing mechanism. This bulging shape provides space for the muscles which dilate the pharynx in order to create suction to either side of the clypeus are the cheeks or Gena. These contain the mandibular glands. The area above the antennae between the compound eyes is known as the front.

If we look at the back of the head we see the opening where the thorax is attached the head is balanced on two projections from the thorax from the two Episternal plates. A number of muscles attached around this opening and enabled the bee to turn the head to either side, up and down through this opening pass the main circulatory channel the aorta which terminates at the back of the brain, large tracheal trunks, bringing air to the head organs. The esophagus passing down towards the intestinal system.

The ducts of the saliva glands from the thorax and the ventral nerve cord part of the chain of central nervous system ganglia which run along the ventral side of the bee’s body. Lowermost at the back of the head is the fossa this cavity is where the proboscis folds up. When not in use within the head the main structures are the brain the swallowing mechanism of the pharynx. The three pairs of saliva glands, the largest being the brood food gland or hypopharyngeal gland in front of the brain.

The post cerebral ivory gland behind the brain and the mandibular glands within the cheeks. A large part of the lower part of the head is made up of the muscles which control the mouthparts and those which move the antennae. The structures within the head are also supplied with branches of the trachea bringing air to the tissues and there are air sacs around the brain the aorta terminates just behind the brain allowing hemolymph to circulate freely within the head and then back through the connection to the thorax and backward towards the abdomen. Behind the head are two specialized glands that produce hormones important in the development of the bee’s juvenile hormone and die so. The main internal structural components of the head are the anterior tentorial arms. These two bridges of cuticle run upwards and backward from a position below the internal openings at the front to just below the occipital foramen at the back. These structures provide attachment for many of the muscles controlling the antenna and the mouthparts and also helped to maintain the structure of the head.

The Antennae

The antenna is the universal sensory organ of the insect world and the bee is no exception its antennae are in constant use exploring the environment using touch smell taste and also testing for humidity temperature and carbon dioxide content. This information is continually being relayed to the brain and influencing and directing the bee in his actions. The main parts of each antenna are the long flagellum. This has a number of separate segments each surrounded in the cuticle. Each is essentially a rigid structure but joint into the next annulus.

There are a total of eleven of these in a worker of twelve in the year and twelve in the drone. These do not have muscles between them and move passively from and move passively with respect to each other. The flagellum is then jointed to a straight structure known as the scape via an intermediate segment known as the pedestal. The pedestal receives tendons from muscles within the scape and can be moved as will be explained later. Scape is a straight rigid structure that lifts the antenna away from the bees face and the base of the scape is articulated onto the face through a ball-and-socket joint which is moved by a set of muscles within the antennae. 

There’s a nerve, there are branches of the turkey and there’s also circulation but the most striking thing about the antennae is they’re completely covered with sensory receptors which we’ll be describing later. The drone has a much larger antenna than the worker in the Queen and the key role of the tenor for the drone is in detecting the Queen in flight. In the mating flight, the drone may have to find a queen at some distance some height up in the air and so has excellent vision and large antenna to do this and hit the antenna are particularly suited for the smell.

The total number of placards and cilia’s is about 15,000 in a drone compared to just under 3000 in the Queen’s antennae are very similar to the workers turning to the internal components of the antenna. Oxygen needs to be brought to the cells within the antenna which are metabolically very active and in common law insects option is brought directly through narrow channels through key rather than within the circulation and branches of the turkey run right through the length of the antenna. There’s also a circulation of hemolymph to bring chemicals and nutrients and so on and there’s a large nerve running the length of each antenna the nerve carries for example 48 thousand neurons taking sensation from the flat placards and silly– to the brain so there are many nerve branches within the main antenna nerve. There are muscles within scape2 muscles which are used to move the pedestal and so move the flagellum up and down in the ball and socket joint where the antenna meets the face. There are four muscles that controlled scape and balances on a small projection just inside the opening in the head and known as the antenna fir.

Turning to the sensory receptors over the surface of the antenna the most obvious ones are the round plate-like sensilli known as placoide sensilli as mentioned earlier there are about 15,000 of these in a drone and just under 3000 in a worker each of these round plates has two to three thousand pours in it through which particles are picked up from the air and stimulate the sense of smell. Some placards sincerely have a very narrow spectrum for example the alarm hormone isopentyl acetate stimulates some particular sensilli but many have a broader range of responding to many smells. There are also peg type trainer peg types in silly which may be important in taste that is very similar to the smell but a contact chemical sense. There are also depression types in silli: silaconic and silo capitola which may be involved in temperature humidity and carbon dioxide sensations. There are about five types of these and some of these are likely to be involved in smell and others in the sense of touch as touch is very important in the antenna functions.

The final organ to mention is the organ of Johnson. This cylindrical organ sits within the pedicel and is attached to a membrane in a junction between the pedestal of the flagellum. It has two main functions: one is hearing and the other is in detecting the speed of the flight as the sound creates vibrations within the flagellum which are picked up by this membrane reducing the sense of hearing but also during flight causes vibrations within them. The flagellum which is also detected here helps the bee to be aware of its speed through the air further details about the antenna and the structure of the bee can be found in the book understanding bee anatomy.

Honey Bee’s Eyes and Vision

These have two large compound eyes and three small simple eyes called ‘ocelli’. This topic however is just about the compound eyes. Like most insects, these eyes are made up of many individual units each of which produces a dot of brightness and color in the bee’s vision so that the combined eyes produce a mosaic of dots rather like the pixels of a digital camera. The worker bees each have about five thousand of these units whereas the eyes of the drones have about 10,000. If we look at each of these units consists of a hexagonal lens some of which have hair between the lens and its neighbor.

The continuous sheet of lenses is known as the cornea. Within the hexagon, each lens is transparent with an opaque area between each lens. Each of these thousands of lenses focuses light from a small arc down to the cells beneath. The diagram shows the arrangement of the cells beneath the lens. Each of these groups of cells is known as an ‘ommatidium’ and is responsible for one specific spot of light and color. If we follow a beam of light as it passes through the lens it next encounters the crystalline cone. This is a transparent structure made up of four cells which directs the light down to a long thin structure where the actual light-sensitive cells are found. The light passes down the narrow center known as the ‘Rhabdom’ between long thin cells known as ‘Retinula’ cells.

Eight retinula cells surround the Rhabdom with a ninth cell also present at the lower end of the ommatidia. The structure of the Rhabdom is quite complex. Each of the eight retinula cells has microscopic projections which pass into the Rhabdom so that Rhabdom consists of a mesh of these projections overlapping each other. These projections contain a light-sensitive chemical so that light hitting this chemical initiates an electrical pulse from the retina cell affected. This impulse is then transmitted by that particular retinular cell by a fine nerve which passes through the base of the eye.

The basement membrane and into the optic lobe of the brain first into the medulla and then with connections beyond that to the lobular and beyond it is important that the retinular cells in each ommatidia are only activated by the light coming in through the lens for that particular ommatidia and are not affected by light entering into neighboring ommatidia. To make sure that light does not spread from one unit to another each ommatidium is surrounded by fine pigment granules in pigment cells.

These can find the light to that specific or material. It is these pigment cells that give the eyes of the bee their distinctive color each individual ommatidium is sensitive to the full range of colors within the bees spectrum. We know that the bee’s spectrum is focused on shorter wavelengths than the human eye so that the bee can see ultraviolet light which we cannot but cannot really see red that we can. The color vision of bees is produced by a combination of three specific color signals in much the same way as the image on a television screen or in a digital photograph is made entirely from a mixture of three particular colors. Of the nine cells in each ommatidium, three are sensitive to light in the ultraviolet range, two to light in the blue range, and four to light in the green range. The combination of different signals from retinular cells allows the bee to sense the color of the light entering that ommatidium.

In total, the worker has about 10,000 ommatidia between the two eyes. If we think of that in the same way as a digital camera then that would be the equivalent of a 10 killer pixel camera which would really produce a very coarse image. In the same way, the bee’s vision is much coarser than a human eye the human can see a hundred times the detail than a bee’s eye can. However, where the bees eye is superior to the human eye is in its ability to see movement, the human eye cannot really see an image which changes see new images faster than 30 times a second this is why the film is seen as a moving image rather than as a series of photographs and why fluorescent light appears continuous rather than a series of flashes 50 times per second. The bee’s eye however can see a hundred and fifty images or more per second in each or material and this allows it to be very sensitive to movement. Despite its poor resolution, the bee’s eye is entirely adequate for navigation over several miles avoiding obstacles, finding flowers, and finding its way back to the right hive.

Brain of Honey Bee

The brain of the honeybee is quite remarkable in its capability despite its small size of about one cubic millimeter. The bee is able to find its way home across five miles or so of terrain. Bee builds perfect hexagonal combs and arranges these carefully next to each other. Bee is able to communicate to other bees in the hive describing the location of forage of nectar sources etc. It can remember the details of its locality.

Within the insect world, the bee does have a larger brain than most others. It has ten times the number of neurons of a fruit fly and about four times the number of an end. Turning to the development of the bee’s brain, the first evidence of the brain can be found within the egg. The egg takes three days before hatching and within the egg, some form of the segments of the bead takes place and the brain can be seen to be developing in the egg stage. It continues to grow through the larval stage and it’s one of the few structures within the larvae which is not reabsorbed during metamorphosis.

In the pupil stage, most other structures are dissolved and reconstructed but not the brain that continues right through turning to the structure of the brain. In the adult bee, the brain stretches across the upper part of the head between the compound eyes. It’s relatively narrow from front to back if we look at the different regions of the brain starting from the outer aspects, we have the compound eyes then the medulla, the lobular, the antennae lobe at the front then in the center, the alpha and beta lobes and the medial and lateral calyx. Each one called a calyx and then beneath all of this, there’s the subesophageal ganglion and in the center of the brain, there’s a hole. This is a common feature to insects that the feeding tube, the pharynx, and the esophagus actually passed through the center of the brain with the subesophageal ganglion beneath it. It gets its name because it is below the esophagus and this is common to insects quite a bit is known about the function of different parts of the brain and I’ll just touch on a couple of these areas.

We know that the functions of social behavior and memory are located within what is known as the mushroom bodies. They call that because in some insects they appear like a nucleus at the end of a stalk hence the term mushroom bodies. It’s not so obvious in the bee but these consist of the medial calyx, lateral calyx, and the alpha and beta lobes, and these areas that mushroom bodies are particularly highly developed in bees. These lobes the front of the brain of the internal lobes and this is where all the signals from the antenna. The antenna eye has a huge number of sensory receptors and these are processed within the antennae lobe. This is where all of the processing of smell signals takes place and within the internal lobe clumps of cells known as neuropil clamps.

There are a number of these throughout the internal lobes that are quite similar from one bee to the other and these are known as ‘glomeruli’. The lower part of the brain is the subesophageal ganglion and this controls incoming and outgoing signals to the mouthparts and the proboscis. On each side, there are three nerves which go to the mandibular, maxillary and labial structures. Within the mouthparts at the back of the subesophageal ganglion, there are paired nerves which form the first part of the ventral nerve cord which leaves the brain here passes through the neck and then runs along the lower part of the body through the thorax and abdomen to seven ganglia along the length of the body which have the connections for the different body segments four legs, four wings and so on.

Structure of Honey Bee’s Leg

The bee’s legs are equipped with a wide range of tools. This overview looks at the basic structure of the legs, the segments, the muscles, and some of the specific tools. All three casts Queen drone and the worker have the same structure for their legs and all three legs, front, middle, and back have the same segments although their details differ a typical insect leg has six basic segments.

However, in the bee, one of these the Tarsus is further divided into four parts meaning that the honeybee leg has nine segments all together. From the body to the ground these segments are the coxa, trochanter, femur, tibia, basitarsus, three tarsomeres and the pretarsus or foot.

In the first of these segments, the coxa is a small segment that is hinged directly to the thorax. It pivots by two articulations and the axes between these two points are transverse so that the coxa basically swings forwards and backward in anatomical terms. These are referred to as promotion and remotion. The axis of the middle leg is angled slightly backward and of the rear leg even more back so that when the coxa swings forward it also swings outward so the movement of the coxa is responsible for the forward and backward movement of each of the legs.

The next segment is the trochanter. This is also a fairly short segment. The axis of this joint is horizontal so that the trochanter swings up and down with respect to the coxa it is this joint which is responsible for upward and downward movement of the leg as a whole.

The trochanter is then jointed to the femur is generally the larger segment in an insect leg. The joint between the trochanter and the femur is long and diagonal with articulations at the top on the bottom these articulations allow a small amount of forwarding and backward movement at this joint but though upward or downward movement so that effectively the trochanter and the femur largely move as one unit.

The next segment is the tibia which is jointed to the femur at a large joint which could be considered as the bee’s knee. At this point, the tibia points downwards with respect to its joint with the femur. The tibia of the rear leg is quite different in shape to that of the other two legs. The tibia is also the last segment to contain muscles. All segments from this point onwards are controlled by a single tendon. This is operated by two muscles, one in the femur and one in the tibia which both pull on the same tendon responsible for all movements after the Basitarsus.

The basitarsus is the next segment after the tibia it only has a single point of articulation with the tibia. The next the final segment is the pretarsus or foot this contains the gland which produces a footprint order known as the lionheart gland and also has two claws. If we look at the foot itself at the top of the pretarsus towards the front of the cuticle, our two knobs onto which are articulated the two claws. Between these is the is a plate of cuticle known as a manubrium which attaches at its lower end. This is the adhesive pad. It has sufficient adhesive force on smooth surfaces for a bee to hang upside down by its feet and to bear the weight of other bees hanging from it although the Queen and the drone do not need the specialized functions for pollen gathering. Nevertheless, the shapes of their legs are very similar to those of the worker that concludes this overview of the anatomy of the honey bee’s legs.

Social Life of Honey Bees

How Honey Bees Get Their Job? The honeybee is one of the most collaborative insects in the world. Each hive is comprised of thousands of bees working together in order to build and sustain a colony. Within the colony, each bee has a specific role to play a job. These are jobs like foraging for food tending to young larvae and building a honeycomb but with a brain about the size of a sesame seed. It begs the question how do bees know what specific job they need to do in order to keep a balance in the hive the answer is written into the genetic makeup of each bee and it starts with the queen bee who has the unique ability to designate the sex of her children which plays a pivotal role in their future. If the queen wants to lay a female egg, she will fertilize the egg by releasing spermatozoa that are stored in the spermatheca which sits behind her ovaries. The spermatheca is filled during her first week of life when she mates with up to 20 drones or male bees. If the Queen wants to lay a male egg she will not release any spermatozoa as the egg leaves the ovaries and drones have a singular job that job is to mate with queens from other colonies to propagate the species. When they’re not trying to mate, they eat leisurely from the honey reserves and wait for a queen to go on her. Nuptial flight female bees or worker bees do literally everything else. They keep the cells clean care for the larvae build cells tend to the Queen, store honey, forage, pollinate, guard the nest and even feed male bees honey if they’re begging for it each bee knows what to do because their hormones activate the part of their genetic makeup that tells them what jobs they have to tackle and when they have to tackle it. They go through four phases of jobs before dying.

In phase one, bees go to work immediately after they emerge from metamorphosis. About three weeks after they’re born they begin cleaning the cells from which they emerge, after about three days their hormones shift them into nurse bee mode. In this job, they feed the young brood that succeeds them. This lasts for about a week then phase three kicks in and the workers become general handyman moving farther away from the center of the hive and doing things like building honeycomb, storing food, and guarding the nest entrances. This lasts about a week. The final phase is the most dangerous. It’s the foraging feast where workers leave the nest to find pollen to bring home and feed the colony this phase starts around day 41 and lasts until about day 50. After a short life of constant work, most workers will leave the nest as death approaches the corpses of those that die inside the hive are carried out by undertaker bees. It’s a thankless life for the worker bee but this collaboration and process has made them one of the most successful super organisms in nature.

References

  1. Franck P., Garnery L., Solignac M. & Cornuet J.M. (2000). Molecular confirmation of a fourth lineage in honeybees from the Near East.
  2. Apidologie Abu-Asab M., P. Peterson, S. Shetler, S. Orli. (2001). Earlier plant flowering in spring as a response to global warming in the Washington, DC, area.
  3. Biodiversity and Conservation AFSSA. (2009). Weakening, Collapse and Mortality of Bee Colonies.
  4. French Food Safety Agency. Baker, R. J. (1971). The influence of food inside the hive on pollen collection by a honeybee colony.
  5. Journal of Apicultural Research. Bankova, De Castro, S. L. and Marcucci, M. C. (2000).
  6. Propolis: recent advances in chemistry and plant origin. Apidologie.
  7. Fewell, J. H. and Jr. Page, R. E. (1993). Genotypic variation in foraging responses to environmental stimuli by honey bees, Apis mellifera. Experientia.
  8. Gary, N. E. (1975). Activities and behavior of honeybee. The Hive and the Honeybee. Hamilton, Illinois: Dadant & Sons.
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