European honey bee
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The European honey bee or western honey bee (Apis mellifera) is a species of honey bee. The genus Apis is Latin for "bee", and mellifera comes from Greek melli- "honey" and ferre "to bear" — hence the scientific name means "honey-bearing bee". The name was coined in 1758 by Carolus Linnaeus who, realizing that the bees do not bear honey, but nectar, tried later to correct it to Apis mellifica ("honey-making bee") in a subsequent publication. However, according to the rules of synonymy in zoological nomenclature, the older name has precedence. As of October 28, 2006, the Honey Bee Genome Sequencing Consortium fully sequenced and analyzed the genome of Apis mellifera.
In 2007 media attention focused on Colony Collapse Disorder, a decline in European honey bee colonies in a minority of regions of North America.
Subspecies originating in Europe
- Apis mellifera ligustica , classified by Spinola, 1806 - the Italian bee. The most commonly kept race in North America, South America and southern Europe. They are kept commercially all over the world. They are very gentle, not very likely to swarm, and produce a large surplus of honey. They have few undesirable characteristics. Colonies tend to maintain larger populations through winter, so they require more winter stores (or feeding) than other temperate zone subspecies. The Italian bee is light colored and mostly leather colored, but some strains are golden.
- Apis mellifera carnica, classified by Pollmann, 1879 - Carniola region of Slovenia, the Eastern Alps, and northern Balkans - better known as the Carniolan honey bee - popular with beekeepers due to its extreme gentleness. The Carniolan tends to be quite dark in color, and the colonies are known to shrink to small populations over winter, and build very quickly in spring. It is a mountain bee in its native range, and is a good bee for colder climates.
- Apis mellifera caucasica, classified by Pollmann, 1889 - Caucasus Mountains - This sub-species is regarded as being very gentle and fairly industrious. Some strains are excessive propolizers. It is a large honeybee of medium, sometimes grayish color.
- Apis mellifera mellifera, classified by Linnaeus, 1758 - the dark bee of northern Europe also called the German honey bee - domesticated in modern times, and taken to North America in colonial times. These small, dark-colored bees are sometimes called the German black bee.
The hybrid populations of A. m. mellifera x A. m. ligustica , found in North America and Western Europe, have the reputation of stinging people (and other creatures) for no good reason. The near-extinct "pure" A. m. mellifera is not considered randomly aggressive.
- Apis mellifera iberiensis (aka Apis mellifera iberica), classified by Engel, 1999 - the bee from the Iberian peninsula (Spain and Portugal)
- Apis mellifera cypria, classified by Pollmann, 1879 - The island of Cyprus - This sub-species has the reputation of being very fierce compared to the neighboring Italian sub-species, from which it is isolated by the Mediterranean Sea
- Apis mellifera ruttneri, classified by Sheppard, Arias, Grech & Meixner in 1997- is a sub-species originating in the Maltese islands.
- Apis mellifera sicula, classified by Montagano, 1911 - from the Trapani province and the island of Ustica of western Sicily (Italia)
Subspecies originating in Africa
Several researchers and beekeepers describe a general trait of the African subspecies which is absconding, where the Africanized honeybee colonies abscond the hive in times when food-stores are low, unlike the European colonies which tend to die in the hive.
- Apis mellifera scutellata, classified by Lepeletier, 1836 - (African honey bee) Central and West Africa, now hybrids also in South America, Central America and the southern USA. In an effort to address concerns by Brazilian beekeepers and to increase honey production in Brazil, Warwick Kerr, a Brazilian geneticist, was asked by Brazilian Federal and State authorities in 1956 to import several pure African queens from Tanzania to Piracicaba-São Paulo State in the south of Brazil. In a mishap some queens escaped. The African queens eventually mated with local drones and produced what are now known as Africanized honey bees on the American continent. The intense struggle for survival of honey bees in sub-Saharan Africa is given as the reason that this sub-species is proactive in defending the hive, and also more likely to abandon an existing hive and swarm to a more secure location. They direct more of their energies to defensive behaviors and less of their energies to honey storage. African honey bees are leather colored, difficult to distinguish by eye from darker strains of Italian bees.
Source: Abramsona, Charles I. ; Aquinob, Italo S. ; Brain, Behavior, Evolution 2002;59:68-86) Behavioral Studies of Learning in the Africanized Honey Bee (Apis mellifera L.) web accessed Nov. 2006
- Apis mellifera monticola, classified by Smith, 1961 - High altitude mountains at elevation between 1,500 and 3,100 metres of East Africa Mt. Elgon, Mt. Kilimanjaro, Mt.Kenya, Mt.Meru
- Apis mellifera sahariensis, classified by Baldensperger, 1932 - from the Moroccan desert oases of Northwest Africa. This sub-species faces few predators other than humans and is therefore very gentle. Moreover, because of the low density of nectar-producing vegetation around the oases it colonizes, it forages up to five miles, much farther than sub-species from less arid regions. Other authorities say that while colonies of this species are not much inclined to sting when their hives are opened for inspection, they are, nevertheless, highly nervous.
- Apis mellifera intermissa, classified by von Buttel-Reepen, 1906; Maa, 1953 - Northern part of Africa in the general area of Morocco, Libya and Tunisia. These bees are totally black. They are extremely fierce but do not attack without provocation. They are industrious and hardy, but have many negative qualities that argue against their being favored in the honey or pollination industry.
- Apis mellifera major, classified by Ruttner, 1978 - from the Rif mountains of Northwest Morocco - This bee may be a brown variety of the Apis mellifera intermissa but there are also anatomic differences.
- Apis mellifera unicolor, classified by Latreille, 1804 - Madagascar
- Apis mellifera lamarckii, classified by Cockerell, 1906 - (Lamarck's honey bee) of the Nile valley of Egypt and Sudan. This mitotype can also be identified in honey bees from California. 
- Apis mellifera litorea, classified by Smith, 1961 - Low elevations of east Africa
- Apis mellifera nubica, (Nubian honey bee) of Sudan
Subspecies originating in the Middle East and Asia
- Apis mellifera meda, classified by Skorikov, 1829 - Iraq
- Apis mellifera adamii, classified by Ruttner, 1977 - Crete
- Apis mellifera anatolica, classified by Maa, 1953 - This race is typified by colonies in the central region of Anatolia in Turkey and Iraq (Range extends as far east as Armenia). It has many good characteristics but is rather unpleasant to deal with in and around the hive.
- Apis mellifera pomonella, classified by Sheppard & Meixner, 2003 - Endemic honey bees of the Tien Shan Mountains in Central Asia. This sub-species of Apis mellifera has a range that is the farthest East.
Biology, life cycle
In the temperate zone, honey bees survive winter as a colony, and the queen begins egg laying in mid to late winter, to prepare for spring. This is most likely triggered by longer day length. She is the only fertile female, and deposits all the eggs from which the other bees are produced. Except for a brief mating period when she may make several flights to mate with drones, or if she leaves in later life with a swarm to establish a new colony, the queen rarely leaves the hive after the larvae have become full grown bees. The queen deposits each egg in a cell prepared by the worker bees. The egg hatches into a small larva which is fed by nurse bees (worker bees who maintain the interior of the colony). After about a week, the larva is sealed up in its cell by the nurse bees and begins the pupal stage. After another week, it will emerge an adult bee.
For the first ten days of their lives, the female worker bees clean the hive and feed the larvae. After this, they begin building comb cells. On days 16 through 20, a worker receives nectar and pollen from older workers and stores it. After the 20th day, a worker leaves the hive and spends the remainder of its life as a forager. The population of a healthy hive in mid-summer can average between 40,000 and 80,000 bees.
Both workers and queens are fed "royal jelly" during the first three days of the larval stage. Then workers are switched to a diet of pollen and nectar or diluted honey, while those intended for queens will continue to receive royal jelly. This causes the larva to develop to the pupa stage more quickly, while being also larger and fully developed sexually. Queen breeders consider good nutrition during the larval stage to be of critical importance to the quality of the queens raised, good genetics and sufficient number of matings also being factors. During the larval and pupal stages, various parasites can attack the pupa/larva and destroy or damage it.
Queens are not raised in the typical horizontal brood cells of the honeycomb. The typical queen cell is specially constructed to be much larger, and has a vertical orientation. However, should the workers sense that the old queen is weakening, they will produce emergency cells known as supersedure cells. These cells are made from a cell with an egg or very young larva. These cells protrude from the comb. As the queen finishes her larval feeding, and pupates, she moves into a head downward position, from which she will later chew her way out of the cell. At pupation the workers cap or seal the cell. Just prior to emerging from their cells, young queens can often be heard "piping." The purpose of this sound is not yet fully understood.
Worker bees are infertile females; but in some circumstances, generally only in times of severe stress or with the loss or injury or declining health of the queen, they may lay infertile eggs, and in some subspecies these eggs may actually be fertile. However, since the worker bees are 'imperfect' (not fully sexually developed) females, they do not mate with drones. Any fertile eggs that they lay would be haploid, having only the genetic contribution of their mother, and in honey bees these haploid eggs will always develop into drones. Worker bees also secrete the wax used to build the hive, clean and maintain the hive, raise the young, guard the hive and forage for nectar and pollen.
In honey bees, the worker bees have a modified ovipositor called a stinger with which they can sting to defend the hive, but unlike other bees of any other genus (and even unlike the queens of their own species), the stinger is barbed. Contrary to popular belief, the bee will not always die soon after stinging: this is a misconception based on the fact that a bee will usually die after stinging a human or other mammal. The sting and associated venom sac are modified so as to pull free of the body once lodged (autotomy), and the sting apparatus has its own musculature and ganglion which allow it to keep delivering venom once detached. It is presumed that this complex apparatus, including the barbs on the sting, evolved specifically in response to predation by vertebrates, as the barbs do not function (and the sting apparatus does not detach) unless the sting is embedded in elastic material. Even then, the barbs do not always "catch", so a bee may occasionally pull the sting free and either fly off unharmed, or sting again.
Drone bees are the male bees of the colony. Since they do not have ovipositors, they also do not have stingers. Drone honeybees do not forage for nectar or pollen. In some species, drones are suspected of playing a contributing role in the temperature regulation of the hive. The primary purpose of a drone bee is to fertilize a new queen. Multiple drones will mate with any given queen in flight, and each drone will die immediately after mating; the process of insemination requires a lethally convulsive effort. Drone honey bees are haploid (having single, unpaired chromosomes) in their genetic structure and are descended only from their mother, the queen. They truly do not have a father. In essence, drones are the equivalent of flying gametes. In regions of temperate climate, the drones are generally expelled from the hive before winter and left to die of cold and starvation, since they are unable to forage or produce honey or take care of themselves.
The average lifespan of the queen in most subspecies is three to four years. However, there are reports that in the German/European Black Bee subspecies that was previously used for beekeeping, the queen was said to live up to 8 years. Because queens deplete their store of sperm, towards the end of their life they start laying more and more unfertilized eggs. Beekeepers therefore frequently change queens every or every other year.
The lifespan of the workers varies drastically over the year in places with an extended winter. Workers born in the spring will work hard and live only a few weeks, whereas those born in the autumn will stay inside for several months as the colony hibernates.
Honey bee queens release pheromones to regulate hive activities, and worker bees also produce pheromones for various communications (below).
Bees produce honey by collecting nectar, which is a clear liquid consisting of nearly 80% water with complex sugars. The collecting bees store the nectar in a second stomach and return to the hive where worker bees remove the nectar. The worker bees digest the raw nectar for about 30 minutes using enzymes to break up the complex sugars into simpler ones. Raw honey is then spread out in empty honeycomb cells to dry, which reduces the water content to less than 20%. When nectar is being processed, honeybees create a draft through the hive by fanning with their wings. Once dried, the cells of the honeycomb are sealed (capped) with wax to preserve the honey.
When a hive detects smoke, many bees become remarkably non aggressive. It is speculated that this is a defense mechanism; wild colonies generally live in hollow trees, and when bees detect smoke it is presumed that they prepare to evacuate from a forest fire, carrying as much food reserve as they can. In order to do this, they will go to the nearest honey storage cells and gorge on honey. In this state they are quite docile since defense from predation is relatively unimportant; saving as much as possible is the most important activity.
Thermal regulation of the Honey bee
The honey bee needs an internal body temperature of 35 °C to fly, which is also the temperature within the cluster. The brood nest needs the same temperature over a long period to develop the brood, and it is the optimal temperature for the creation of wax.
The temperature on the periphery of the cluster varies with the outside air temperature. In the winter cluster, the inside temperature is as low as 20 - 22 °C.
Honey bees are able to forage over a 30 °C range of air temperature largely because they have behavioural and physiological mechanisms for regulating the temperature of their flight muscles. From very low to very high air temperatures, the successive mechanisms are shivering before flight and stopping flight for additional shivering, passive body temperature in a comfort range that is a function of work effort, and finally active heat dissipation by evaporative cooling from regurgitated honey sac contents. The body temperatures maintained differ depending on expected foraging rewards and on caste.  The optimal air temperature for foraging is 22 - 25 °C. During flight, the rather large flight muscles create heat, which must dissipate. The honeybee uses a form of evaporative cooling to release heat through its mouth. Under hot conditions, heat from the thorax is dissipated through the head. The bee regurgitates a droplet of hot internal fluid—a "honeycrop droplet"--which immediately cools the head temperature by 10 °C.
Below 7-10 °C, bees become immobile due to the cold and above 38 °C bee activity slows due to heat. Honey bees can tolerate temperatures up to 50 °C for short periods.
Honey bee queens
Periodically, the colony determines that a new queen is needed. There are three general triggers.
- The colony becomes space-constrained because the hive is filled with honey, leaving little room for new eggs. This will trigger a swarm where the old queen will take about half the worker bees to found a new colony, leaving the new queen with the other half of worker bees to continue the old colony.
- The old queen begins to fail. This is thought to be recognized by a decrease in queen pheromones throughout the hive. This situation is called supersedure. At the end of the supersedure, the old queen is generally killed.
- The old queen dies suddenly. This is an emergency supersedure. The worker bees will find several eggs or larvae in the right age-range and attempt to develop them into queens. Emergency supersedure can generally be recognized because the queen cell is built out from a regular cell of the comb rather than hanging from the bottom of a frame.
Regardless of the trigger, the workers develop the larvae into queens by continuing to feed them royal jelly. This triggers an extended development as a pupa.
When the virgin queen emerges, she is commonly thought to seek out other queen cells and sting the infant queens within and that should two queens emerge simultaneously, they will fight to the death. Recent studies, however, have indicated that colonies of Apis mellifera may maintain two queens in as many as 10% of hives. The mechanism by which this occurs is not yet known, but it has been reported to occur more frequently in some South African subspecies of Apis mellifera. Regardless, the queen asserts her control over the worker bees through the release of a complex suite of pheromones called queen scent.
After several days of orientation within and around the hive, the young queen flies to a drone congregation point - a site near a clearing and generally about 30 feet (9.1 m) above the ground where the drones from different hives tend to congregate in a swirling aerial mass. Drones detect the presence of a queen in their congregation area by her smell, and then find her by sight and mate with her in midair (drones can be induced to mate with "dummy" queens if they have the queen pheromone applied). A queen will mate multiple times and may leave to mate several days in a row, weather permitting, until her spermatheca is full.
The queen lays all the eggs in a healthy colony. The number and pace of egg-laying is controlled by weather and availability of resources and by the characteristics of the specific race of honeybee. Honey bee queens generally begin to slow egg-laying in the early-fall and may even stop during the winter. Egg-laying will generally resume in late winter as soon as the days begin to get longer. Egg-laying generally peaks in the spring. At the height of the season, she may lay over 2500 eggs per day - more than her own body mass.
The queen fertilizes each egg as it is being laid using stored sperm from the spermatheca. The queen will occasionally not fertilize an egg. These eggs, having only half as many genes as the queen or the workers, develop into drones.
The European honey bee is the third insect, after the fruit fly and the mosquito, to have its genome mapped. According to the scientists who analysed its genetic code, the honey bee originated in Africa and spread to Europe in two ancient migrations. They have also discovered that the number of genes in the honey bees related to smell outnumber those for taste, and they have fewer genes for immunity than the fruit fly and the mosquito. The genome sequence revealed several groups of genes, particularly the genes related to circadian rhythms, were closer to vertebrates than other insects. Genes related to enzymes that control other genes were also vertebrate-like.
See also: Honey Bee Genome Sequencing Consortium
Honey bee pheromones
Honey bees use special pheromones, or chemical communication, for almost all behaviors of life. Such uses include (but are not limited to): mating, alarm, defense, orientation, kin and colony recognition, food production, and integration of colony activities. Pheromones are thus essential to honey bees for their survival.
Honey bee communication
Honey bees are an excellent animal to study with regards to behavior because they are abundant and familiar to most people. An animal that is disregarded every day has very specific behaviors that go unnoticed by the normal person. Karl von Frisch studied the behavior of honey bees with regards to communication and was awarded the Nobel Prize for physiology and medicine in 1973. Von Frisch noticed that honey bees communicate with the language of dance. Honey bees are able to direct other bees to food sources through the round dance and the waggle dance. The round dance tells the other foragers that food is within 50 meters of the hive, but it does not provide much information regarding direction. The waggle dance, which may be vertical or horizontal, provides more detail about both the distance and the direction of the located food source. It is also hypothesized that the bees rely on their olfactory sense to help locate the food source once the foragers are given directions from the dances.
Another signal for communication is the shaking signal, also known as the jerking dance, vibration dance, or vibration signal. It is a modulatory communication signal because it appears to manipulate the overall arousal or activity of behaviors. The shaking signal is most common in worker communication, but it is also evident in reproductive swarming. A worker bee vibrates its body dorsoventrally while holding another honey bee with its front legs. Jacobus Biesmeijer examined the incidence of shaking signals in a forager’s life and the conditions that led to its performance to investigate why the shaking signal is used in communication for food sources. Biesmeijer found that the experienced foragers executed 92.1% of the observed shaking signals. He also observed that 64% of the shaking signals were executed by experienced foragers after they had discovered a food source. About 71% of the shaking signal sessions occurred after the first five foraging success within one day. Then other communication signals, such as the waggle dance, were performed more often after the first five successes. Biesmeijer proved that most shakers are foragers and that the shaking signal is most often executed by foraging bees over pre-foraging bees. Beismeijer concluded that the shaking signal presents the overall message of transfer work for various activities or activity levels. Sometimes the signal serves to increase activity, when bees shake inactive bees. At other times, the signal serves as an inhibitory mechanism such as the shaking signal at the end of the day. However, the shaking signal is preferentially directed towards inactive bees. All three types of communication between honey bees are effective in their jobs with regards to foraging and task managing.
- "The general story of the communication of the distance, the situation, and the direction of a food source by the dances of the returning (honey bee) worker bee on the vertical comb of the hive, has been known in general outline from the work of Karl von Frisch in the middle 1950s."
For a discussion of bees' cognition, response to training, varieties of dance, and use of odors, see Bee learning and communication.
The honey bee is a colonial insect that is often maintained, fed, and transported by beekeepers. Honey bees do not survive individually, but rather as part of the colony. Reproduction is also accomplished at the colony level. Colonies are often referred to as superorganisms.
Honey bees collect flower nectar and convert it to honey which is stored in their hives. The nectar is transported in the stomach of the bees, and is converted to honey through the addition of various digestive enzymes, and by being stored in a 'honey cell' and then partially dehydrated. Nectar and honey provide the energy for the bees' flight muscles and for heating the hive during the winter period. Honey bees also collect pollen which supplies protein and fat for bee brood to grow. Centuries of selective breeding by humans have created honey bees that produce far more honey than the colony needs. Beekeepers, also known as "apiarists," harvest the honey.
Beekeepers often provide a place for the colony to live and to store honey. There are seven basic types of beehive: skeps, Langstroth hives, top-bar hives, box hives, log gums, D.E. hives and miller hives. All U.S. states require beekeepers to use movable frames to allow bee inspectors to check the brood for disease. This allows beekeepers to keep the Langstroth, top-bar, and D.E. hives freely, but other types of hives require special permitting, such as for museum use. The type of beehive used significantly impacts colony health and wax and honey production.
Modern hives also enable beekeepers to transport bees, moving from field to field as the crop needs pollinating and allowing the beekeeper to charge for the pollination services they provide.
In cold climates some beekeepers have kept colonies alive (with varying success) by moving them indoors for winter. While this can protect the colonies from extremes of temperature and make winter care and feeding more convenient for the beekeeper, it can increase the risk of dysentery (see the Nosema section of diseases of the honey bee) and can create an excessive buildup of carbon dioxide from the respiration of the bees. Recently, inside wintering has been refined by Canadian beekeepers, who build large barns just for wintering bees. Automated ventilation systems assist in the control of carbon dioxide build-up.
Products of the honey bee
The honey bee's primary commercial value is as a pollinator of crops. Orchards and fields have grown larger; at the same time wild pollinators have dwindled. In several areas of the world the pollination shortage is compensated by migratory beekeeping, with beekeepers supplying the hives during the crop bloom and moving them after bloom is complete. In many higher latitude locations it is difficult or impossible to winter over enough bees, or at least to have them ready for early blooming plants, so much of the migration is seasonal, with many hives wintering in warmer climates and moving to follow the bloom to higher latitudes.
As an example, in California, the pollination of almonds occurs in February, early in the growing season, before local hives have built up their populations. Almond orchards require two hives per acre (2,000 m² per hive) for maximum yield and so the pollination is highly dependent upon the importation of hives from warmer climates. Almond pollination, which occurs in February and March, is the largest managed pollination event in the world, requiring more than one third of all the managed honey bees in the United States. Massive movement of honey bee are also made for apples in New York, Michigan, and Washington. And despite the inefficiency of honey bees in pollinating blueberries, huge numbers are also moved to Maine for blueberries, because they are the only pollinators that can be relatively easily moved and concentrated for this and other monoculture crops.
Commercial beekeepers plan their movements and their wintering locations with prime reference to the pollination services they plan to perform.
Honey is the complex substance made when the nectar and sweet deposits from plants and trees are gathered, modified and stored in the honeycomb by honey bees. Honey is a complex biological mixture that consists mostly of inverted sugars, primarily glucose and fructose. It has antibacterial and antifungal properties and will not rot or ferment when stored under normal conditions. However, honey will crystallize with time. Crystallized honey is not damaged or defective in any way, for human use, but bees will automatically remove crystallized honey from their hive and discard it, since they can only use liquid honey.
Worker bees of a certain age will secrete beeswax from a series of glands on their abdomen. They use the wax to form the walls and caps of the comb. When honey is harvested, the wax can be gathered to be used in various wax products like candles and seals.