Bees

 

Bees

Honey bees (or honeybees) are bees of the genus Apis, primarily distinguished by the production and storage of honey and the construction of perennial, colonial nests from wax. Honey bees are the only extant members of the tribe Apini, all in the genus Apis. Currently, only seven species of honey bee are recognized, with a total of 44 subspecies, though historically, from six to 11 species have been recognised. Honey bees represent only a small fraction of the roughly 20,000 known species of bees. Some other types of related bees produce and store honey, but only members of the genus Apis are true honey bees.

The study of honey bees is known as apiology.

Different bees:

Micrapis

Apis florea and Apis andreniformis are small honey bees of southern and southeastern Asia. They make very small, exposed nests in trees and shrubs. Their stings are often incapable of penetrating human skin, so the hive and swarms can be handled with minimal protection.

Megapis

One species is recognized in the subgenus Megapis. It usually builds single or a few exposed combs on high tree limbs, on cliffs, and sometimes on buildings. They can be very fierce. Periodically robbed of their honey by human “honey hunters”, colonies are easily capable of stinging a human being to death if provoked.

  • Apis dorsata, the giant honey bee, is native and widespread across most of South and Southeast Asia.
    • Apis dorsata binghami, the Indonesian honey bee, is classified as the Indonesian subspecies of the giant honey bee or a distinct species; in the latter case, A. d. breviligula and/or other lineages would probably also have to be considered species.
    • Apis dorsata laboriosa, the Himalayan honey bee, was initially described as a distinct species. Later, it was included in A. dorsata as a subspecies based on the biological species concept, though authors applying a genetic species concept have suggested it should be considered a species. Essentially restricted to the Himalayas, it differs little from the giant honey bee in appearance, but has extensive behavioral adaptations that enable it to nest in the open at high altitudes despite low ambient temperatures. It is the largest living honey bee.

Apis

The eastern species include three or four species. The reddish Koschevnikov’s bee (Apis koschevnikovi) from Borneo is well distinct; it probably derives from the first colonization of the island by cave-nesting honey bees. Apis cerana, the eastern honey bee proper, is the traditional honey bee of southern and eastern Asia, kept in hives in a similar fashion to A. mellifera, though on a much smaller and regionalised scale. It has not been possible yet to resolve its relationship to the Bornean A. c. nuluensis and Apis nigrocincta from thePhilippines to satisfaction; the most recent hypothesis is that these are indeed distinct species, but that A. cerana is still paraphyletic, consisting of several good species.

The European honey bee originated from eastern Africa. This bee is pictured in Tanzania.

A. mellifera, the most common domesticated species, was the third insect to have its genomemapped. It seems to have originated in eastern tropical Africa and spread from there to Northern Europe and eastwards into Asia to the Tien Shan range. It is variously called the European, western or common honey bee in different parts of the world. Many subspecieshave adapted to the local geographic and climatic environments; in addition, hybrid strains, such as the Buckfast bee, have been bred. Behavior, color, and anatomy can be quite different from one subspecies or even strain to another.

Apis mellifera is not native to the Americas, so was not present upon the arrival of the European explorers and colonists. However, other native bee species were kept and traded by indigenous peoples. In 1622, European colonists brought the dark bee (A. m. mellifera) to the Americas, followed later by Italian bees (A. m. ligustica) and others. Many of the crops that depend on honey bees for pollination have also been imported since colonial times. Escaped swarms (known as “wild” bees, but actually feral) spread rapidly as far as the Great Plains, usually preceding the colonists. Honey bees did not naturally cross the Rocky Mountains; they were transported by the Mormon pioneers to Utah in the late 1840s, and by ship to California in the early 1850s.

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Life cycle

As in a few other types of eusocial bees, a colony generally contains one queen bee, a fertile female; seasonally up to a few thousand drone bees or fertile males; and a large seasonally variable population of sterile female worker bees. Details vary among the different species of honey bees, but common features include:

1. Eggs are laid singly in a cell in a wax honeycomb, produced and shaped by the worker bees. Using her spermatheca, the queen actually can choose to fertilize the egg she is laying, usually depending on into which cell she is laying. Drones develop from unfertilised eggs and are haploid, while females (queens and worker bees) develop from fertilised eggs and are diploid. Larvae are initially fed with royal jellyproduced by worker bees, later switching to honey and pollen. The exception is a larva fed solely on royal jelly, which will develop into a queen bee. The larva undergoes several moultings before spinning a cocoon within the cell, and pupating.

2. Young worker bees clean the hive and feed the larvae. When their royal jelly-producing glands begin to atrophy, they begin building comb cells. They progress to other within-colony tasks as they become older, such as receiving nectar and pollen from foragers, and guarding the hive. Later still, a worker takes her first orientation flights and finally leaves the hive and typically spends the remainder of her life as a forager.

3. Worker bees cooperate to find food and use a pattern of “dancing” (known as thebee dance or waggle dance) to communicate information about resources with each other; this dance varies from species to species, but all living species of Apis show some form of the behavior. If the resources are very close to the hive, they may also show a less specific dance commonly known as the “round dance”.

4. Honey bees also do tremble dances, which recruit receiver bees to collect nectar from returning foragers.

5. Virgin queens go on mating flights away from their home colony to a drone congregation area, and mate with multiple drones before returning. The drones die in the act of mating. Queen honey bees do not mate with drones from their home colony.

6. Colonies are established not by solitary queens, as in most bees, but by groups known as “swarms”, which consist of a mated queen and a large contingent of worker bees. This group moves en masse to a nest site scouted by worker bees beforehand. Once they arrive, they immediately build a new wax comb and begin to raise new worker brood. This type of nest founding is not seen in any other living bee genus, though several groups of vespid wasps also found new nests by swarming (sometimes including multiple queens). Also, stingless bees will start new nests with large numbers of worker bees, but the nest is constructed before a queen is escorted to the site, and this worker force is not a true “swarm”.

Sexes and castes

The two sexes of honey bee are: females (workers and queens) and males (or drones). A caste is a different form, morphologically or reproductively, within the same sex of a species. In sum, the three types of honey bees are drones, workers, and queens, and two female castes: queens and workers.

Drones

Males or drones are typically haploid, having only one set of chromosomes. They are produced by the queen if she chooses not to fertilize an egg; or by an unfertilized laying worker. Diploid drones may be produced if an egg is fertilized but is homozygous for the sex-determination allele. Drones take 24 days to develop and may be produced from summer through autumn. Drones have large eyes used to find queens during mating flights. Drones do not have a sting.

Workers

Workers are female bees and have two sets of chromosomes. They are produced from an egg that the queen has selectively fertilized from stored sperm. Workers typically develop in 21 days. A typical colony may contain as many as 60,000 worker bees. Workers show a wider range of behaviors than either queens or drones. Their duties change upon the age of the bee in the following order (beginning with cleaning out their own cell after eating through their capped brood cell): feed brood, receive nectar, clean hive, guard duty, and foraging. Some workers engage in other specialized behaviors, such as “undertaking” (removing corpses of their nestmates from inside the hive).

Workers have morphological specializations, including the corbiculum or pollen basket, abdominal glands that produce beeswax, brood-feeding glands, and barbs on the sting. Under certain conditions (such as, if the colony becomes queenless), a worker may develop ovaries.

Queens

Queen honey bees, like workers, are female. They are created at the decision of the worker bees by feeding a larva only royal jelly throughout its development, rather than switching from royal jelly to pollen once the larva grows past a certain size. Queens are produced in oversized cells and develop in only 16 days. Queens have a different morphology and behavior from worker bees. In addition to the greater size of the queen, she has a functional set of ovaries, and a spermatheca, which stores and maintains sperm after she has mated. The sting of queens is not barbed like a worker’s sting, and queens lack the glands that produce beeswax. Once mated, queens may lay up to 2,000 eggs per day. They produce a variety of pheromones that regulate behavior of workers, and helps swarms track the queen’s place during the migratory phase.

Defense

Apis cerana japonica forming a ball around two hornets: The body heat trapped by the ball will overheat and kill the hornets.

All honey bees live in colonies where the workers sting intruders as a form of defense, and alarmed bees release a pheromonethat stimulates the attack response in other bees. The different species of honey bees are distinguished from all other bee species (and virtually all other Hymenoptera) by the possession of small barbs on the sting, but these barbs are found only in the worker bees. The sting and associated venom sac of honey bees are also modified 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. The worker dies after the sting becomes lodged and is subsequently torn loose from the bee’s abdomen.

This complex apparatus, including the barbs on the sting, is thought to have evolved specifically in response to predation by vertebrates, as the barbs do not usually function (and the sting apparatus does not detach) unless the sting is embedded in fleshy tissue. While the sting can also penetrate the membranes between joints in the exoskeleton of other insects (and is used in fights between queens), in the case of Apis cerana japonica, defense against larger insects such as predatory wasps (e.g.Asian giant hornet) is usually performed by surrounding the intruder with a mass of defending worker bees, which vibrate their muscles vigorously to raise the temperature of the intruder to a lethal level. Previously, heat alone was thought to be responsible for killing intruding wasps, but recent experiments have demonstrated the increased temperature in combination with increased carbon dioxide levels within the ball produce the lethal effect. This phenomenon is also used to kill a queen perceived as intruding or defective, an action known to beekeepers as ‘balling the queen’, named for the ball of bees formed.

In the case of those honey bee species with open combs (e.g., A. dorsata), would-be predators are given a warning signal that takes the form of a “Mexican wave” that spreads as a ripple across a layer of bees densely packed on the surface of the comb when a threat is perceived, and consists of bees momentarily arching their bodies and flicking their wings.

Communication

Honey bees are known to communicate through many different chemicals and odors, as is common in insects, but also using specific behaviours that convey information about the quality and type of resources in the environment, and where these resources are located. The details of the signalling being used vary from species to species; for example, the two smallest species, Apis andreniformis and A. florea, dance on the upper surface of the comb, which is horizontal (not vertical, as in other species), and worker bees orient the dance in the actual compass direction of the resource to which they are recruiting.

Apis mellifera carnica honey bees use their antennae asymmetrically for social interactions with a strong lateral preference to use their right antenna.

*Photos took from our organic garden.

For more informations about bees and the importance that they have in the ecosystem read:

http://giupipita.wordpress.com/2008/11/28/muoiono-le-api-muore-il-mondo

http://www.ccpollen.com/the-importance-of-bees.html

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