Bee

? Bees
Osmia ribifloris
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Hymenoptera Suborder: Apocrita Superfamily: Apoidea
Families
Andrenidae Apidae Colletidae Halictidae Heterogynaidae Megachilidae Melittidae Oxaeidae Stenotritidae

Bees (Apoidea superfamily) are flying insects, closely related to wasps and ants. They are adapted for feeding on nectar and pollen, the former primarily as an energy source, and the latter primarily for protein and other nutrients. Most pollen is used for food for the brood.

Bees have a long proboscis that enables them to obtain the nectar from flowers. Bees have antennae made up of thirteen segments in males and twelve in females. They have two pairs of wings, the back pair being the smaller of the two.

Bees play an important role in pollinating flowering plants, and are called pollinators. Bees may focus on gathering nectar or on gathering pollen, depending on their greater need at the time. Bees gathering nectar may accomplish pollination, but bees that are deliberately gathering pollen are more efficient pollinators. It is estimated that one third of the human food supply depends on insect pollination, most of this accomplished by bees.

Bees are fuzzy and carry an electrostatic charge, thus aiding in the adherence of pollen. Bees periodically stop foraging and groom themselves to pack the pollen into specialized pollen baskets which are on the legs of honeybees and some other species, and on the ventral abdomen on other species.

Bees are extremely important as pollinators in agriculture, with contract pollination having overtaken the role of honey production for beekeepers in many countries. Monoculture and pollinator decline have increasingly caused honeybee keepers to become migratory so that bees can be concentrated in areas of pollination need at the appropriate season. Many other species of bees are increasingly cultured and used to meet agricultural pollination need. Bees also play a major, though not always understood, role in providing food for birds and wildlife. Many of these bees survive in refuge in wild areas away from agricultural spraying, only to be poisoned in massive spray programs for mosquitoes, gypsy moths, or other pest insects.

There are over 16,000 described species, and possibly around 30,000 species in total. Many species are poorly known. The smallest bee is a dwarf bee (Trigona minima) and it is about 2.1 mm (5/64") long. The largest bee in the world is the Megachile pluto, which can be as large as 39 mm (1.5").

Eusocial and quasisocial bees

Bees may be solitary, or may live in various sorts of communities. The most advanced of these are eusocial colonies, found among the honeybees and stingless bees. Sociality is believed to have evolved separately in different groups of bees.

Eusocial bees live in colonies, each of which has a single queen, together with workers and drones. When humans provide a home for a colony, the structure is called a hive. A hive can typically contain up to about 40,000 individual bees at their annual peak, which occurs in the spring, but usually have fewer.

Visiting flowers is a dangerous occupation, with very high mortality rates. Many assassin bugs and crab spiders hide in flowers to capture unwary bees. Others are lost to birds in flight. Insecticides used on blooming plants can kill large numbers of bees, both by direct poisoning and by contaminating their food supply. A honeybee queen may lay 2000 eggs per day during spring buildup, but she also must lay 1000 to 1500 eggs per day during the foraging season, simply to replace daily casualties.

Bumblebees (Bombus terrestris, B. pratorum, et al.) are referred to as quasisocial because the queen bee is typically able to survive on her own for at least a short time (unlike queens in eusocial species who must be cared for at all times). Bumblebee colonies typically have from 50 to 200 individual bees at peak population, which occurs in mid to late summer.

The population value of bees depends partly on the individual efficiency of the bees, but also on the population. Thus, while bumblebees have been found to be about ten times more efficient pollinators on cucurbits, the total efficiency of a colony of honeybees is much greater, due to greater numbers. Likewise, during early spring orchard blossoms, bumblebee populations are limited to only a few queens, thus they are not significant pollinators of early fruit.

The life cycle of bumblebees begins in the spring when the queen bee rises from hibernation. At this time the queen bee is the one who does all the work as there are no worker bees to do the work yet. She searches for a place to build her nest and she builds the honeypots. She also does the foraging to collect nectar and pollen. Bumblebee colonies die off in the autumn, after raising a last generation of queens, which survive individually. Interestingly bumblebee queens sometimes seek winter safety in honeybee hives, where they are sometimes found dead in the spring by beekeepers, presumably stung to death by the honeybees. It is not known whether any succeed in winter survival in such an environment.

With honeybees, which survive winter as a colony, 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 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 (depending on species), the larva is sealed up in its cell by the nurse bees and begins the pupal stage. After another week (again, depending on species), it will emerge an adult bee.

The larvae and pupae in a frame of honeycomb are referred to as frames of brood and are often sold (with adhering bees) by beekeepers to other beekeepers to start new beehives.

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 always raised in the typical horizontal brood cells of the honeycomb. The typical queen cell is specially constructed to be much larger, and have a vertical orientation. However, should the workers sense that the old queen is weakening, they will produce emergency cells known as supercedre cells. These cells are made from a cell with a 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." This is considered likely to be a challenge to other queens for battle.

Worker bees are infertile females, however in some circumstances they may lay infertile eggs. Worker bees 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 honeybees, the worker bees have a modified ovipositor called a stinger with which they can sting to defend the hive. 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 always die shortly after stinging a mammal; however, the stinger evolved primarily for inter-bee combat.

Drone bees are the male bees of the colony. Drone honeybees do not forage for nectar or pollen. The primary purpose of a drone bee is to fertilize a new queen. Drones mate with the queen in flight. They die immediately after mating.

In some species, drones are suspected of playing a contributing role in the temperature regulation of the hive. Drone bees have no stinger, since a stinger is actually a modified ovipositor.

Queens live for up to three years, while workers have an average life of only three months (during the foraging season, but longer in places with extended winters).

Honeybee queens release pheromones to regulate hive activities, and worker bees also produce pheromones for various communications.

By collecting nectar from flowers, bees produce honey, 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.

Honey itself is so sweet that bacteria cannot grow on it, and dry enough that it does not support yeasts. Anaerobic bacteria may be present and survive in spore form in honey, however, as well as anywhere else in common environments. Honey (or any other sweetener) which is diluted by the non-acidic digestive fluids of infants, can support the transition of botulism bacteria from the spore form to the actively growing form which produces a toxin. When infants are weaned to solid foods, their digestive system becomes acidic enough to prevent such growth and poisoning. No sweeteners should be given to infants prior to weaning.

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 this state, defense from predation is relatively unimportant; saving as much as possible is the most important activity.

Honeybee Queens

Periodically, the colony determines that a new queen is needed. There are three general triggers.

1. 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.
2. The old queen begins to fail. This is thought to be recognized by a decrease in queen pheremones throughout the hive. This situation is called supersedure. At the end of the supersedure, the old queen is generally killed.
3. 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 may maintain two queens in as many as 10% of hives. The mechanism by which this occurs is not yet known. Regardless, the queen asserts her control over the worker bees through the release of a complex suite of pheremons 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 above the ground where the drones from different hives tend to congregate. Drones find the queen by site and mate with her in midair. After mating, the drone dies. A queen will mate multiple times and may return several days in a row, weather permitting, until her spermathrecea 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. Honeybees 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 spermathrecea. 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.

Honeybee pheromones

Honeybees 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 honeybees for their survival.

Solitary and communal bees

Other species of bee such as the carpenter bee, Orchard Mason bee (Osmia lignaria) and the hornfaced bee (Osmia cornifrons) are solitary in the sense that every female is fertile. There are no worker bees for these species. Solitary bees typically produce neither honey nor beeswax. They are immune from acarine and varroa mites, but have their own unique parasites, pests and diseases. (See diseases of the honeybee.)

Solitary bees are important pollinators, as pollen is gathered for provisioning the nests with food for their brood. Often it is mixed with nectar to form a paste-like consistancey. Many solitary bees have very advanced types of pollen carry structures on their bodies. Most solitary bees are wild, with a few species being increasingly cultured for pollination.

Solitary bees are often specialists, in that they only visit one or more species of plant (unlike honeybees and bumblebees which are generalists). In some cases only one species of bee can pollinate a plant species, and some plants are endangered because their pollinator is dying off.

Solitary bees create nests in hollow reeds, bored holes in wood, or in tunnels in the ground. The female typically creates a compartment with an egg and some provisions for the resulting larva, then seals it off. A nest may consist of numerous compartments, usually the last (the closest to the entrance) being eggs that will become males. The adult does not care for the brood, and usually dies after making one or more nests. The males emerge first and are ready for mating when the females emerge. Providing nest boxes for solitary bees is increasingly popular for gardeners. Solitary bees are usually stingless or very unlikely to sting.

While solitary females each make individual nests, some species are gregarious, preferring to make nests near others of the same species, giving the appearance to the causual observer that they are social.

Cleptoparasitic bees

Cleptoparasitic bees, commonly referred to as "cuckoo bees" because their behaviour is similar to that of cuckoo birds, occur in several bee families. Females of these bees lack pollen-collecting structures and do not construct their own nests. Rather, they enter the nests of pollen-collecting species, and lay their eggs in cells already provisioned by the host bee. When the cuckoo bee larva hatches, it consumes the host larva's pollen ball, and sometimes the host larva itself.

Some cleptoparasitic bees are closely related to, and resemble, their hosts (i.e., the genus Psithyrus, which is a nest parasite of bumble bees in the genus Bombus). Others parasitize dissimilar bees in different families, like Townsendiella, a nomadine anthophorid which is a nest parasite of the melittid Hesperapis.

Communication

"The general story of the communication of the distance, the situation, and the direction of a food source by the dances of the returning (honeybee) 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."