Sabtu, 28 Mei 2011

LEBAH MADU 22 - Sarang Lebah 1 - Beehive - 蜂箱

LEBAH MADU 22 - Sarang Lebah 1 - Beehive - 蜂箱

NOVA Online > Tales From the Hive > Anatomy of a Hive > Intro

Anatomy of a Hive by Peter Tyson
A honeybee hive is far more than just a buzz of activity. In fact, the social organization inside a nest rivals that in the best-run corporations, with each bee and each cell possessing a rigidly specific function. If you're unfamiliar with them, some of those functions, such as the "waggle dance," might leave you scratching your head in amazement at their sheer sophistication. Climb inside a bee's nest by clicking on the thumbnail images at left, and get a taste of the fascinating physical and social infrastructure of a hive.
 Inside a honeybee hive.
Peter Tyson is Online Producer of NOVA.

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Tales From the Hive >
Anatomy of a Hive > Colony


Swarm on branch
A colony of honeybees swarming around the unseen queen.

A single colony typically contains 20,000 to 30,000 bees. At any one time, the colony gathers nectar using several thousand foraging worker bees that descend on flower patches spread over an area as wide as 40 square miles. (During the course of a year, one colony will gather more than 260 pounds of nectar.) The patches differ in size and richness, with richness declining as a factor of the number of bees visiting it to harvest nectar. To effectively exploit the various floral resources within its range, a colony must constantly gather information about flower patches and adjust its visitation strategy accordingly.

The swarm flies
At the height of the flower season, a colony will have several thousand foragers at once on a search for nectar and pollen.

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Anatomy of a Hive > Queen


Queen in flight
A queen bee in mid-flight, preparing to mate with drones.

Workers decide which bees in the hive will become queens. It's simply a matter of the size of the cell they choose (queen cells are slightly larger) and the sugar content in the food they give the developing larvae: Food for worker larvae contains about 10 percent sugar, while that for aspiring queens holds about 35 percent sugar. Soon after becoming an adult, a newly fledged queen, which is larger than all other bees in the nest, makes several mating flights. Typically, she'll mate with 10 or more males. Since she's the only bee that will lay eggs, this ensures genetic heterogeneity in the hive. (In other words, while all bees in the hive have the same mother, they have various fathers.) After the mating flight, the queen stores millions of sperm in her body. These are good for up to three years, her potential lifespan.

Queen stings foe
A queen bee (center) stings an unborn rival to death in her brood cell.

If the queen appears to slow her pace of laying eggs or otherwise shows signs of weakening power, the workers will raise more queen larvae. When a new queen or queens emerge, the old queen leaves the hive, with a swarm of loyal offspring at her heels; she must find a new hive or die. Meanwhile, new queens are either killed while still in their brood cells, kicked out of the hive when they emerge, or battle with one another until just one queen remains. The newly crowned queen spreads pheromones via her workers to let the nest members know she's alive and well, and to suppress reproductivity among the workers.

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Foraging worker
Foraging worker bees collect both nectar and pollen to help feed the colony.

Worker bees are all female and make up about 85 percent of nest bees. They have three life stages, during which they have specific roles to fill. Young workers (1 to 12 days old) clean cells, nurse the brood, and tend the queen. Middle-aged workers (12 to 20 days old) build the comb, store nectar and pollen brought by forager bees, and ventilate the nest (see temperature). Older workers (20 days to 30 days or more, the rough life expectancy of a honeybee), are primarily foragers who supply nectar and provide the enzymes needed for converting it to honey. Flying at a speed of about 15 miles per hour, each can travel more than three and a half miles from home on a single flight. Bee researcher Thomas Seeley has likened this capability to a five-foot-tall person "flying" 375 miles, the distance from Boston to Washington, or from Berlin to Zürich.

Bee on flower
Veteran worker bees, those older than 20 days, spend most of their time foraging for nectar and pollen.

NOVA Online > Tales From the Hive > Anatomy of a Hive > Drone

New drone emerging from cell
A drone emerges from his brood cell.

The males or drones have one purpose in life: to mate with the queen. Nature has given them extra-large eyes to ensure that they do not lose sight of the queen on the mating flight. At the appropriate time, drones meet at special mating areas far from the hive, where they attempt to mate with the queen at heights of up to 100 feet off the ground. (See The Making Of for a description of how the filmmakers got around the height problem to film an in-flight mating.)

Drone hatches
The drone's extra-large eyes help ensure that he will not lose sight of the queen during the mating flight.

From birth, males have certain advantages over females (workers). While emerging workers have to climb out of their brood cells all by themselves, baby drones are helped out by nurse bees; and they don't have to do a single thing around the nest. But there are distinct disadvantages to being a male. When food supplies are low or when winter approaches, workers do not hesitate to kick drones out of the nest, where they inevitably perish. And a male who is lucky enough to score with a queen pays the ultimate price. During mating, his reproductive parts get ripped out of him, and he dies.

NOVA Online > Tales From the Hive > Anatomy of a Hive > Communication


Waggle dance
A worker does the waggle dance before an attentive crowd of foragers.

Honeybees have evolved an extraordinary form of communication known as the "waggle" dance. It is highly symbolic, separated as it is in both time and space from the activity it grew out of (discovering a nectar source) and the activity it will spur on (getting other bees to go to that nectar source).

Pollen-covered bee
When a worker discovers a good source of nectar or pollen (note the pollen spores dusting this bee's back), she will return to the hive to perform a waggle dance to let her nest mates know where it lies.

A bee performs the waggle dance when she wants to inform other bees of a nectar source she has found. The waggle occurs on a special dance floor, which is conveniently located near the entrance to facilitate quick entry and exit of foragers, and only bees with news of highly profitable sources of nectar execute the dance. Arriving back at the nest, a bee with news to share immediately proceeds to the dance floor, where other bees waiting for news gather around her. During the waggle, she dances a figure-eight pattern, with a straight "walk" in between the loops and a sporadic fluttering of her wings. The worker communicates several key pieces of information during the dance. The longer she waggles - typically bees make between one and 100 waggle runs per dance - the farther the flower patch lies from the hive, with every 75 milliseconds she prolongs the dance adding roughly another 330 feet to the distance. She shows how rich the source is by how long and/or how vigorously she dances. Perhaps most astonishingly, she indicates the direction of the source by the angle her waggle walk deviates from an imaginary straight line drawn from the dance floor to the sun at its current position. In other words, if the source lies in the exact direction of the sun, the bee will walk facing exactly straight up (remember that a hive hangs vertically). If it lies 20 degrees to the right of that imaginary line to the sun, the angle of the bee's walk will be 20 degrees to the right of vertical. Finally, the dancer shares the odor of the flowers in question with the other bees, who sample it with their antennae.
Attendees will watch only one waggle dance and only for a brief period before leaving the hive. In this way, the bee works for the good of the hive rather than for the good of herself. If she stayed for the whole dance, she would know exactly how rich the source is, for instance. But if all bees waited for the entire dance to take place, and then only went to the richest sources, the colony would not be maximizing its use of available resources. This behavior is one of many instances of how, when it comes to honeybees, natural selection operates on the level of the colony, not the individual bee.

Waggle dance
With the waggle dance, a worker communicates the distance, direction, and quality of a nectar-rich flower patch to her fellow honeybees.

Honeybees perform two other types of dance. A worker does the "shake" dance when nectar sources are so rich that more foragers are needed. A worker arriving back from a foraging run will move throughout the hive and shake her abdomen back and forth before a non-foraging worker for one to two seconds before moving onto more non-foragers at the rate of between one and 20 bees per minute. The shake dance encourages these non-foragers to make their way to the waggle dance floor. Finally, workers do the "tremble" dance when foragers have brought so much nectar back to the hive that more bees are needed to process the nectar into honey. Walking slowly around the nest, the dancer quivers her legs, causing her body to tremble forward and backward and from side to side. Lasting sometimes more than an hour, the tremble dance stimulates additional bees to begin processing nectar.

NOVA Online > Tales From the Hive > Anatomy of a Hive > Food


Putting honey away
After receiving a regurgitated stomach-full of nectar from another bee, a middle-aged worker deposits it into a honey cell.

Foraging bees store nectar, the colony's principal source of carbohydrates, in the so-called honey stomach in their abdomens. When they return to the hive, they regurgitate the nectar to middle-aged workers, which either distribute the nectar for immediate consumption or process it into honey and store it in special honey cells. Sometimes foragers bring water rather than nectar. Nurse bees—those tending the brood of unborn workers—will use the water either to dilute honey to feed the brood or, on hot days, to cool the hive through evaporation (see temperature).

Bee on flower with full pollen
A honeybee with a full pollen basket visible on her hind left leg.

Returning foragers also bring pollen, which they carry in special pollen "baskets" on their hind legs. Pollen provides colony members with vital amino acids, vitamins, and fats. It is stored in pollen cells near the brood cells, so it is readily available to nurse bees, which fashion the pollen into a kind of bread for supplying nourishment to developing larvae. 

NOVA Online > Tales From the Hive > Anatomy of a Hive > Defense


Guards attack wasp
Guard bees attack an invading wasp.

Bees have a much greater armory of defenses against attacks than simply their stingers. For external threats, the bees rely, first and foremost, on their protective nest. Guard bees patrolling the single, tight entrance quickly attack intruders, and when necessary, will join a massive counterattack synchronized by the release of alarm pheromones. For internal threats, bees have a bevy of defenses as well. When first building the hive, they varnish the interior walls with floral herbicides and fungicides. They bear a colony-specific odor that helps them distinguish between colony members and intruders. The honey they produce has biocidal properties that inhibit the microbial spoilage of this precious resource. And so-called "undertaker" bees are so assiduous about removing the carcasses of their dead fellows that, while a nest will suffer about 100 deaths of its members every day, it rarely will contain more than one or two dead adults at any one time.

Bees at wooden entrance to home
Guard bees patrol the entrance to a hive.

NOVA Online > Tales From the Hive > Anatomy of a Hive > Nest


Tree opening to hive
Bees investigate the opening of a new nest site in a hollow tree trunk.

When investigating a potential site for a new hive, scout bees carefully check the cavity to ensure it meets certain specifications. It must be large enough to hold a volume of not less than about six and a half gallons. It must have a small entrance that has a maximum diameter of about one and a half inches and that lies near the base to facilitate removal of waste. Finally, it should face south for warmth, and it should lie high off the ground to protect against predators. Once they have identified a suitable site, honeybees scrape off any loose wood or other debris and coat the interior surface with propolis, or dried tree resin. They then starting generating beeswax to build the combs.

Cluster of bees
If this swarming honeybee colony cannot find a good site for a new hive soon, it will perish.

NOVA Online > Tales From the Hive > Anatomy of a Hive > Comb


Honeybees secrete wax from their abdomens to build the comb.

Middle-aged worker bees are responsible for constructing the combs. Using wax secreted from their abdomens, they build the combs downward from the top of the hive. They attach each comb, which consists of two layers of horizontal, hexagonally shaped cells, to the roof and walls, leaving small passageways along the walls to allow movement between combs. In a typical nest, the combs will have cells for storing honey up top, followed by a layer of pollen-storage cells, and then beneath that the brood cells for workers and, off to one side, drones. Finally, at the bottom or off by themselves to the sides hang the peanut-shaped cells that house infant queens.

Larvae in cells
Each brood cell contains a single larva of a honeybee.

A natural nest will have roughly 100,000 cells in half a dozen combs, whose total surface area will be about 27 square feet. It takes more than two and a half pounds of beeswax to create such a structure (not to mention about 15 pounds of honey to synthesize that wax). A colony needs those 100,000 cells to store the more than 40 pounds of honey it requires to survive a typical temperate winter and to provide nursery space for the roughly 20,000 immatures that the overwintering bees will rear in the spring.

NOVA Online > Tales From the Hive > Anatomy of a Hive > Temperature


Bees tending cells
Through a variety of means, honeybees keep the nest temperature high even during winter months.

In winter, honeybees don't become dormant like many other insects, but rather create a warm microclimate inside the hive and subsist on the stored honey. The bees warm themselves and the nest as a whole by exercising their flight wings - like revving the engine in neutral. They retain this precious heat by allowing only small openings in the nest, by using plant resins and gums to seal holes and cracks, and by clustering into a round mass of bees. By so doing, they can keep the temperature of bees at the outermost limits of the cluster above 50°F, the honeybee's lower lethal limit. To maintain such a microclimate, the colony must consume more than two pounds of honey a week throughout the winter, hence the strenuous collection of nectar during the warmer months.

Bee collecting water
Fewer than one percent of foragers will collect water, which they either give to nurse bees to dilute honey for feeding the brood or spread over the comb when it's too hot.

From late winter to early autumn, bees keep the temperature in the hive's nursery between about 91°F and 97°F to ensure proper development of the young. They rarely allow the temperature to vary more than 2°F in the course of a day. On steamy days, they cool the nest by fanning their wings or by spreading water on the comb to remove heat through evaporation.

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