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08‏/03‏/2010

Colony members ( أفراد طائفة النحل)


Every honeybee colony is a family, consisting of a single fertile female, the queen, which is the mother of the colony; a large number (ranging from several thousand to tens of thousands) of infertile females, the workers; and, at certain times of the year, several hundred male drones. Taken together, these three categories are referred to as castes.
(1) The Queen
Being the sole member of the female reproductive caste, the queen is indispensable for the survival of the colony. A mated queen serves the colony in two essential functions: laying fertilized and unfertilized eggs, and secreting substances known as pheromones, required for the stability of the colony's social order.
Within a few days of having mated in mid-air with about ten drones, the queen begins to lay eggs, and continues to do so until she is physiologically exhausted. The larvae of female bees (queens and workers) will hatch from the fertilized eggs, while the unfertilized eggs yield drone larvae. Factors determining whether fertilized or unfertilized eggs are to be laid include the size of the cells in the comb and the mechanism underlying the functioning of the queen's reproductive organs. During the mating process, the queen stores sperm from the drones in a storage organ, the spermatheca, within her abdomen. By controlling the opening and closing of the spermatheca, the queen can allow sperm cells to fertilize her eggs or prevent them from doing so. The fertilized eggs are deposited in small worker cells, while the unfertilized eggs are laid in the larger drone cells: the queen can determine cell size and cleanliness by passing her head into the cell and using her front legs to measure its internal width.
Healthy, sufficiently mated A. mellifera queens can lay as many as 1500 to 2000 eggs a day, provided that the colony is strong, that the queen is sufficiently fed and that there is sufficient empty comb space to accommodate the eggs. The workers partially control the queen's egg-laying by regulating the amount of food fed to the queen and by their preparation of empty cells; they also cannibalize the eggs when a food shortage occurs.
Worker bees recognize their queen not by her physical structure but by her scent, given off by the pheromones she secretes. These pheromones, which consist of about 30 organic compounds, have both direct and indirect effects on the colony's social behaviour. During the nuptial flight, they serve as sex attractants, drawing the drones to the queen. Inside the hive, they assist in stabilizing the colony: the workers are aware of the queen's whereabouts by the presence or absence of pheromones. In A. mellifera colonies, some workers act as "messengers" in distributing the pheromones they obtain from direct contact with the queen to other workers within the hive. Under certain circumstances, the presence within the hive of pheromones will inhibit the untimely construction of queen cells: they also inhibit the development of the workers' ovaries, and during swarming they exercise a direct influence on swarm stabilization.
Pheromone communications within the colony constitute one of the most important components of the social life of all honeybee species. Since older queens secrete less pheromones as well as laying less well - than queens in their prime age, and although a queen can live for several years before being superseded by a younger one, professional beekeepers often requeen their colonies every one or two years, in order always to have queens at their maximum biological efficiency.
(2) The Drones
The drones are the male members of the honeybee society reared by the colony shortly before the swarming season begins. As already stated, several hundred drones may be reared by the colony, emerging from unfertilized eggs the queen lays in larger brood cells. In queenless colonies, workers whose ovaries have developed as a result of the lack of inhibiting action by the queen's pheromones can also lay eggs which, being unfertilized because the worker is unmated, also yield drones.
Drones possess no food-gathering apparatus: their sole biological function is to mate with queens. During the mating season, they are well fed by the workers before taking flight. A drone may make from 4 to 6 flights a day, but a smaller number is not uncommon. Drones from neighbouring colonies all fly to a place known as the "drone congregation area", where mating takes place. To ensure successful mating, several thousands of drones must be in the area, although the queen will mate with only about ten. The drone dies shortly after copulation.
When the mating season is nearing its end, the colony reduces its drone-rearing, and when the season is over, the rearing of drones ceases completely. The drones remaining in the hive gradually die of old age, negligence by the worker bees or starvation, or they may simply be expelled from the hive.
(3) The Workers
The workers are an infertile caste of female bees, developed from fertilized eggs. They are suited by their physiological and anatomical features to perform virtually all kinds of chores except reproduction, to increase the chances of the colony's survival. Factors determining the type of task to be executed by a worker include its physiological and anatomical state of readiness, and environmental stimuli, as well as the requirements of the colony to have a particular job done at a particular time.
Soon after emerging from its cell, a young worker receives food, in the form of either nectar or honey, from mature workers, and also helps herself to honey and pollen she finds in the colony's storage cells. In the first few days after she emerges, she is too weak to do anything except inspect and clean empty cells in preparation for food storage by the colony or egg-laying by the queen. During this period she consumes relatively large amounts of honey and pollen, and this directly affects the development of her hypopharyngeal and wax glands.
The secretion from this "nurse bee"'s hypopharyngeal glands, rich in fat and protein, is fed to the larvae, those of all ages in queen cells receiving large quantities; for this reason it is referred to as "royal jelly". Larvae in worker and drone cells receive this special diet only during the first days after hatching; during their later larval life they are fed on a mixture of honey and pollen.
At about the same time as the hypopharyngeal glands of the nurse bee develop, or shortly afterward, four pairs of wax glands, located below her abdominal segments also develop, under the stimulation of consumption of large amounts of honey. From these glands she secretes flakes of whitish wax, which are manipulated by worker bees, using their mandibles, in the process of comb construction and repair and in capping cells.
Under normal conditions, a worker bee is physiologically exhausted from the tasks of secreting royal jelly and wax when she reaches the age of about 14 to 18 days. A few days after this period are spent packing pollen in storage cells, the mouth-to-mouth retrieval of nectar from returning foragers, and occasionally guarding the hive entrance. When she is about three weeks old she ceases to be a "house bee" and becomes a "field bee". At this stage her flight muscles are sufficiently developed, and after orientation flights which enable her to locate the hive in relation to surrounding landmarks, she collects nectar, pollen, water and propolis and carries them back to the hive until she dies.
As already stated, physiological readiness is not the only factor exerting a direct influence on a worker to perform any specific task: environmental stimuli, the condition of the hive, and the colony's immediate requirements are among other factors regulating the type of work to be carried out and the number of bees to be involved in each task. When a colony is running out of space to accommodate brood and food stores, for example, or when combs have been damaged or destroyed, many workers will undertake the task of comb construction and repair; older workers who have already passed beyond the wax-secretion stage can, by consuming large quantities of honey or sugar syrup, reactivate their wax glands and participate in the construction work. Again, when a colony requires a relatively large population of nurse bees to tend the growing number of brood, the duration of royal jelly secretion by the existing nurse bees can be prolonged, provided that the colony has an ample supply of honey and pollen for them to consume. On the other hand, during a heavy honeyflow season younger workers can easily be recruited for foraging as field bees to increase the colony's food-gathering capacity
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