The workers and their duties

 

Workers are the smallest and most numerous of the bees, constituting over 98% of the colony’s population. One colony, as has been seen, may have as many as 80 000 workers, but 50 000 is a more common maximum.

Although they never mate, the workers possess organs necessary for carrying out the many duties essential to the wellbeing of the colony. They have a longer tongue than the queen and drones, and thus are well fitted for sucking nectar from flowers. They have large honey stomachs to carry the nectar from the field to the hive; they have pollen baskets on their third pair of legs to transport the pollen to the hive. Glands in their head produce royal jelly as food for the larvae and glands in their thorax secrete enzymes necessary for ripening honey. Four sets of wax glands, situated inside the last four ventral segments of the abdomen, produce wax for comb construction. A well-developed sting permits them to defend the colony very efficiently.

The kind of work performed by the worker depends largely upon her age. The first three weeks of her adult life, during which she is referred to as a house bee, are devoted to activities within the hive, while the remainder are devoted to field work, so that she is called a field bee.

Duties of the house bee

The duties of a house bee are –

a) cleaning the hive and the comb
b) feeding the brood
c) caring for the queen
d) making orientation flights
e) comb building
f) ventilating the hive
g) packing pollen, water, nectar or honey into the combs
h) executions
i) guard duty

Cleaning

The first activity of the worker bee on reaching maturity is to clean herself. She removes all unnecessary particles, grooms herself immediately and then crawls out of her cell. She takes in food and then starts cleaning the brood cells, employing both tongue and mandibles. The comb cells are cleaned to receive eggs laid by the queen who, before laying, examines the comb cell to satisfy herself that it has been properly cleaned. If she finds a cell that is not properly cleaned, she quickly rejects it. Other duties which may occasionally be necessary include removing dead intruders or dead bees from the hive, and removing debris and other objectionable material. Anything that is too large to carry is often dragged along and pushed outside, while dead snakes, wax moths or other carcasses too heavy to transport are encased with propolis brought in by field bees.

Feeding the brood

After three to five days, the worker bee starts to feed the brood. At this stage she is called a nurse bee. At first she feeds larvae more than three days old with a mixture of honey or nectar, pollen, small quantities of bee milk and some water. After a few days, she starts to feed the younger larvae (1-3 days old) exclusively on bee milk, which she produces in brood-food glands, also called milk glands or hypopharyngeal glands, located in her head.

Caring for the queen

The next work undertaken by the young worker is to provide for the needs of the queen bee. Whenever the queen needs food, she calls for it by stretching out her proboscis towards the mandible or mouth of the nearest worker. The workers are always anxious to satisfy her needs and make a circle or semi-circle around her. The queen contacts the nearest worker, and if she does not get as much as she needs, she approaches the next. This continues until all her demands are met. It is also the duty of the nurse bees to bathe her with their tongues and mandibles and to carry away her faeces.

Orientation flight

The orientation flight is not so much a house duty as an exercise for the young worker. She must learn how to fly, and she must know the vicinity, especially the location of the hive. She therefore first makes some short flights in front of the hive and in the immediate vicinity to acquaint herself with the environment, so that when in the near future she goes out to forage, she will be able to find her way back home.

Comb building

Comb building provides the needed “rooms” in the hive, in the form of hexagonal cells, for two main purposes: storing food and rearing brood. Beeswax, the material for the construction of comb, is secreted by the worker’s wax glands, which are best developed and productive when she is 12-18 days old. The wax, which emerges from the glands as a liquid, hardens quickly and appears in the form of oval flakes similar to small fish scales, protruding from between the last four overlapping abdominal segments on the under-side of the worker’s body. As we have already seen, the bee must consume large amounts of food (honey and nectar) to produce these wax flakes.

Bees engaged in building combs usually hang themselves in festoons at or near the site of the building operation. There they hang quietly while their digestive organs transform the contents of their honey sacs into energy and beeswax. The wax is removed with the spines of the hind legs and is then manipulated with the mandibles to build the comb cells. Capping of comb cells is also the duty of comb builders.

Ventilating the hive

Temperature control is one of the important duties of the house bee. When the temperature is low, bees cluster to generate heat for themselves, but when it is high, some of them have to fan their wings to circulate air throughout the hive. The right temperature required is between 33° and 36°C, while the brood chamber requires a constant heat of 35°. Honey has to be cured in order to ripen, and this also requires the help of circulating air. According to Crane, 12 fanning bees positioned across a hive entrance 25 cm wide can produce an air flow amounting to 50-60 litres per minute. This fanning can go on day and night during the honey-flow season. The phenomenon is always at its peak in October in the high savannah and forest zones of Vest Africa.

Honey conversion and packing

It takes several bees to produce honey. No single honeybee completes the whole process. The forager brings a load of nectar to the hive and transfers it to a house bee, who proceeds to the empty or uncrowded part of the hive, where she rests and exposes the nectar to the air being fanned by the fanning bees. The air circulation helps reduce the moisture content of the nectar and thus aids sugar concentration. The house bee may load the nectar into the upper section of an empty cell or add it to the honey or nectar of a cell incompletely filled. The speed with which she manipulates the nectar depends on the intensity of the nectar flow. If nectar is abundant, the house bee may deposit her load quickly into a comb cell for later processing.

The time required for the nectar to mature into honey depends for the most part on its original moisture content. For example, if the sugar content is high, as in the nectar of Combretum paniculatum, which is usually over 65%, ripening takes about two hours. On the other hand, if palm wine (which bees enjoy very much) is sent into the hive, more time will be required, since its sugar content is as low as 4.5%. Matured honey usually has over 80% sugar concentration. Ripening time is also determined by the quantity of the nectar: combs completely filled with nectar, even if strongly ventilated, may take as much as 36 days to mature.

Packing water, pollen and propolis

Other essential commodities which are brought in by the foragers and need the attention of the house bee are water, pollen and propolis. Water is required for cooling the hive, especially during the harmattan season, when the atmosphere is very dry and temperatures are too warm for the bees’ comfort. Water is mixed with honey and pollen and then fed to the older larvae, between 3-6 days old. Pollen is also packed to about three-quarters full in comb cells in the brood chamber, sometimes side by side with brood cells. Cells are never completely packed with pollen.

Propolis is a resinous material collected from trees. It is difficult to unload, because it is gummy in consistency, and the house bees have to help the foragers to unload. The carrier holds firmly onto the walls of the hive, and the house bee removes the sticky gum from the hairy corbicula or pollen basket. Sometimes it takes more than three days to off-load a forager. The propolis is either stored or used immediately for the purpose required: to block holes and cracks in the hive, to repair combs, to strengthen the thin edges of the comb, or to make the entrance of the hive watertight or easier to defend. As already mentioned, propolis is also used to cover objectionable material in the hive and to embalm dead intruders such as wax moths, snakes, etc., too large to be removed.

It is interesting to note that house bees are always eager to help unload the field bee that brings in material which the hive requires immediately. For example, when the weather is too warm and water is required to cool the hive, they will pay no attention to foragers bringing in nectar or propolis, who will have to wait until the heat situation is brought under control before they are offloaded.

Executions

Executions are a means of protecting the colony from hunger, disease and any catastrophic event. They may be performed to eliminate strange bees, to kill or drive away old and sick bees, to discourage other hive predators from entering the hive, to remove sick or unwanted unemerged brood, to eliminate useless drones, and to kill unwanted or strange queens.

Guard duty

Guard duty is the final activity of the house bee before she leaves the hive. By this time she has reached peak strength, is very energetic, and is best fit to defend the entrance of the hive, which is also the point of entry of the colony’s enemies.

The guard bee has the duty of inspecting all incoming foragers by smelling their odour. When satisfied, the guard allows the incoming bee to enter unmolested with her load. In most ·cases, foragers with loads to discharge are not intercepted unless the hive is greatly disturbed. After staying at the entrance for a while, the guard may fly out on patrol for some time before returning to the entrance. The guard bee is also responsible for watching any crack through which a robber bee or any other intruder might enter the hive. In an alerted hive, guard bees stand on four legs, their forelegs lifted and they antennae held straight, searching here and there. Any intruder, robber or other enemy first receives a frightening audible warning, followed by a sting; if he persists, the application of the alarm pheromone on the spot where the bee stings quickly summons more defenders. The scent helps other attackers to find the target and follow without delay.

It has been observed that during the brood-rearing season, more guards are stationed at the hive entrance than during the peak of the honey flow.

The field bees

Activities involving flight may start from the third day after emergence from the brood cell, but the young worker begins her actual foraging activity later. Between the 18th and the 21st day, her hypopharyngeal and wax glands have become too weak to function, so that she cannot produce royal jelly to feed the queen and the young larvae, nor wax to build comb cells. But by this time she is in perfect condition to fly and knows the geography of the locality. She therefore starts field work, fetching nectar, pollen, propolis or water, but always concentrating her activity on the immediate needs of the colony.

Observations conducted in several places in Ghana showed that foragers begin to be active as early as 5:15 a.m. and that by 6:30 p.m. almost all have returned to the hive. In the latter part of July, August and September, most foragers brought pollen. By 5:20 a.m. the first consignment of pollen had arrived. More heavy loads of pollen continued to come, and traffic at the entrance was heavy until 7:30 a.m. This phenomenon was repeated between 10:00 and 11:30 a.m., when the sunshine was intense.

Nectar gathering

Nectar, the sweet liquid secreted by plant nectaries, is collected by foragers, taken to the hive and turned over to the house bees for processing. The forager then returns to the flowers and collects more. The number of trips she makes in a day cannot be assessed precisely. It may vary from time to time for a number of reasons: the availability and accessibility of the nectar source, the quantity of nectar present, and the nectar requirement of the colony for the day.

Sight and smell enable the bee to locate sources. She lands on the part of the plant that will support her and dips her stretched proboscis into the corolla of the flower. If there is nectar, she sucks it into her honey stomach. If there is none, she wastes no time before moving to the next flower. Some flowers have more nectar than others. Sometimes the bee can load enough by visiting one, two or three, but in plants with tiny flowers she can only get a full load by visiting hundreds. A fully loaded bee can carry 85% of her own weight.

The time taken to complete a trip varies, but can reach 2 hours. In the savannah, foragers visit certain plants at specific times of the day. The dawadawa plant (Parkia clappertoniana), for example, produces large quantities of nectar and sweet Juice which flows on parts of the stem and branches, but the dry harmattan drains the moisture in the liquid, and the juice becomes so sticky that the bee cannot load it easily. Probably for this reason, bees visit the plant as early as 5:15 a.m. and as late as 6:15 p.m. On each occasion, only one trip is made. By 6:30 p.m., no bees can be found on the tree.

Water collection

Bees consider water-carrying as one of their most important duties. They execute it regardless of what may be involved. If they need Water for the hive, they will resort to drastic methods to acquire it. In water-scarce areas, desperate bees sometimes attack farmers for their sweat, and clothes cannot be washed outdoors in the daytime for fear of molestation by desperate bees searching for water. Thirsty bees visit kitchens, bathrooms, toilets and all obscure humid places. They will land on any moist area, dip their proboscis and suck in water. Loading of water takes only a few seconds. The bee carries it to the hive and returns in a few minutes to reload if water is still present.

The scout bee

Foragers can take on scout duties as well. The scout bee locates food sources and passes on the information to other bees by a series of dance-like movements. She circles around and around, stamping her legs and wagging her abdomen; sometimes she stretches her proboscis, possibly to show the type of food she has found. The onlooking workers watch her dance, interpret it and act accordingly. It is believed that different dances show different types of information to be passed on.

Another most important duty of the scout bee in a new swarm is to search for a suitable accommodation, while the rest of the swarm waits on a tree branch or in a small enclosure. On finding a suitable hollow or hive, she returns to the swarm and performs a characteristic dance to inform them about the find. When two or more bees make different finds, each scout dances especially vigourously in an attempt to win the support of the swarm.

Robber bees

All worker or foraging bees are thieves. They claim anything they like as their own property. They snatch honey away from honey harvesters from other swarms during the daytime, especially when the weather is sunny and bright. In the rich savannah bee-zones where water is scarce, bees easily steal water from villagers. Robber bees visit other colonies’ hives and try to take honey in order to store it in their own hive. The problem of hive robbing is not as serious in tropical Africa as in America and elsewhere. Only very weak colonies are sometimes robbed; usually it is abandoned hives that other colonies invade to take advantage of the honey stored in the comb cells.

It is strange that bees often fail to take advantage of water or any sweet juice located close to the hive, but when it is placed further away (about 20 metres or more) they take it. This shows that the beekeeper should always watch his hives to avoid leakages of honey, for the leak will not be recovered by his own bees but by other bees from elsewhere, thus encouraging robbing.

Source:

http://www.fao.org/docrep/t0104e/T0104E05.htm