Worker bee

Worker bees (with queen)

A worker bee is any female (eusocial) bee that lacks the full reproductive capacity of the colony's queen bee; under most circumstances, this is correlated to an increase in certain non-reproductive activities relative to a queen, as well. Worker bees occur in many bee species other than honey bees, but this is by far the most familiar colloquial use of the term.

Workers gather pollen into the pollen baskets on their back legs, to carry back to the hive where it is used as food for the developing brood. Pollen carried on their bodies may be carried to another flower where a small portion can rub off onto the pistil, resulting in cross pollination. Almost all of civilization's food supply (maize is a noteworthy exception) depends greatly on crop pollination by honey bees, whether directly eaten or used as forage crops for animals that produce milk and meat. Nectar is sucked up through the proboscis, mixed with enzymes in the stomach, and carried back to the hive, where it is stored in wax cells and evaporated into honey.

Life cycle

Honey bee workers keep the hive temperature uniform in the critical brood area (where new bees are raised). This is in the centre frames of the brood box. Workers must maintain the hive's brood chamber at 34.4 °C to incubate the eggs. If it is too hot, they collect water and deposit it around the hive, then fan air through with their wings causing cooling by evaporation. If it is too cold, they cluster together to generate body heat. This is an example of homeostasis.

The life of all honey bees starts as an egg, which is laid by the queen in the bottom of a wax cell in the brood area of a hive. A worker egg hatches after three days into a larva. Nurse bees feed it royal jelly at first, then pollen and honey for six days. It then becomes an inactive pupa.

During its 14 days as a pupa, sealed in a capped cell, it grows into a worker (female) bee, emerging on the 21st day. In most species of honey bees, workers do everything but lay eggs and mate, though Cape honey bee workers can lay eggs. They build the comb from wax extruded from glands under their abdomen. When fully developed, they perform a number of tasks (see below).

Swarming behavior

When a colony absconds (all bees leave the colony) or divides and so creates a swarm and then establishes a new colony, the bees must regress in their behaviour in order to establish the first generation in the new home. The most urgent task will be the creation of new beeswax for comb. Beekeepers take advantage of this by introducing swarms into new or existing colonies where they will draw comb. Comb is much more difficult to come by than honey and requires about six times the energy to create. A newly hived swarm on bars (top bar hive) or empty foundation (Langstroth box hive) will often be fed sugar water, which they can then rapidly consume to create wax for new comb. (Mature hives cannot be so fed as they will store it in place of nectar, although a wintering hive may have to be fed if insufficient honey was left by the beekeeper.)

Progression of tasks

Cell cleaning (days 1–2)

Brood cells must be cleaned before the next use. Cells will be inspected by the queen and if unsatisfactory it will not be used. Worker bees in the cleaning phase will perform this cleaning. If the cells are not clean, the worker bee must do it again and again.

Nurse bee (days 3–11)

Nurse bees feed the worker larvae worker jelly which is secreted from glands that produce royal jelly. They will also go into the special cells to create a semi-royal jelly that is similar to the royal but it tastes more like honey.

• Advanced Nurse Bees (days 6–11)
  • Nurse Bees will then feed royal jelly to the queen larva and drones receive worker jelly for 1 to 3 days at which time they are started on a diet of honey

Wax production (days 12–17)

Wax bees build cells from wax, repair old cells, and store nectar and pollen brought in by other workers. Early in the worker's career she will exude wax from the space between several of her abdominal segments. Four sets of wax glands, situated inside the last four ventral segments of the abdomen, produce wax for comb construction.

Worker activities

Honey sealing

Mature honey, sufficiently dried, is sealed tightly with wax to prevent absorption of moisture from the air by workers deputized to do this.

Drone feeding

Drones do not feed themselves when they are young; they are fed by workers and then when the drone bees get older they feed themselves from the honey supply.

Queen Attendants (days 7-12)

Queen attendants take care of the queen by feeding and grooming her. Yet, even more important is their incidental role in spreading Queen Mandibular Pheromone (QMP) throughout the hive. This is a pheromone given off by queen. After coming into contact with the queen, the attendants spread QMP throughout the hive, which is a signal to the rest of the bees that the hive still has a viable queen.

Honeycomb building

Workers will take wax from wax producing workers and build the comb with it.

Pollen packing

Pollen brought into the hive for feeding the brood is also stored. It must be packed firmly into comb cells and mixed with a small amount of honey so that it will not spoil. Unlike honey, which does not support bacterial life, stored pollen will become rancid without proper care. It has to be kept in honey cells.

Propolizing

The walls of the hive are covered with a thin coating of propolis, a resinous substance obtained from plants. In combination with enzymes added by the worker this has antibacterial and antifungal properties. Propolis is used to aid with ventilation and at the entrances of hives.

Some bees add excess mud to the mixture, making it geopropolis, such as in the bee Melipona scutellaris.^[1] Geopropolis displays antimicrobial and antiproliferative activity and has been proven to be a source of antibiofilm agents. It also presents selectivity against human cancer cell lines at low concentrations compared to normal cells.^[2]

Mortuary bees

Dead bees and failed larvae must be removed from the hive to prevent disease and allow cells to be reused. They will be carried some distance from the hive by mortuary bees.

Fanning bees

Worker bees fan the hive, cooling it with evaporated water brought by water carriers. They direct airflow into the hive or out of the hive depending on need.

Water carriers

When the hive is in danger of overheating, these bees will obtain water, usually from within a short distance from the hive and bring it back to spread on the backs of fanning bees. The worker bee has a crop separate from the nectar crop for this purpose.

Guard bees

Guard bees will stand at the front of the hive entrance, defending it from any invaders such as wasps. The number of guards varies from season to season and from species to species. Entrance size and daily traffic also play an integral role in the number of guard bees present. Guard bees of the species Tetragonisca angustula and Schwarziana quadripunctata are examples of eusocial bees that have been observed hovering at their nest entrances, providing more protection against intruders.^[3][4]

Foraging bees (days 22–42)

The forager and scout bees travel up to 3 kilometres (1.9 mi) to a nectar source, pollen source or to collect propolis.

Genetic characteristics

In most common bee species, worker bees are infertile due to enforced altruistic kin selection,^[5] and thus never reproduce. Workers are nevertheless considered female for anatomical and genetic reasons. Genetically, a worker bee does not differ from a queen bee and can even become a laying worker bee, but in most species will produce only male (drone) offspring. Whether a larva becomes a worker or a queen depends on the kind of food it is given after the first three days of its larval form.

Stinger

The stinger of a black honeybee torn off its body and attached to a protecting dress

The worker bee's stinger is a complex organ that allows a bee to defend itself and the hive from most mammals. Attacking bees aim for the face by sensing regions with high levels of carbon dioxide (like mosquitos). Bee stings against mammals and birds typically leave the stinger embedded in the victim due to the structure of flesh and the stinger's barbs. In this case, the venom bulb stays with the stinger and continues to pump. Upon losing its stinger, the bee will subsequently die since the portion where the stinger bulb was removed rips out part of its insides.

The barbs on the stinger will not catch on most animals besides mammals and birds, which means that such animals can be stung many times by the same bee.

Stingless bees

There are many bees in this group, native to all continents except for Europe and Antarctica, that have workers which do not have stingers. These bees are not defenseless, however, as they can bite with their mandibles, occasionally releasing caustic secretions at the same time, similar to the defenses of some ants.

References

• The Honey Files: A Bee’s Life, A Teaching Guide, National Honey Board, 2001 
• Organization of a bee colony, FAO 

External links

• Worker Bees

See also