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Basic honey bee biology

 

most familiar are the worker bees. These are relatively short-lived (4-5 weeks), but are familiar to us since it is their job to forage outside the hive for nectar, pollen and water. Workers perform different tasks according to their age. Young bees are not completely formed when they emerge. The hypo-pharyngeal, wax and venom glands are not fully functional and thus the only job that they can do is to clean the used cells. A few days later the hypo-pharyngeal glands mature and they begin to feed larvae. When a bee has developed competent venom glands it will be enrolled as a guard bee. Worker bees become foragers once they begin to secret the enzymes that transform the nectar to honey. Other jobs include grooming, keeping the nucleus of the colony warm or ventilated, using the wings, to cool the nucleus and avoid overheating. Even though the jobs are age related, bees can swap occupation if the colony needs more “personnel” in a particular job (Bailey, 1981).


Life cycle

The honey bee passes through four stages during its life cycle:  egg,  larva,  pupa and finally adult.

Eggs are laid and develop in cells of the wax honeycomb, itself a product of the worker bees. During the first days of the larva stage, nurse bees feed the larvae with a controlled amount of royal jelly and later with beebread and honey.

During the transformation from larva to pupa, the adult bees seal the cell with a layer of wax. This helps to maintain the environmental conditions inside the cell constant and assists in the metamorphosis of the pupa into the adult bee.


The nest

A nest cannot be considered an isolated environment. In fact bees can fly for about 5 km around their nest looking for nectar, pollen or water and during these “travels” they can came into contact with bees that do not belong to their colony. It happens quite frequently that bees do not return to their original nest, but may enter another, a phenomenon termed drifting (Huang and Robinson, 1996; Morse, 1997; Fries and Camazine, 2001;Cordoni and Spagnuolo, 2007). Other means for exchange between colonies include robbing the stores of a weaker colony or mature drones drifting prior to mating. On this occasion many drones from different colonies can mate the same queen (Morse, 1997). All of these routes promote mixing of bee populations and provide a means for the spread of infection from one colony to another (Fries and Camazine, 2001). Finally another route is offered by beekeeping practices, if conducted by inexpert beekeepers these will also allow the spread of diseases between the colonies.

Amongst the Hymenoptera, two species are of economic interest to man, the European honey bee (Apis mellifera) and the Eastern honey bee (Apis cerana).

Bees are social insects and in summer a colony is composed of about 50,000 bees, a single queen, and a few hundred drones. The three casts are morphologically distinct (Figure 1) The queen is long lived (2-5 years) and her major role is to lay eggs. However, she is also the fulcrum of the colony and coordinates all of the jobs that have to be carried out in the hive (nest). This is achieved by secretion of different pheromones in different amounts establishing positive and negative feedback with the needs of the hive and with the work done by the other honey bees. For example if in the hive there is honey shortage, the queen may receive less food thereby starting an appropriate chemical production which may cause the forager bees to collect more nectar. With more the queen is angry with more the pheromone will be produced in larger quantity modulating in this way the number of honey bees that need to go out of the hive and search for the nectar. The queen triggers colony reproduction by a process called swarming. In this mechanism, the queen leaves the colony in early summer taking more than half of the workers with her. During the first couple of days they wait in the proximity of the original colony, then they fly away looking for a good site to found a new colony. The colony the queen has left behind is temporarily queen-less, triggering the remaining worker bees to supplement the standard brood food of some fertilised eggs left behind by the previous queen with royal jelly. These eggs are then raised as emergency queen cells and the first virgin queen to emerge will likely kill all other developing queens to become the reigning queen.

When the queen is lost through swarming queen cells are already present, but, if the colony might loose the queen for any reason, any larva can became a queen if fed with royal jelly.

The function of the drones is only to mate the queen and they die after they have accomplished their job. Unmated drones are ejected from the colony by worker bees in late autumn (Morse, 1997).

The bees with which we are

Fig 1: External morphology of bees belonging to each cast. The Queen and the drones are distinguishable from the worker bees because of their bigger dimensions. The shape of the abdomen, pointed or round shaped, is the main characteristic by notice to distinguish the queen from the drones (MAAREC 2008).