Incredible Body Structure of Honey Bees
The food for honey bees are nectar and pollen from honey plants and polliniferous plants. Bees collect nectar through the proboscis, made up of almost all separated elongated segments. A longish piece of proboscis – tongue – ends with a spoon, fully equipped with longish thick hair. With the spoon bee can lick small droplets of nectar. The droplet rises to the throat by a thin (capillary) tube, located in the middle of the tongue. When the bee takes honey from the cell, it plunges proboscis deeper, and honey rises to the throat by not the capillary, but wider tube, formed by the other components of the proboscis. The bee makes sucking movement by muscles of the pharynx, accelerating feed collecting.
Nectar enters the longish narrow tube – esophagus, which runs from the head to the chest and to the abdomen, where, expanding, it forms honey goiter. Walls of honey goiter are stretched so that it can hold up to 50-60 mg of water. Honey goiter can be compressed by the action of muscles that make up its walls. In the hive-bee passes the brought nectar to bees or puts it in the cell. After honey goiter there is a midgut, which is the main organ that processes and assimilates food. Honey goiter is separated from the midgut with special crotch intestine. Perineum intestine consists of three parts – the head, valves and hoses. The head is inside honey goiter. It consists of four segments, committing continuous sucking movement till honey goiter is filled with fluid. Pollen grains, trapped in goiter with nectar, are captured and through the perineum, intestine fall in the midgut. So the nectar, collected by the bee, is cleared of the pollen grains, which in large quantities are taken with nectar from the anther of flowers. So honey, folded in the cell, is pure and transparent. Sleeve perineum intestine comes inside the midgut.
By this sleeve food can come in small portions into intestine and move further along it. Bowel walls, sometimes wavy cutting, slowly push the food. It leaks from honey goiter into intestine, but it cannot get back into the honey goiter, because, under the pressure the sleeve, clinging to the wall of the gut, closes its own clearance. This ensures a constant purity of honey. Midgut has thick muscular walls, which form large transverse folds. Glandular cells of the intestine secrete digestive juices, which contain enzymes, decomposing not only the sugar and starch but also protein and fat into the most common components. Pollen is digested mainly in the midgut, it is immediately enveloped by mucous gelatinous mass, containing digestive juices. This gelatinous sheath protects the delicate cells of the midgut from damage, also does not allow germs, entered the intestinal tract together with food, to leak to them. Pollen grains have a thick shell, which is not destroyed in the intestinal tract of bees. Digestive juices get inside a pollen grain through the holes (pores) in its shell. By the influence of enzymes the contents of pollen grains – starch, protein, fat – are dissolved and moved into the intestine. Dissolved food is absorbed in the back half of the midgut. Pollen grain shells and other substances stay, but the water, in which is dissolved the food, is decomposed to the most common components, absorbed by the cells of the intestine and its contents are sealed.
Narrow hindgut begins from the end of the midgut. In the place where the midgut becomes hindgut, ducts of so-called Malpighian tubules begin. These vessels – thin tubes in the amount of 100-120 – are the organs of selection, much like the kidneys of animals. The cells of the blood vessels absorb from the surrounding blood the harmful decay products (uric acid, salt, and other substances), which then are poured by the tube into a narrow hindgut and removed. Through the narrow hindgut the undigested remains of food together with the decay products fall into the large hindgut, a tank with folded walls, in which stool is accumulated during the winter. In the spring their quantity can achieve 35-40 mg (almost half the weight of the bee) without any harm to it. In the springtime, during the first flight bees clear intestinal tract.
Inside the walls of the hindgut, there are 6 rectal glands. With their help, the water is absorbed and stool is concentrated. These glands secrete substances that inhibit the growth of rotten microbes. A queen, whom traditionally does not fly out of the hive, lays stool on the cells, the bees clean it immediately. But after unfavorable winter, when the bees eat too much honey or when their function of absorption is impaired in the midgut and hindgut, bees can accumulate excess feces at the end of winter, which pollute the cells and walls of the hive. In such case a lot of bees die.
Bees have two pairs of wings and they are appendages of medium- and metathorax. Wings fully develop only in the transition from the bee pupa to an adult bee. They are laid in a bag-like rudiment of covers of the middle- and metathorax. The pupa grows and this rudiment also does, its ventral and dorsal walls converge. The wing of the adult bee is a thin, elastic plate, with the veins, which are hardened pieces of hollow tubes. During the formation of the wing hemolymph flows there, pulling wing plate. On the wings of bees there are also the following longitudinal veins: subdiscoidal, the first return, the second return. The veins form on the wing closed cells, which, as well as the veins have names: radial, cubital, discoidal. Their names are defined by the adjacent longitudinal veins.
The cubital index helps to determine the breed of a bee, it is defined by a/b*100%, i.e., the ratio of the length of a vein (a) of the third cubital cell to another vein (b). This feature is the same during all the year, is weakly correlated with the other conformation traits. The rear wing has a similar structure, but it is much smaller than the front. In addition, the drones have additional rear wing venation.
specifics of the rear wing venation reflects the individual characteristics of
each queen, and hence the families of bees. Therefore, we can assume that the
specific venation of a rear wing is a morphological sign in the determination
of belonging to a particular group or line of the same breed of bees.
The rear wing is provided at the forefront with a number of hooks, directed upwards. During the movement the front wing with a crease, located on the rear edge, slides on the rear wing and hooks cling to it. This ensures a strong bond between the rear and the front pair. When folded, they are easily separated. Worker bee has on the rear wing from 15 to 27 hooks, the queen – from 13 to 23, a drone – from 13 to 29. In contrast to worker bees, drones can have anomaly – a lot of hooks. There is an increase in the total number of hooks (27-36), the number of abnormal hooks on the wing ranges from 1 to 16. There are also breed differences in the number of hooks. For example, the northern bees have fewer hooks than the south. The junction of the wing to the body is a complex mechanism, which provides a quick sweep of the wing and some turns during the sweep. In addition, the joint provides the folding. The wing is attached to the membrane. Place of the attachment to the membrane is movable.
Veins are mechanical support of a wing; they help to overcome air resistance in flight. There are different longitudinal veins, partially branching, and longitudinal cross-linking to each other. Between the veins the thin transparent membranes are stretched. Pattern of longitudinal and transverse veins is called venation. Every vein, depending on its location on the wing, has a certain name. Four longitudinal veins are as follows:
- Costal vein, forming a thickened leading edge of the wing, goes from the shoulder blade, does not branch.
- Subcostal vein is near the costal, in the middle of the wing merges with it. It also does not branch.
- Medial, or median, vein, short, divided into two branches – the basement, connecting with subcostal, and discoidal.
- Cubital vein starts from the middle vein and stretches along the wing almost to the end.
- Radial vein is associated with cubital and three inter-cubital veins.
- Anal vein runs parallel to the first medial and then diverges from it. Between them, there is a short neural streak.
the role of the support point for the wing. Outside of the column is the long
arm, from the place of attachment of the segment to the membrane to the column
– the short arm. The moving of the back leads to lifting. Swinging of wings is
provided by the fact that the ends of the veins do not reach the edge of the
wing. A significant role in the articulation of the wings plays a series of
plates, some axillary and intermediate. These plates reinforce the base of the
wing, make them bend along outside lines and transfer of motion to the ends of
the veins. Flight of bees is very different from the flight of birds, bee wings do
not have muscles. Moreover, the wings of insects are similar to the wings of
vertebrates, but not homologous. Unlike most birds, insects' muscles are not
attached to the wings, but to the walls of the body in such a way, that even
slight changes in the form of thoracic move wings rapidly up and down.
Muscles play an important role in the movement of the wings during flight as it’s coordinated and directed primarily by muscle energy of indirect action, i.e., muscles that are not connected to the wing. This group includes the dorsal longitudinal and vertical muscles. The reduction of vertical muscle pulls down tergite. As a result, the wings on the opposite side of the pivot point rise. With the reduction of longitudinal muscles the tergite arches, and the wing is lowered. Movement of the body wall is hardly noticeable, but since lever arms on both sides of the fulcrum of the wing have a different length, range of motion in the tips of the wings are hundreds of times more. The second group of muscles – the muscles of direct action, which provide turn of the wing along the longitudinal axis, and take it back and forth.
The main role during the flight is played by the indirect muscles. Chest cavity of a honeybee is entirely filled with them. There are two pair of them. The first pair is attached to the front and back frags of mesothorax. The reduction of these muscles leads to some convergence of frags in the segment by bending up and increase in its curvature. As a result, the base of the wing rises and the wing paddle part falls. The second pair of longitudinal dorsal muscles are considerably smaller than the first. It is stretched between the back frag and scutum. These muscles are also involved in the lowering of the wing. Consequently, the longitudinal muscles play a lowering role. Also the vertical muscles from the back of the chest to chest sternite. In case of their reduction, they drawback to the breast, so that is the rise of the wing paddle part. Sometimes wing flapping frequency is related to the frequency of nerve impulses originating in the muscles involved in flight. But bees flap frequency is independent of the frequency of incoming nerve impulses. When the frequency of nerve impulses exceeds a certain minimum value, wings flap, but with a higher frequency, which is determined by only the muscles, this frequency depends on the tension in the two systems of antagonist muscles.
Direct muscles are pleural muscles of front and back groups and axillary. During the flight a wing turns along the longitudinal axis, and also have a back and forth. The front pair of pleural muscles pulls coastal edge down in case of their reduction, and the front edge of the wing, based on the pleural column, falls down. Rear pair in case of reduction pulls the rear edge of the wing down, is also involved in the folding of a wing. Pleural muscles during flight create a propeller effect. In addition, each wing can be seen as a kind of propeller. The motion of the wing during flight is characterized by a complex trajectory of the form of the number 8, the upper end is tilted back, and during free movement forwards this eight stretches and becomes a sine wave. Complex movements of the wings in flight are a combination of simpler movements up and down, back and forth, changing the slope. In this case, a bee makes a great number of vertical strokes of the wing. There are three types of flight of insects: gliding, parachuting, and rowing. Bees like rowing flight. It is performed with the help of continuous rhythmic beats of its wings.