In this essay we will discuss about honey-bee. After reading this essay you will learn about: 1. Introduction and Economic Importance of Honey-Bee 2. Polymorphism in Honey-Bee 3. External Feature 4. Internal Structures 5. Life-History.
Essay on Introduction and Economic Importance of Honey-Bee:
These insects belong to the order Hymenoptera. The most common species is Apis mellifica. These are well-known for their organised social life and great economic importance. The nest of honey-bee is called bee-hive, which is commonly found on tall trees. It is possible to rear honey-bees in artificial hives and the cultivation of bees for honey and wax is very common throughout the world.
Polymorphism in Honey-Bee:
Within each hive reside thousands of bees of three different forms:
(1) Workers,
(2) Drones, and
(3) Queen (Fig. 110).
1. Worker bee forms the majority within a hive; size is very small; work in number of capacities—cleaner, nurse, builders and architects, technician, soldier and porter.
2. Drone bee—slightly larger than the workers; noisy and idle; comes out of the hive only at the time of nuptial flight.
3. Queen bee—very large with a tapering abdomen; generally a single matured queen is present in each hive; responsible for the laying of eggs.
For the presence of three different morphological forms in one species, these insects are called polymorphic and the phenomenon is called polymorphism.
External Feature of Honey-Bee:
Like a cockroach, the body is divided into three parts:
(a) Head,
(b) Thorax, and
(c) Abdomen.
Each part is provided with various structures which are adapted to the peculiar habit of these insects.
(a) Head:
This region contains:
(1) Three ocelli in the middle,
(2) A pair of much prominent compound eyes,
(3) One pair of long many jointed antennae, and
(4) A number of appendages around mouth, which are specially built for the collection of nectar and building of comb.
Mouth Parts (Fig. 111):
(i) Mandible—one pair; very powerful in worker bees; used during comb building.
(ii) First maxilla—one pair; each consists of an lamina or galea on a basal piece which is made up of stipes and cardo. The maxillary palps are rudimentary.
(iii) Second maxilla—one pair; forms the lower lip; well-formed in workers; lower part united; from the outer side of each maxilla liangs a long labial palp and the inner side is divided into two pans —glossa and paraglossea. The two glossae, one from each second maxilla are fused together to form tongue or ligula.
The paraglossae remain tightly fixed with ligula at its base. The labial palp, ligula and paraglossae, can be set in such a fashion that it forms an airtight tube for sucking nectar. When not in use, the elongated mouth parts are kept folded on the back. This is unlike butterflies, where the funnel remains coiled during un-use.
(b) Thorax:
Thorax is divided into three segments:
(1) Pro- thorax,
(2) Mesothorax, and
(3) Metathorax.
Three pairs of legs and two pairs of wings are the appendages of the thoracic region.
Legs of Honey-Bee:
Legs are built up in the same pattern as that of cockroach, but it has certain modifications which help these insects to their peculiar way of life (Fig. 112).
(i) Legs of Prothorax:
Soft hairs called eye brush are present on the tibia, which help in cleaning pollens and debris from the eye. On the first tarsal segment, number of stiff bristles called pollen brush are present for removing pollens from the body hairs. Tibia holds a spur, and first tarsal segment contains a notch, both of which act as antenna cleaner.
(ii) Legs of Mesothorax:
Pollen brushes are also present on the first tarsal segment. From the tibia hangs a wax spine stick for removing wax from the wax glands.
(iii) Legs of Metathorax:
Inner part of the first tarsal segment contains pollen combs. These combs collect pollens from the pollen brush of other legs. Near the junction of tibia and first tarsal segment, lies another structure called pollen packers which clean the pollen combs. On the outer side of the tibia, there is a basket, called pollen basket, within which pollens are deposited by the pollen packers from the pollen combs.
Wings of Honey-Bee:
The dorsal side of the thorax carries two pairs of wings. Near the base of each wing lies an aperture called stigma. Drones possess the largest wings and queens have relatively smaller wings.
(c) Abdomen:
In workers and queen, the abdomen is divided into six segments but in drones there are seven segments. In drones the abdomen is broad but shorter than the wings, while it is elongated and narrow in the queen.
Abdomen is devoid of any appendage but bears a number of apertures called stigmata on it (5 pairs in queen and workers, and 6 pairs in drones). Only in workers the abdomen contains on its ventral side four pairs of wax- producing glands called wax pockets or wax glands.
The posterior- most tip of the abdomen in queen and workers can be protruded into a sting. With this sting are connected the poison glands. In the queen the sting is also used for the laying of eggs and thus functions as ovipositor.
Internal Structures of Honey-Bee: (Fig. 113):
a. Alimentary System:
Within the body the alimentary canal is divisible into following parts—oesophagus, honey sac, chyle stomach, small intestine, large intestine and anus. The oesophagus is a narrow straight tube passing through the thoracic region. The honey sac is formed by the dilation of the oesophagus within the abdomen. The honey sac leads into the chyle stomach through a passage which is guarded by a complex stopper arrangement.
The chyle stomach is a broad, half-bent tube which opens into the coiled small intestine. The opening is separated by a pylorus. Number of chitinous teeth are arranged longitudinally along the inner wall of the small intestine. Large intestine is dilated and short and is guarded by valves of six plates.
In all the three types, there are three pairs of salivary glands which produce saliva. It mixes with the nectar and pollen grains. The nectar is converted by enzymatic action into honey, which either may be regurgitated into the comb for future use or may be digested. Only the worker bees possess another pair of coiled gland secreting a nitrogenous fluid called ‘Royal jelly’.
b.Respiratory System:
Respiratory system consists of stigmata, trachae, and air-sacs. The stigmata are lateral openings, which may be kept closed externally. The trachae are branched tubes, which ramify all around the body. The air-sacs are large vesicles, which are in connection with trachae.
c. Excretory System:
It is represented by innumerable threadlike Malphigian tubules which open into the small intestine.
d. Circulatory System:
The circulator/system is called as open type of circulation, because there is no definite blood vessels with distinct walls. Blood being pumped by tubular hearts (placed along the mid-dorsal region of thorax and abdomen) passes through the body spaces called hoemocoel. The blood which is known as haemolymph, contains a few amoeboid cells with distinct nucleus.
e. Nervous System:
The nervous system consists of nerve ganglia, ventral nerve cord, and peripheral nerves.
The ganglia are represented by:
(1) Large supra-oesophageal ganglia with broad projection to each compound eye,
(2) Sub-oesophageal ganglia, which is formed by the union of three pairs of ganglia,
(3) Three pairs of ganglia in the thorax, and
(4) Five pairs (in workers) and four pairs (in drones and queen) of abdominal ganglia.
Double ventral nerve cord begins from the sub-oesophageal ganglion and rims posteriorly along the mid-ventral line. The thoracic and abdominal ganglia are placed along the ventral nerve cord. Different peripheral nerves are given out from these ganglia to different parts of the body like, eyes, antennae, mouth parts, legs, wings, etc.
Following sense organs are present in the honey-bee:
(1) Simple eyes—for detecting the intensity of light.
(2) Compound eyes—for vision.
(3) Antennae—for measuring distance and for smell.
f. Reproductive System:
Sexes are separate, the male bees are called Drones and female bee is called Queen. The worker bees are sterile females.
In Drones:
Testis one pair; each testis is connected by a narrow tube called vas deferens. The outer end of it dilates into seminal vesicle, which in turn opens into the ejaculatory duct. The copulatory apparatus is connected with the terminal end of ejaculatory duct. A pair of prominent mucous glands open near its union.
When matured the testes reduce and the spermatozoa crowd near the end of the ejaculatory duct. There the sperms are transferred in packets called spermatophores. It may be noted here that drones develop from unfertilized eggs, therefore they have haploid number of chromosomes. Thus, here during spermatogenesis, no meiosis occurs.
In Queen:
Large and prominent paired ovaries. Each with numerous tubes containing eggs at different stages of maturity. Each ovary opens into an oviduct. The two oviducts unite to constitute a common oviduct, which opens through a copulatory pouch. The inner end of the oviduct is connected with a round vesicle called spermatheca.
Process of Reproduction:
When matured the queen takes a nuptial flight with a number of drones. The drone which is able to copulate the queen, looses its copulatory apparatus and dies. The sperm cells remain stored in the spermatheca of the queen.
At the end of nuptial flight when the queen returns to the hive it starts laying eggs. The fertilization occurs only at this stage and is believed to be either under the ‘voluntary’ control of the queen or depends upon the size of the cell where the egg is laid.
Life-History of Honey-Bee:
The queen lays fertilized as well as some unfertilized eggs. The fertilized eggs develop either into queen of worker but unfertilized eggs develop parthenogenetically into drones. Within three days of laying, the eggs develop into larvae. These larvae are fed differentially.
The larvae which will become drones are fed with a mixture of honey and pollen grains, called bee-bread. The worker larvae are fed only with honey. The larvae which are i destined to be queen are fed with a special food called ‘Royal jelly’.
This jelly is prepared within special glands of the workers, which open into their pharynx. It is said that workers decide the number of queens to be developed. Accordingly, the workers remove certain larvae before the third day of development in a special large chamber called queen’s chamber.
The feeding of larvae continues for five days, which results into tremendous growth. Then the larvae spins a cocoon around its body and enters into a pupa stage. Rapid transformation of body takes place within the cocoons and ultimately the adult bee cuts its way out of the cell.
The worker bee takes twenty-one days to develop, drones require twenty-four days and the queen leaves the cocoon on the fifteenth day. If several queens are produced, only one survives while others are eliminated.
Swarming of Bees:
With the emergence of new queen, the old queen vacates the hive. She, being accompanied by a large number of workers fly to a suitable place for building a new hive. This phenomenon is called swarming.
Duties of Worker Bees:
The painstaking observations of Rosch and others have revealed the changing duties of worker bees. The workers start working immediately after coming out of the pupal case, which may be described as below.
1st-3rd day—clean the cell for reuse.
4th-9th day—act as nurses, feeds the larvae with their own secretion or honey produced by others.
10th-16th day—Act as builder and architects from the wax produced by their own wax glands they make new cells in comb.
17th-19th day—receive nectars from the bees which are acting as porters and convert it into honey. By the fanning of wings they can also either cool or warm up the hive. Remove all debris from the comb.
21st-25th day-—work as a soldier to protect the hive from foreign intruders including bees from other hives.
25th day onwards—work as foragers. Begin to collect nectar and pollen from flowers. In the European countries, it is detected that life span of a worker bee as adult lasts only for six weeks.
Language of Honey Bee:
It has now been unequivocally demonstrated that honey-bees are capable of passing information, regarding the location of food; by a peculiar dancing they not only indicate the direction but also give an approximate measurement of the distance. For their intricate and well-co-ordinated activities, the honeybees have been long well-known to the students of animal behaviour.