The secret of bee venom called apitoxin. They use it as a defense system, because bees do not attack, they defend themselves against predators.
The apitoxin is the poison secreted by Apis mellifera worker bees of various bee species, which use it as a means of defense against predators and for bee-to-bee combat. In venomous species, the ovipositor of the workers has been modified to become a bearded stinger. It is widely used as a complementary treatment in Apitherapy with very good results.
Apis mellifera bee defense mechanisms
When injected, they induce the recipient to perceive greater pain or damage than has actually been inflicted. This causes the death of the worker by detachment of its intestines.
They use it to defend themselves against predators, to defend themselves from pillage or if they feel threatened.
What is Apitoxin?
The venom of Apis mellifera is a colorless and bitter liquid; its active composition contains a mixture of proteins, which are intended to cause local inflammation in the attacking organism, and also acts as an anticoagulant.
A bee can inject 0.1 mg of venom through its stinger. Apis.m. poison. has similarities with that of the sea nettle toxin.
Contains Formic Acid
The effects are usually attributed to the acidity of the compound, in reality formic acid is hardly present, and only comes from one of the two glands involved in the secretion of the venom. One of these secretions is acidic.
However, the most active of these appears as a strongly alkaline liquid consisting of a mixture of proteins, mainly the cytotoxin polypeptide Melittin (chemical formula: C131H229N39O31).
All the substances in bee venom are known as Apitoxin. Secreted by the workers of several bee species, which use it as a means of defense against predators and for bee-to-bee combat.
The fundamental effect of the venom is cytotoxic, destroying cell membranes and inducing pain receptors to perceive greater damage than has actually been inflicted. The sinus glands, in turn, produce an acid toxin.
Apitherapy with apitoxin, bee venom
Apitoxin is sometimes used medicinally in the so-called apitherapy, it should always be practiced by a physician or a qualified apitherapist.
It is used as a complementary or alternative treatment for the symptomatic relief of rheumatism and other joint conditions, due to the alleged anti-inflammatory properties of peptide 401, apamin.

It is an effective pain suppressor, and melittin, which acts on the immune system by correcting antibody attacks on the joints.
Chemically, bee venom is quite complex. It contains a large number of compounds. Some of them are volatile and constitute the alarm pheromone, others, heavier, concern the poisonous function of the liquid:

Apitoxin venom compounds of Apis mellifera
Water (88%)
Enzymes, among them phospholipase A and hyaluronidase
Active compounds, percentages of dry weight, without water:
Amino acids, phospholipids and glucides 20% Amino acids, phospholipids and glucides 20% Acids, phospholipids and glucides
Amines, including histamine
The main component is melittin, a compound that accounts for 52% of the peptide venom.
Apamina increases the production of cortisol in the adrenal gland. Apamin is a mild neurotoxin.
Adolapin, which constitutes 2-5% of the peptides, acts as an anti-inflammatory and analgesic, as it blocks cyclooxygenase.
Other bee venom compounds
Phospholipase A2 amounts to 10-12% of the peptides and is the most destructive component of apitoxin. It is a phospholipase that degrades cell membranes. It also causes a decrease in blood pressure and inhibits blood clotting.
Phospholipase A2 activates arachidonic acid, which is metabolized by cyclooxygenase -cyclo to form prostaglandins-, prostaglandins regulate the body’s inflammatory response.
Hyaluronidase contributing 1-3% to peptides, dilates capillaries causing the spread of inflammation.
Histamine contributes 0.5-2% and is involved in the allergic response.
Dopamine and noradrenaline which contribute to the increase in pulse rate 1-2%.
Protease inhibitors at 2% and act as anti-inflammatory agents and stop bleeding.
Tertiapin, composed of 21 amino acids, is a potent potassium channel blocker, related to the reduction of neuronal and cellular electrical conductivity.
On rare occasions, hypersensitive individuals may suffer anaphylactic shock from a sting, but under normal conditions it will take many stings in a short period of time to cause problems due to direct toxicity.
Source:http://www.scielo.org.co/pdf/iat/v16n3/v16n3a3.pdf
Castillo Arias, Marianela. Profesora de apicultura y gestora de comunidades – Socia de Ecocolmena