Africanized bees are useful, but defend themselves

There are bees that do not sting, such as those from the Meliponini tribe. And there are those that sting, like the Africanized bee or bumblebees. The stings can be very painful and can sometimes cause serious problems, depending on the person's sensitivity, whether they are allergic to bee toxin, the number of stings and the volume of toxin injected.

It is often said that bees are aggressive, but in reality, they are defensive. Africanized bees defend themselves by stinging the aggressor when they feel that someone is threatening their survival or the integrity of their colonies.

In humans, when an attack occurs on the body, with the presence of an exogenous substance, the immune system is activated, as a form of protection, to avoid damage and even save life. The body's reaction to the bite varies from minor inflammation with erythema, redness and itching at the site of the bite, to very serious symptoms such as respiratory arrest and heart problems.

In the most serious cases, the main symptoms are a generalized feeling of malaise, tingling, dizziness, itching and hives. Swelling of the lips and tongue occurs, followed by obstruction of the airways, with difficulty breathing, tachycardia, drop in pressure and intense sweating. Other symptoms include dyspnea, wheezing, stridor, dysarthria, dysphonia, asthenia, confusion, sensation of imminent death, cyanosis, sphincter incontinence, which can lead to loss of consciousness, anaphylaxis and organic collapse.

Poison and reaction

Bees inject between 50-100 µg of venom per sting, reaching up to 300 µg, which is the maximum content of the venom sac. Bee venom is made up of peptides, a complex mixture of biogenic amines and high molecular weight proteins, mostly enzymes. Melittin is the main component of bee venom, accounting for up to 50% of the weight of dry venom. It is made up of 26 amino acids and can cause the destruction of red blood cells, leukocytes and hepatocytes. The most important allergen is phospholipase A2, a glycoprotein composed of 134 amino acids, whose activity is related to membrane degradation. Another allergen is hyaluronidase, which hydrolyzes hyaluronic acid and facilitates the diffusion of the poison through the connective tissue.

The immune system reacts to any foreign substance injected into the body, which may come from saliva, poison, anticoagulants or toxins. It may seem contradictory that the body's defense system is responsible for a reaction that can cause such serious problems. However, the immunological response is a characteristic with differences between organisms, and the intensity of the reaction can vary from mild to very intense. When bee toxin is injected into an organism, mast cells – which are cells that make up the immune system – produce antibodies to neutralize the toxin. When antibodies come into contact with the toxin, chemical reactions occur, with the concomitant release of histamine by mast cells. Histamine is responsible for increasing blood circulation, which explains the first symptoms, such as redness, edema and itching.

So far everything is going well. The problem occurs in supersensitive organisms, which triggers the severe symptoms described above which, in extreme cases, can lead to the bitten individual's death. According to statistics, about 70 people die each year in the USA as a result of bee stings. In Brazil, according to SINITOX from the Ministry of Health, accidents with venomous animals - which includes bees - represent the second cause of toxicological accidents, just below medicines, but there is no specific reference on the number of poisonings caused by bees.

Care

The first precaution is to always stay away from places where there are bees, avoiding messing with them or taking any action that could be interpreted as a threat to an isolated bee or a colony.

When observing the attack, if the stinger is still stuck to the skin, it is important to remove it immediately to stop the instillation of toxins. When the first symptoms appear that go beyond pain or local swelling and, especially, if the person stung is allergic or has a history of reactions to bee stings, they must be urgently taken to a hospital, where they will receive appropriate treatment.

The removal of bee colonies located in public places or residences must be carried out by professionals duly trained and protected with specific PPE for dealing with bees.

The main recommendations for avoiding accidents with bees include:

• Keep distance from Africanized bee colonies;

• If approaching is necessary, the person must be protected with appropriate clothing and equipment (overalls, gloves, mask, boots, fumigator, etc.);

• Do not circulate and, especially, do not make sudden movements in the bees' flight path;

• In proximity to bees, avoid irritating noises (tractors, harvesters, noisy engines), use perfumes or deodorants, have the odor of human sweat and wear dark colors (especially black and navy blue), as these actions are associated with bee attacks .

Bees are very useful, both for their products – honey, wax, propolis – and for the ecosystem service of pollination, which benefits crops and wildlife. But, like all living beings, they have mechanisms to protect their own lives and those of their community, which is why basic rules must be respected to avoid accidents involving them.

By Décio Luiz Gazzoni, Agricultural Engineer, researcher at Embrapa Soja, member of the Sustainable Agro Council and the Scientific Council of A.B.E.L.H.A.