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Bees. What they are, how they live and what they do

Bee society

The first and perhaps most specific characteristic of bees is how they lives as a community. A bee cannot live alone: by nature it can only survive thanks to the group of which it is a part, the bee “family” or “colony”, which is why we speak of the hive as a super-organism.

The queen bee is the only fertile female in the hive, and the only one able to reproduce. Its task in the hive is to produce the members of the colony, so as to give it the necessary continuity. During her period of activity, she lays several hundred eggs every day, from which are born mainly sterile female bees, the worker bees.

The worker bees make up the vast majority of the colony and carry out all the tasks necessary for its daily survival. Their behaviours determine the major changes in the life of the colony. Each worker bee lives from a few weeks to several months, depending on the season, and the perpetuation of the colony is ensured by their continuous replacement.

The third member of the bee family is the male, the drone, whose sole task is to reproduce. He does not contribute in any other way to sustaining the family and, for this reason, his presence in the hive is limited to the periods in which the family multiplies through swarming (spring and summer).

 

What do bees do in the hive?

One of the main tasks of worker bees is to procure food for the entire colony. Bee foods, nectar, pollen and honeydew, are produced by plants and worker bees scour the territory far and wide to find them, collect them and store them in the hive for times of need. Once back in the hive, the forager bees transfer their load to those that populate the hive (the “house bees”). These dry the nectar and thereby transform it into honey through mechanisms in which the crop is simply exposed to the warm, dry air of the hive; an initial drying stage is performed by the house bees, who pass the honey droplets between them mouth-to mouth several times; in a second step, the almost-ready honey is transferred to the cells of the honeycombs, which are only partially filled and left open for the evaporation process to complete.

When the nectar has turned into honey, that is, when it has lost enough moisture to no longer be vulnerable to normal degrading microorganisms, the bees seal the cells with a layer of wax (operculum) which they secrete to prevent moisture exchanges and ensure the preservation of the product (“mature” honey). An important factor in all of this is that the colony is able to regulate the temperature and humidity of the hive. This is also done by the worker bees, who produce heat through muscle contraction when necessary, and ventilate with their wings when air exchange and cooling is needed, even collecting water from outside and pouring it on the honeycombs when a more drastic temperature reduction is required.

A specific trait of hive life is food sharing: nutrients brought into the hive are passed mouth-to-mouth from one bee to another, so that resources, whether few or many, are evenly divided. This mechanism, known specifically as trophallaxis, ensures that each member of the colony is in harmony with the others and standardises the behaviour of all individuals.

 

The “technical language” of bees

All the events that occur in the colony are elicited through the circulation of pheromones, chemical substances secreted by the bees which function as information distributors, thus allowing bees to carry out, coordinate and regulate various activities in space and time without causing confusion.

Bees also have another system to communicate with each other, which is normally called a “bee dance”. When a foraging bee needs to communicate to the discovery of a new food source to others, and to indicate the direction, distance and type of harvest, it does so through a dance. It is a unique example of symbolic language in the animal world. The orientation of the dance on the honeycomb communicates to the other bees the direction they must take as they leave the hive, in relation to the position of the sun, to find the food. The speed of the dance is proportional to the distance to be travelled and the type of resource is communicated with a small taste of what has been found.

 

Bees are born, grow and die, but the hive is eternal

The life of the hive is ensured by the continuous exchange of worker bees. The queen bee lays one egg for each cell; the egg is cared for by the worker bees and the larva that is born three days later is fed with a mixture of honey, pollen and royal jelly, a glandular secretion which for bees is analogous to milk in mammals.

Young adult worker bees feed their younger siblings, keeping them warm with their bodies, cooling them with ventilation if necessary and feeding them as needed. After a few days, the larvae, now grown, are ready to transform into adult bees, through the complex process of metamorphosis. At this stage the larvae, which are transforming into pupae and then into adults, stop feeding and

are left undisturbed under a layer of wax, with which the cells are sealed during this delicate period. Once they become adults, worker bees can live from a few weeks to a few months, depending on the season. A hive is composed of several thousand individuals, fewer during the winter and up to 50,000 in the active season.

 

Swarming, or the reproduction of the hive super-organism

The life of the hive requires the queen bee to lay eggs, from which worker bees are born, allowing it to remain populated and survive from one year to the next, despite the short life span of the worker bees. The queen bee may live a few years, but what ensures the continuity of the hive when the old queen dies? In this case, some of the “normal” worker eggs are cared for in a special way by the nurse bees, who modify the shape of the cells and overfeed the larvae with royal jelly.

These special larvae develop into queen bees. Young queen bees are raised not only when the old queen dies, but also every spring, when resources are more abundant and the hive is more populated. This triggers a mechanism that allows the hives to multiply and the species to perpetuate itself. New queen bees are nurtured in this period and when they are about to leave the royal cells, the old queen and some of the worker bees leave the hive to search for a new home. The departing group is referred to as a “swarm”.

The house is inherited by the remaining hive: the first of the remaining queens to be born disposes of all her rivals before they emerge from the royal cells. She must then go out to perform her mating flight, mating with several drones to acquire a supply of male sperm sufficient for several years. Once back in the hive, she starts to lay eggs and will do nothing else for the rest of her life.

 

The bee house

In nature, bees seek shelter in natural cavities such as hollow trees and rock crevices, but nowadays it is easier to find a natural swarm in artifacts such as chimneys, roller shutter boxes and cavities in buildings. In modern-day beekeeping, beekeepers provide their bees with adequate housing: hives. Within these natural or artificial shelters, bees build their honeycombs from wax, each consisting of thousands of hexagonal-shaped cells. The cells serve as cradles for the young bees and shelves for supplies. The honeycombs are formed by the worker bees with wax, a substance they produce by secretion; in this they differ from the nests of wasps and hornets, which are built with cellulose paste that those insects obtain from plants.

 

The search for food

Many types of insects feed on flowers, some gnaw them completely, but many appropriate food substances produced by the flower itself without damaging it, indeed performing an invaluable service for the plant. Several flowers provide insects with a sugary liquid (nectar) that they use as food. By visiting the flowers, they become unconscious carriers of pollen, the equivalent of the male reproductive element, and thus allow the pollination of plants that are far from one other (cross pollination). The reproduction of many plants is therefore only possible thanks to the action of pollinating insects.

Nectar is a sugary liquid produced by flowers; for bees it is their daily bread, a source of carbohydrates and therefore of energy. Transformed into honey, through a process to evaporate the excess water, it becomes their winter food supply. To transport the nectar, the bee stores it in its body, sipping it down and keeping it in a special pouch in the oesophagus, the honey stomach.

Pollen is the structure used in higher plants to transport the male gametes and it therefore has an essentially reproductive function. However, it is rich in essential food substances (proteins and vitamins) and is a valuable food for many insects.

Flowers generally produce it in far more abundant quantities than are strictly necessary for fertilisation and it can be clearly seen at the end of the stamens in the form of a vividly coloured, thick powder. The bees collect it thanks to a “brush and comb” system: the pollen grains remain stuck in the thick hairs that cover the bee’s body. The bee brushes its body with its forelegs and thus collects the pollen, which it then kneads with a drop of nectar and stores it in special sacs, called pollen baskets, on its hind legs.

In nature, bees have another source of sugary food: honeydew. The sugar secretions of various insects that feed on the sap of plants are called “honeydew”. To obtain the necessary amounts of essential substances they need to live and multiply, these insects (aphids, buzzards, cochineals) are forced to consume huge amounts of sap. After retaining the most valuable contents, they externally secrete the waste products, which are still rich in nutrients, particularly sugars. Such waste is not tolerated in nature! Bees and ants remedy this by recycling these secretions. Bees use honeydew as nectar, to feed themselves and to make honey from it, honeydew honey, which is characterised by its dark colour and particular nutritional richness compared to nectar honeys.

 

Lethal weapon

A store of food such as that found in a hive is rare in the wild and is highly appealing to many predators. This is why bees are equipped with a very effective defence weapon, without which they could not defend the fruit of their labours, which is essential for the survival of the colony during the winter months. All worker bees are equipped with this defence system, a stinger, with which they inject a powerful venom into their enemies. However, they only use it when strictly necessary, as it is a double-edged sword. Once a bee stings, it then dies, so it is clearly not so convenient for bees to use this weapon. A bee engaged in its daily occupations away from the hive has no aggressive instinct and no desire to sting, while the opposite is true for the bees stationed at the door of the house to patrol the surroundings.

Bees and the environment

Bees and other pollinators play a fundamental role for the environment. In fact, it is thanks to them taking pollen from one flower to another on their bodies that many flowering plants can reproduce.

In the modern world, the role of bees is even more important, since in many areas the density of wild pollinators has been greatly reduced and numerous cultivated plants need pollinators to produce (fruits and seeds) and reproduce. So the most valuable product of beekeeping is not honey, but what agricultural crops are able to produce thanks to pollination by bees.

Beekeeping also has a positive effect on the environment, contributing to the reproduction of plant species and promoting their conservation. Beekeeping is perhaps the productive activity with the least negative impact on the environment, as its exercise does not damage the local area and bees use resources (nectar, honeydew and pollen) whose removal leaves plants enriched and more vital. It is dramatically evident, however, that bees suffer due to many human activities. We spread highly toxic substances such as agricultural insecticides in the environment, we destroy their food sources with herbicides, we modify their most favourable environments in a thousand different ways, both directly, with fires, uncontrolled development, the spread of industrial crops and over-exploitation of soils, and indirectly through climate change, drought and desertification caused by the accumulation of carbon dioxide in the atmosphere.

The widespread bee mortality, which began to be widely talked about in the mid-2000s, makes it clear that the environment in which bees are forced to live and seek their food is no longer suitable for their needs.

If the world, as we have degraded it, is no longer suitable for the life of bees, we may ask ourselves if it is still suitable for human life…

 

Fonti:

informamiele.it

unibo.it

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