The honeybee is a social insect with three type of individuals: the queen, worker and the drone. Each of them has a special function in the colony. The queen is the only female completely developed sexually, that's the reason why it’s the mother of all bees. There is only one per colony, but it's not a "queen" in the sense that she governs the workers or tell any other bee what to do, she simply lays eggs. A very important function of the queen is to ensure the nest stability and continuity. She controls the sex of her offspring: if its a fertilized egg it will be female, if the egg is unfertilized it would be a male.

On the other hand, the worker honey bees do all of the main tasks in the colony maintain it in good condition. They are females that are not fully developed sexually. The tasks change with their age because they're correlated with the physiological development of different glands, but can also change depending on the needs of the colony.

The last type of honey bee are the drones, the males of the colony. They just have one function: fertilize the queen. After mating, the drone dies. They don't have a sting, do not carry pollen, are unable to produce wax and only last six months.¹

Queens lay an egg for each cell. Their yolk serves as food source until, three days later, a larva emerges. On the fourth and fifth day, larvae feed on royal jelly. On the sixth day, larvae transition from jelly to pollen and honey (bee bread), which they will feed on until the ninth day. Brood prepared to be queens are fed royal jelly (and not bee bread) until the ninth day. Larval cells are then capped with wax, where bees will develop as pupae until they emerge depending on their caste. Worker bees emerge on the 16th day, queen bees emerge the 21st and drones emerge last, on the 24th.

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The honeybee's immune system is the principal barrier against diseases and pathogens. It is classified into social and individual immunity ⁴.

The social immunity is a collective behavior seen in Apis mellifera (Honeybee) and other social insects, and it has the objective to reduce the risk of disease outbreaks. Every bee in the colony does small tasks and altogether have a high impact against parasites and pathogens.4 Social immunity is divided into defensive behavior and environment modification. The defensive behavior includes the hygienic behavior as grooming themselves or to each other, exhaustive beehive cleaning of potential infectious elements such as residues or carcasses within the hive. Also, they clean up after the death (2). The environment modification consists of the collection of propolis (plant resins)5 and use them to create an antiviral and antimicrobial envelope for the beehive.⁴.

On the other hand, the individual immunity of honeybees has several lines of innate immune defense against pathogens. The chemical and physical barriers like the exoskeleton cuticle and the peritrophic membranes at the digestive tract are the first line of defense against pathogens. In the case of a breach of the physical and chemical barriers, there is a cellular and humoral response that constitute the second line of defense. The innate immunity of the bee is activated due to the recognition of the structural motifs on the pathogens' surface known as Pathogen-Associated Molecular Patterns by Pattern Recognition Receptors. The signal cascades could active the phagocytosis, coagulation or melanization of the hemolymph or the synthesis of antimicrobial peptides (AMPs) such as abaecin, apidaecin, defensin and hymenoptaecin.⁴.

The antimicrobial peptides are synthesized in the fat body of the honeybee as pro-peptides (inactive-form) and are cleaved (active-form) upon infection. These peptides have properties against bacteria, viruses, and fungi.⁵.

The mouth is the first part of the digestive system. It is in the anteroinferior part of the head and belongs to the licking-sucking classification. The queen, the drone and the worker bee present different structures.⁶

When Bees take liquid foods using the proboscis, which is formed by different pieces of the oral apparatus.⁶ The proboscis is not an organ as such, but it is a group of structures that unite and have a particular function. By this retractable structure is how it ingest and regurgitates, nectar, water or honey.⁷ Bellow is an image where the structure is retracted and when it is not.

When the proboscis is retracted, the tube is under the head; when the bee prepares to absorb liquids, it projects it forward, extending its distal parts around the tongue, in such a way that a tube is formed that closes in front of the distal end of the maxilla; in the back, the labial palps close.⁶

Unfolding the tube is introduced into the liquid, in quick movements back and forth the liquid rises. When the mandible and proboscis are contaminated, are the vehicle for an infestation of larvae by American foulbrood (Paenibacillus larvae) or European foulbrood (Melissococcus plutonius).⁶

The Esophagus is a tube that extends along the thorax, whereby food does it road thanks to its contraction movements, by muscle waves that move in an anteroposterior way.⁶

In the proximal end of the abdomen, the esophagus widens into a sack with thin and highly elastic walls, named the social stomach. When it is filled, their walls expand rhythmically causing their content mix. It is also used as food stock. The proventriculus is a narrow, muscular channel that controls the entry of food into the stomach (ventricle) of the bees, acting as a filter, eliminating the solids from the content of the social stomach. Its previous part is X-shaped. Through this valve, the bee can selectively remove the pollen from the nectar or honey and pass it to the ventricle. Below is an illustration of this valve.^6,7

The ventricle is where the digestion and absorption of food from the food material takes place. The folds of the inner membrane increase the digestive surface. It is a long and wide tube of endodermal origin. In it, there is no cuticular layer, but the peritrophic membrane is present throughout the length of the tube, which is selective and through it pass the digested nouns and mix with the hemolymph. ^6,7,9

In this membrane are collected the liquids coming from the proventriculus, the soluble products of the digestion of the solid foods, the digestive enzymes secreted by the epithelial cells and the fluids reabsorbed by the tubules of Malpighi. The functions of this membrane are:

• Mechanical protection to ventricle cells.
• Physical barrier for digestive enzymes and products of digestion.
• Device to help the process of non-excretion of digestive enzymes.
• Prevention of non-specific ligations of undigested materials with the carrier proteins in the membranes of epithelial cells.

The permeability of this multilaminar membrane is very little known. Today it is known that nutrients must cross this membrane to be absorbed by the epithelial cells to reach different tissues. ⁹

In the larva, it is the place (the ventricle) of attack of Paenibacillus larvae (American foulbrood) the spores of bacteria germinate in the ventricle just after the operculation that is the moment in which the concentration of sugars goes down, later the bacterium invades all the larva. ⁶

The proctodeum is divided into two main parts: the small intestine and the large intestine or rectum, the first is attached to the ventricle by the pylorus, which is the regulating valve of the passage of food between the ventricle and intestines. ⁸

The large intestine contains the rectal organs that serve to absorb water. It is a structure similar to a bag with several longitudinal folds that give it the ability to contract or expand with the presence of intestinal content. The rectum accumulates both digestion residues and the excretions of Malpighi tubes, especially in the winter or rainy seasons. ⁸

The Malpighi tubes are about 100 long sinuous tubes that roll together in the viscera and end at the junction between the ventricle and the small intestine. ⁸