Discovering the Secrets of Honeybee Anatomy and Physiology: A Comprehensive Guide for Beekeepers

The honeybee abdomen houses sections of the digestive system that play roles in the digestion and absorption of nutrients.

The honey stomach, found in worker bees, acts as a temporary reservoir for storing nectar. Bees collect nectar and water in their honey stomachs and bring it back to the hive, where it is transferred to processing bees to be converted into honey.

The proventriculus and ventriculus are where the main processes of digestion and nutrient absorption occur. The hindgut is responsible for waste elimination, and bees use Malpighian tubules, which are equivalent to kidneys in vertebrates, to excrete waste from hemolymph (insect blood).

The fat body, consisting of a layer of white or cream-colored cells, plays multiple roles in the honeybee's body. This tissue, besides storing fats, glycogen, and proteins, also participates in the production of an important protein called vitellogenin.

Vitellogenin is a storage protein that plays a key role in the social behaviors of bees, particularly in nurse bees and queens. Additionally, the fat body is involved in detoxifying harmful compounds and maintaining the bee's immune system (Fahrbach, 2006).

The honeybee's circulatory system is open, meaning that blood or hemolymph does not flow in closed vessels. The bee's heart is an open tube located in the dorsal part of the body, directing hemolymph from back to front. Unlike vertebrate blood, hemolymph does not carry oxygen; instead, gas exchange occurs through the respiratory system. This simple structure pumps blood to different parts of the body using a muscular system and one-way valves (Simpson, 1960; Winston, 1991).

The reproductive system in honeybees fundamentally differs among queens, workers, and drones:

• Queen: The queen honeybee, due to her primary reproductive role in the hive, has a highly advanced reproductive system. The queen possesses two large ovaries in her abdomen, each containing 150 to 180 ovarioles. This structure allows the queen to lay over a thousand eggs daily. One of the unique features of the queen's reproductive system is the spermatheca, which can store millions of sperm from drones during mating flights. These sperm are used for fertilization throughout the queen's lifetime (Koeniger et al., 2014). The spermatheca enables the queen to produce fertilized eggs that develop into worker bees.

• Workers: In contrast to the queen, workers have small, non-mating ovaries. However, under specific conditions where the queen is lost or her laying ability fails, workers can lay unfertilized eggs that develop into drones. Workers cannot produce fertilized eggs, and their egg-laying typically occurs in response to the absence of the queen's pheromone in the hive (Winston, 1991).

• Drones: Drones are born from unfertilized eggs, and their reproductive system is much simpler than that of queens. They have only one role: mating with the queen. Drones possess a specialized reproductive organ called the endophallus, which is used during mating flights with the queen. After mating, the endophallus remains in the queen's body, and the drone dies.

The honeybee sting is perhaps its most famous anatomical feature. The worker bee's sting has barbs that penetrate the flesh of a vertebrate attacker and remain lodged in it, along with a venom gland and the necessary mechanism for injecting venom into the attacker's body. Interestingly, the sting does not get stuck when attacking other insects (such as other honeybees) because the barbs are not designed for that purpose. The barbs of the sting have evolved to inject the maximum amount of venom when stinging vertebrates.

In general anatomical terms, the sting is connected to a venom sac, which is also connected to the venom gland. The "Kashunikov gland," which produces alarm pheromones, is also located near the sting. Only female bees have stings because their stings are a modified ovipositor. Queen bees have different stings, which will be examined at the end of this section.

The composition of bee venom has long been known. Bee venom is a complex mixture of compounds that causes pain, swelling, and itching. For example, melittin is a small peptide that disrupts cell membranes and constitutes nearly half of the venom's composition. Phospholipase A is also an enzyme that, along with melittin, breaks down cell membranes.

Interestingly, male bees do not have stings, while queens do, but they use their stings only to fight rival queens. The queen's sting is not barbed; therefore, she survives after stinging.

This complex combination of biological and physiological systems makes the honeybee abdomen one of its most important body parts. These structures work harmoniously to enable the bee to perform its tasks within the colony effectively and contribute to the colony's survival.